[PATCH v2 00/37] hrtimer: Provide softirq context hrtimers

[PATCH v2 00/37] hrtimer: Provide softirq context hrtimers

[Anna-Maria Gleixner]

There are quite some places in the kernel which use a combination of
hrtimers and tasklets to make use of the precise expiry of hrtimers, which
schedule a tasklet to bring the actual function into softirq context.

This was introduced when the previous hrtimer softirq code was
removed. That code was implemented by expiring the timer in hard irq
context and then deferring the execution of the callback into softirq
context. That caused a lot of pointless shuffling between the rbtree and a
linked list.

In recent discussions it turned out that more potential users of hrtimers
in softirq context might come up. Aside of that the RT patches need this
functionality as well to defer hrtimers into softirq context if their
callbacks are not interrupt safe on RT.

This series implements a new approach by adding SOFT hrtimer mode and
instead of doing the list shuffle, timers started with this mode are put
into separate soft expiry hrtimer queues. These queues are evaluated only
when the hardirq context detects that the first expiring timer in the
softirq queues has expired. That makes the overhead in the hardirq context
minimal.

The series reworks the code to reuse as much as possible from the existing
facilities for the new softirq hrtimers and integrates them with all
flavours of hrtimers (HIGH_RES=y/n - NOHZ=y/n).

To achieve this quite some of the conditionals in the existing code are
removed for the price of adding some pointless data and state tracking to
the HIGH_RES=n case. That's minimal, but well worth it as it increases the
readability and maintainability of the code.

The first part of the series implements the new functionality and the
second part converts the hrtimer/tasklet users to make use of it and
removes struct hrtimer_tasklet and the surrounding helper functions.

This series is available from git as well:

	git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.timers

Thanks,

        Anna-Maria

---
v1..v2:

  - integration of Peter Zijlstras patch:
    https://lkml.kernel.org/r/20170927164025.GI17526@worktop.programming.kicks-ass.net
  - using hrtimer_mode instead of additional hrtimer clock bases
  - folding the fix for updating the base offsets:
    https://lkml.kernel.org/r/20171006102820.ou4wpm56ed6m3ewr@linutronix.de
  - rework of 08/25 - 10/25 (all of those patches are facing reduction of
    conditional code) and make hrtimer_force_reprogram() unconditional as well
  - integration of new versions of "ALSA/dummy: Replace tasklet with
    softirq hrtimer" and "net/cdc_ncm: Replace tasklet with softirq
    hrtimer"
  - additional hrtimer/tasklet user conversion: "net/mvpp2: Replace tasklet
    with softirq hrtimer"
  - additional fixes of several wrong comments
  - update hrtimer tracing (mode and clock bases)


 drivers/net/ethernet/marvell/mvpp2.c  |   62 +--
 drivers/net/usb/cdc_ncm.c             |   38 --
 drivers/net/wireless/mac80211_hwsim.c |   44 +-
 drivers/usb/gadget/function/f_ncm.c   |   30 -
 include/linux/hrtimer.h               |  110 +++---
 include/linux/interrupt.h             |   25 -
 include/linux/usb/cdc_ncm.h           |    1 
 include/net/xfrm.h                    |    2 
 include/trace/events/timer.h          |   37 +-
 kernel/softirq.c                      |   51 --
 kernel/time/hrtimer.c                 |  623 +++++++++++++++++++++-------------
 kernel/time/timer.c                   |    6 
 net/can/bcm.c                         |  156 ++------
 net/xfrm/xfrm_state.c                 |   30 -
 sound/drivers/dummy.c                 |   27 -
 15 files changed, 652 insertions(+), 590 deletions(-)

[PATCH v2 01/37] hrtimer: Correct blantanly wrong comment

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Correct_blantanly_wrong_comment.patch --]
[-- Type: text/plain, Size: 1297 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

The protection of a hrtimer which runs its callback against migration to a
different CPU has nothing to do with hard interrupt context.

The protection against migration of a hrtimer running the expiry callback
is the pointer in the cpu_base which holds a pointer to the currently
running timer. This pointer is evaluated in the code which potentially
switches the timer base and makes sure it's kept on the CPU on which the
callback is running.

Reported-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1204,9 +1204,9 @@ static void __run_hrtimer(struct hrtimer
 		timer->is_rel = false;
 
 	/*
-	 * Because we run timers from hardirq context, there is no chance
-	 * they get migrated to another cpu, therefore its safe to unlock
-	 * the timer base.
+	 * The timer is marked as running in the cpu base, so it is
+	 * protected against migration to a different CPU even if the lock
+	 * is dropped.
 	 */
 	raw_spin_unlock(&cpu_base->lock);
 	trace_hrtimer_expire_entry(timer, now);

[PATCH v2 02/37] hrtimer: Fix kerneldoc for struct hrtimer_cpu_base

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Fix_kerneldoc_for_struct_hrtimer_cpu_base.patch --]
[-- Type: text/plain, Size: 1617 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

The sequence '/**' marks the start of a struct description. Add the
missing second asterisk. While at it adapt the ordering of the struct
members to the struct definition and document the purpose of
expires_next more precisely.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -144,7 +144,7 @@ enum  hrtimer_base_type {
 	HRTIMER_MAX_CLOCK_BASES,
 };
 
-/*
+/**
  * struct hrtimer_cpu_base - the per cpu clock bases
  * @lock:		lock protecting the base and associated clock bases
  *			and timers
@@ -155,12 +155,12 @@ enum  hrtimer_base_type {
  * @clock_was_set_seq:	Sequence counter of clock was set events
  * @migration_enabled:	The migration of hrtimers to other cpus is enabled
  * @nohz_active:	The nohz functionality is enabled
- * @expires_next:	absolute time of the next event which was scheduled
- *			via clock_set_next_event()
- * @next_timer:		Pointer to the first expiring timer
  * @in_hrtirq:		hrtimer_interrupt() is currently executing
  * @hres_active:	State of high resolution mode
  * @hang_detected:	The last hrtimer interrupt detected a hang
+ * @expires_next:	absolute time of the next event, is required for remote
+ *			hrtimer enqueue
+ * @next_timer:		Pointer to the first expiring timer
  * @nr_events:		Total number of hrtimer interrupt events
  * @nr_retries:		Total number of hrtimer interrupt retries
  * @nr_hangs:		Total number of hrtimer interrupt hangs

[PATCH v2 03/37] hrtimer: Cleanup clock argument in schedule_hrtimeout_range_clock()

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Cleanup_clock_argument_in_schedule_hrtimeout_range_clock.patch --]
[-- Type: text/plain, Size: 2902 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

schedule_hrtimeout_range_clock() uses an integer for the clock id
instead of the predefined type "clockid_t". The ID of the clock is
indicated in hrtimer code as clock_id. Therefore change the name of
the variable as well to make it consistent.

While at it, clean up the description for the function parameters clock_id
and mode. The clock modes and the clock ids are not restricted as the
comment suggests. Fix the mode description as well for the callers of
schedule_hrtimeout_range_clock().

No functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |    2 +-
 kernel/time/hrtimer.c   |   12 ++++++------
 2 files changed, 7 insertions(+), 7 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -466,7 +466,7 @@ extern int schedule_hrtimeout_range(ktim
 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 					  u64 delta,
 					  const enum hrtimer_mode mode,
-					  int clock);
+					  clockid_t clock_id);
 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 
 /* Soft interrupt function to run the hrtimer queues: */
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1671,12 +1671,12 @@ void __init hrtimers_init(void)
  * schedule_hrtimeout_range_clock - sleep until timeout
  * @expires:	timeout value (ktime_t)
  * @delta:	slack in expires timeout (ktime_t)
- * @mode:	timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
- * @clock:	timer clock, CLOCK_MONOTONIC or CLOCK_REALTIME
+ * @mode:	timer mode
+ * @clock_id:	timer clock to be used
  */
 int __sched
 schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
-			       const enum hrtimer_mode mode, int clock)
+			       const enum hrtimer_mode mode, clockid_t clock_id)
 {
 	struct hrtimer_sleeper t;
 
@@ -1697,7 +1697,7 @@ schedule_hrtimeout_range_clock(ktime_t *
 		return -EINTR;
 	}
 
-	hrtimer_init_on_stack(&t.timer, clock, mode);
+	hrtimer_init_on_stack(&t.timer, clock_id, mode);
 	hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
 
 	hrtimer_init_sleeper(&t, current);
@@ -1719,7 +1719,7 @@ schedule_hrtimeout_range_clock(ktime_t *
  * schedule_hrtimeout_range - sleep until timeout
  * @expires:	timeout value (ktime_t)
  * @delta:	slack in expires timeout (ktime_t)
- * @mode:	timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
+ * @mode:	timer mode
  *
  * Make the current task sleep until the given expiry time has
  * elapsed. The routine will return immediately unless
@@ -1758,7 +1758,7 @@ EXPORT_SYMBOL_GPL(schedule_hrtimeout_ran
 /**
  * schedule_hrtimeout - sleep until timeout
  * @expires:	timeout value (ktime_t)
- * @mode:	timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
+ * @mode:	timer mode
  *
  * Make the current task sleep until the given expiry time has
  * elapsed. The routine will return immediately unless

[PATCH v2 04/37] hrtimer: Fix hrtimer function description

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Update-hrtimer_start---function-description.patch --]
[-- Type: text/plain, Size: 2174 bytes --]

The hrtimer_start[_range_ns]() starts a timer reliable on this CPU only
when HRTIMER_MODE_PINNED is set. Furthermore the HRTIMER_MODE_PINNED mode
is not considered, when a hrtimer is initialized.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |    6 +++---
 kernel/time/hrtimer.c   |    9 +++++----
 2 files changed, 8 insertions(+), 7 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -365,11 +365,11 @@ extern void hrtimer_start_range_ns(struc
 				   u64 range_ns, const enum hrtimer_mode mode);
 
 /**
- * hrtimer_start - (re)start an hrtimer on the current CPU
+ * hrtimer_start - (re)start an hrtimer
  * @timer:	the timer to be added
  * @tim:	expiry time
- * @mode:	expiry mode: absolute (HRTIMER_MODE_ABS) or
- *		relative (HRTIMER_MODE_REL)
+ * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
+ *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED)
  */
 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
 				 const enum hrtimer_mode mode)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -933,12 +933,12 @@ static inline ktime_t hrtimer_update_low
 }
 
 /**
- * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
+ * hrtimer_start_range_ns - (re)start an hrtimer
  * @timer:	the timer to be added
  * @tim:	expiry time
  * @delta_ns:	"slack" range for the timer
- * @mode:	expiry mode: absolute (HRTIMER_MODE_ABS) or
- *		relative (HRTIMER_MODE_REL)
+ * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
+ *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED)
  */
 void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 			    u64 delta_ns, const enum hrtimer_mode mode)
@@ -1116,7 +1116,8 @@ static void __hrtimer_init(struct hrtime
  * hrtimer_init - initialize a timer to the given clock
  * @timer:	the timer to be initialized
  * @clock_id:	the clock to be used
- * @mode:	timer mode abs/rel
+ * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
+ *		relative (HRTIMER_MODE_REL); pinned is not considered here!
  */
 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 		  enum hrtimer_mode mode)

[PATCH v2 05/37] hrtimer: Ensure POSIX compliance (relative CLOCK_REALTIME hrtimers)

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Fix-Posix-compliance--relative-CLOCK_REALTIME-hrtimers-.patch --]
[-- Type: text/plain, Size: 1298 bytes --]

POSIX specification defines, that relative CLOCK_REALTIME timers are not
affected by clock modifications. Those timers have to use CLOCK_MONOTONIC
to ensure POSIX compliance.

The introduction of the additional mode HRTIMER_MODE_PINNED broke this
requirement for pinned timers. There is no user space visible impact
because user space timers are not using the pinned mode, but for
consistency reasons this needs to be fixed.

Check whether the mode has the HRTIMER_MODE_REL bit set instead of
comparing with HRTIMER_MODE_ABS.

Fixes: 597d0275736d ("timers: Framework for identifying pinned timers")

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1104,7 +1104,12 @@ static void __hrtimer_init(struct hrtime
 
 	cpu_base = raw_cpu_ptr(&hrtimer_bases);
 
-	if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)
+	/*
+	 * Posix magic: Relative CLOCK_REALTIME timers are not affected by
+	 * clock modifications, so they needs to become CLOCK_MONOTONIC to
+	 * ensure Posix compliance.
+	 */
+	if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
 		clock_id = CLOCK_MONOTONIC;
 
 	base = hrtimer_clockid_to_base(clock_id);

[PATCH v2 06/37] hrtimer: Cleanup hrtimer_mode enum

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Cleanup-hrtimer_mode.patch --]
[-- Type: text/plain, Size: 1295 bytes --]

It's not obvious that the HRTIMER_MODE variants are bit combinations
because all modes are hard coded constants.

Change it so the bit meanings are clear and use the symbols for creating
modes which combine bits.

While at it get rid of the ugly tail comments.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |   16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -28,13 +28,19 @@ struct hrtimer_cpu_base;
 
 /*
  * Mode arguments of xxx_hrtimer functions:
+ *
+ * HRTIMER_MODE_ABS		- Time value is absolute
+ * HRTIMER_MODE_REL		- Time value is relative to now
+ * HRTIMER_MODE_PINNED		- Timer is bound to CPU (is only considered
+ *				  when starting the timer)
  */
 enum hrtimer_mode {
-	HRTIMER_MODE_ABS = 0x0,		/* Time value is absolute */
-	HRTIMER_MODE_REL = 0x1,		/* Time value is relative to now */
-	HRTIMER_MODE_PINNED = 0x02,	/* Timer is bound to CPU */
-	HRTIMER_MODE_ABS_PINNED = 0x02,
-	HRTIMER_MODE_REL_PINNED = 0x03,
+	HRTIMER_MODE_ABS	= 0x00,
+	HRTIMER_MODE_REL	= 0x01,
+	HRTIMER_MODE_PINNED	= 0x02,
+
+	HRTIMER_MODE_ABS_PINNED = HRTIMER_MODE_ABS | HRTIMER_MODE_PINNED,
+	HRTIMER_MODE_REL_PINNED = HRTIMER_MODE_REL | HRTIMER_MODE_PINNED,
 };
 
 /*

[PATCH v2 07/37] tracing: hrtimer: Take all clock bases and modes into account

[Anna-Maria Gleixner]

[-- Attachment #1: tracing--hrtimer--Take-all-bases-and-modes-into-account.patch --]
[-- Type: text/plain, Size: 1643 bytes --]

So far only CLOCK_MONOTONIC and CLOCK_REALTIME were taken into account as
well as HRTIMER_MODE_ABS/REL in hrtimer_init tracepoint. The query for
detecting timer mode ABS or REL is not valid, since the introduction of
HRTIMER_MODE_PINNED.

HRTIMER_MODE_PINNED is not evaluated in hrtimer_init() call. But for the
sake of completeness print all given modes.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/trace/events/timer.h |   20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -135,6 +135,20 @@ DEFINE_EVENT(timer_class, timer_cancel,
 	TP_ARGS(timer)
 );
 
+#define decode_clockid(type)						\
+	__print_symbolic(type,						\
+		{ CLOCK_REALTIME,	"CLOCK_REALTIME"	},	\
+		{ CLOCK_MONOTONIC,	"CLOCK_MONOTONIC"	},	\
+		{ CLOCK_BOOTTIME,	"CLOCK_BOOTTIME"	},	\
+		{ CLOCK_TAI,		"CLOCK_TAI"		})
+
+#define decode_hrtimer_mode(mode)					\
+	__print_symbolic(mode,						\
+		{ HRTIMER_MODE_ABS,		"ABS"		},	\
+		{ HRTIMER_MODE_REL,		"REL"		},	\
+		{ HRTIMER_MODE_ABS_PINNED,	"ABS|PINNED"	},	\
+		{ HRTIMER_MODE_REL_PINNED,	"REL|PINNED"	})
+
 /**
  * hrtimer_init - called when the hrtimer is initialized
  * @hrtimer:	pointer to struct hrtimer
@@ -161,10 +175,8 @@ TRACE_EVENT(hrtimer_init,
 	),
 
 	TP_printk("hrtimer=%p clockid=%s mode=%s", __entry->hrtimer,
-		  __entry->clockid == CLOCK_REALTIME ?
-			"CLOCK_REALTIME" : "CLOCK_MONOTONIC",
-		  __entry->mode == HRTIMER_MODE_ABS ?
-			"HRTIMER_MODE_ABS" : "HRTIMER_MODE_REL")
+		  decode_clockid(__entry->clockid),
+		  decode_hrtimer_mode(__entry->mode))
 );
 
 /**

[PATCH v2 08/37] tracing: hrtimer: Print hrtimer mode in hrtimer_start tracepoint

[Anna-Maria Gleixner]

[-- Attachment #1: tracing--hrtimer--Print-hrtimer-mode-in-hrtimer_start-tracepoint.patch --]
[-- Type: text/plain, Size: 3350 bytes --]

The hrtimer_start tracepoint lacks the mode information. The mode is
important because consecutive starts can switch from ABS to REL or from
PINNED to non PINNED.

Add the mode information.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/trace/events/timer.h |   13 ++++++++-----
 kernel/time/hrtimer.c        |   16 +++++++++-------
 2 files changed, 17 insertions(+), 12 deletions(-)

--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -185,15 +185,16 @@ TRACE_EVENT(hrtimer_init,
  */
 TRACE_EVENT(hrtimer_start,
 
-	TP_PROTO(struct hrtimer *hrtimer),
+	TP_PROTO(struct hrtimer *hrtimer, enum hrtimer_mode mode),
 
-	TP_ARGS(hrtimer),
+	TP_ARGS(hrtimer, mode),
 
 	TP_STRUCT__entry(
 		__field( void *,	hrtimer		)
 		__field( void *,	function	)
 		__field( s64,		expires		)
 		__field( s64,		softexpires	)
+		__field( enum hrtimer_mode,	mode	)
 	),
 
 	TP_fast_assign(
@@ -201,12 +202,14 @@ TRACE_EVENT(hrtimer_start,
 		__entry->function	= hrtimer->function;
 		__entry->expires	= hrtimer_get_expires(hrtimer);
 		__entry->softexpires	= hrtimer_get_softexpires(hrtimer);
+		__entry->mode		= mode;
 	),
 
-	TP_printk("hrtimer=%p function=%pf expires=%llu softexpires=%llu",
-		  __entry->hrtimer, __entry->function,
+	TP_printk("hrtimer=%p function=%pf expires=%llu softexpires=%llu "
+		  "mode=%s", __entry->hrtimer, __entry->function,
 		  (unsigned long long) __entry->expires,
-		  (unsigned long long) __entry->softexpires)
+		  (unsigned long long) __entry->softexpires,
+		  decode_hrtimer_mode(__entry->mode))
 );
 
 /**
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -442,10 +442,11 @@ debug_init(struct hrtimer *timer, clocki
 	trace_hrtimer_init(timer, clockid, mode);
 }
 
-static inline void debug_activate(struct hrtimer *timer)
+static inline void debug_activate(struct hrtimer *timer,
+				  enum hrtimer_mode mode)
 {
 	debug_hrtimer_activate(timer);
-	trace_hrtimer_start(timer);
+	trace_hrtimer_start(timer, mode);
 }
 
 static inline void debug_deactivate(struct hrtimer *timer)
@@ -837,9 +838,10 @@ EXPORT_SYMBOL_GPL(hrtimer_forward);
  * Returns 1 when the new timer is the leftmost timer in the tree.
  */
 static int enqueue_hrtimer(struct hrtimer *timer,
-			   struct hrtimer_clock_base *base)
+			   struct hrtimer_clock_base *base,
+			   enum hrtimer_mode mode)
 {
-	debug_activate(timer);
+	debug_activate(timer, mode);
 
 	base->cpu_base->active_bases |= 1 << base->index;
 
@@ -962,7 +964,7 @@ void hrtimer_start_range_ns(struct hrtim
 	/* Switch the timer base, if necessary: */
 	new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
 
-	leftmost = enqueue_hrtimer(timer, new_base);
+	leftmost = enqueue_hrtimer(timer, new_base, mode);
 	if (!leftmost)
 		goto unlock;
 
@@ -1231,7 +1233,7 @@ static void __run_hrtimer(struct hrtimer
 	 */
 	if (restart != HRTIMER_NORESTART &&
 	    !(timer->state & HRTIMER_STATE_ENQUEUED))
-		enqueue_hrtimer(timer, base);
+		enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
 
 	/*
 	 * Separate the ->running assignment from the ->state assignment.
@@ -1630,7 +1632,7 @@ static void migrate_hrtimer_list(struct
 		 * sort out already expired timers and reprogram the
 		 * event device.
 		 */
-		enqueue_hrtimer(timer, new_base);
+		enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
 	}
 }
 

[PATCH v2 09/37] hrtimer: Switch for loop to _ffs() evaluation

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Switch_for_loop_to__ffs_evaluation.patch --]
[-- Type: text/plain, Size: 2340 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

Looping over all clock bases to find active bits is suboptimal if not all
bases are active.

Avoid this by converting it to a __ffs() evaluation. The functionallity is
outsourced into an own function and is called via a macro as suggested by
Peter Zijlstra. 

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |   31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -464,20 +464,34 @@ static inline void hrtimer_update_next_t
 #endif
 }
 
+static struct hrtimer_clock_base *
+__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
+{
+	struct hrtimer_clock_base *base = NULL;
+
+	if (*active) {
+		unsigned int idx = __ffs(*active);
+		*active &= ~(1U << idx);
+		base = &cpu_base->clock_base[idx];
+	}
+
+	return base;
+}
+
+#define for_each_active_base(base, cpu_base, active)	\
+	while ((base = __next_base((cpu_base), &(active))))
+
 static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
 {
-	struct hrtimer_clock_base *base = cpu_base->clock_base;
+	struct hrtimer_clock_base *base;
 	unsigned int active = cpu_base->active_bases;
 	ktime_t expires, expires_next = KTIME_MAX;
 
 	hrtimer_update_next_timer(cpu_base, NULL);
-	for (; active; base++, active >>= 1) {
+	for_each_active_base(base, cpu_base, active) {
 		struct timerqueue_node *next;
 		struct hrtimer *timer;
 
-		if (!(active & 0x01))
-			continue;
-
 		next = timerqueue_getnext(&base->active);
 		timer = container_of(next, struct hrtimer, node);
 		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
@@ -1250,16 +1264,13 @@ static void __run_hrtimer(struct hrtimer
 
 static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
 {
-	struct hrtimer_clock_base *base = cpu_base->clock_base;
+	struct hrtimer_clock_base *base;
 	unsigned int active = cpu_base->active_bases;
 
-	for (; active; base++, active >>= 1) {
+	for_each_active_base(base, cpu_base, active) {
 		struct timerqueue_node *node;
 		ktime_t basenow;
 
-		if (!(active & 0x01))
-			continue;
-
 		basenow = ktime_add(now, base->offset);
 
 		while ((node = timerqueue_getnext(&base->active))) {

[PATCH v2 10/37] hrtimer: Store running timer in hrtimer_clock_base

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Store_running_timer_in_hrtimer_clock_base.patch --]
[-- Type: text/plain, Size: 6474 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

The pointer to the currently running timer is stored in hrtimer_cpu_base
before the base lock is dropped and the callback is invoked.

This results in two levels of indirections and the upcoming support for
softirq based hrtimer requires splitting the "running" storage into soft
and hard irq context expiry.

Storing both in the cpu base would require conditionals in all code paths
accessing that information.

It's possible to have a per clock base sequence count and running pointer
without changing the semantics of the related mechanisms because the timer
base pointer cannot be changed while a timer is running the callback.

Unfortunately this makes cpu_clock base larger than 32 bytes on 32bit
kernels. Instead of having huge gaps due to alignment, remove the alignment
and let the compiler pack cpu base for 32bit. The resulting cache access
patterns are fortunately not really different from the current
behaviour. On 64bit kernels the 64byte alignment stays and the behaviour is
unchanged. This was determined by analyzing the resulting layout and
looking at the number of cache lines involved for the frequently used
clocks.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |   20 +++++++++-----------
 kernel/time/hrtimer.c   |   28 +++++++++++++---------------
 2 files changed, 22 insertions(+), 26 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -118,9 +118,9 @@ struct hrtimer_sleeper {
 };
 
 #ifdef CONFIG_64BIT
-# define HRTIMER_CLOCK_BASE_ALIGN	64
+# define __hrtimer_clock_base_align	____cacheline_aligned
 #else
-# define HRTIMER_CLOCK_BASE_ALIGN	32
+# define __hrtimer_clock_base_align
 #endif
 
 /**
@@ -129,18 +129,22 @@ struct hrtimer_sleeper {
  * @index:		clock type index for per_cpu support when moving a
  *			timer to a base on another cpu.
  * @clockid:		clock id for per_cpu support
+ * @seq:		seqcount around __run_hrtimer
+ * @running:		pointer to the currently running hrtimer
  * @active:		red black tree root node for the active timers
  * @get_time:		function to retrieve the current time of the clock
  * @offset:		offset of this clock to the monotonic base
  */
 struct hrtimer_clock_base {
 	struct hrtimer_cpu_base	*cpu_base;
-	int			index;
+	unsigned int		index;
 	clockid_t		clockid;
+	seqcount_t		seq;
+	struct hrtimer		*running;
 	struct timerqueue_head	active;
 	ktime_t			(*get_time)(void);
 	ktime_t			offset;
-} __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
+} __hrtimer_clock_base_align;
 
 enum  hrtimer_base_type {
 	HRTIMER_BASE_MONOTONIC,
@@ -154,8 +158,6 @@ enum  hrtimer_base_type {
  * struct hrtimer_cpu_base - the per cpu clock bases
  * @lock:		lock protecting the base and associated clock bases
  *			and timers
- * @seq:		seqcount around __run_hrtimer
- * @running:		pointer to the currently running hrtimer
  * @cpu:		cpu number
  * @active_bases:	Bitfield to mark bases with active timers
  * @clock_was_set_seq:	Sequence counter of clock was set events
@@ -179,8 +181,6 @@ enum  hrtimer_base_type {
  */
 struct hrtimer_cpu_base {
 	raw_spinlock_t			lock;
-	seqcount_t			seq;
-	struct hrtimer			*running;
 	unsigned int			cpu;
 	unsigned int			active_bases;
 	unsigned int			clock_was_set_seq;
@@ -202,8 +202,6 @@ struct hrtimer_cpu_base {
 
 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 {
-	BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
-
 	timer->node.expires = time;
 	timer->_softexpires = time;
 }
@@ -428,7 +426,7 @@ static inline int hrtimer_is_queued(stru
  */
 static inline int hrtimer_callback_running(struct hrtimer *timer)
 {
-	return timer->base->cpu_base->running == timer;
+	return timer->base->running == timer;
 }
 
 /* Forward a hrtimer so it expires after now: */
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -70,7 +70,6 @@
 DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
 {
 	.lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
-	.seq = SEQCNT_ZERO(hrtimer_bases.seq),
 	.clock_base =
 	{
 		{
@@ -118,7 +117,6 @@ static const int hrtimer_clock_to_base_t
  * timer->base->cpu_base
  */
 static struct hrtimer_cpu_base migration_cpu_base = {
-	.seq = SEQCNT_ZERO(migration_cpu_base),
 	.clock_base = { { .cpu_base = &migration_cpu_base, }, },
 };
 
@@ -1157,19 +1155,19 @@ EXPORT_SYMBOL_GPL(hrtimer_init);
  */
 bool hrtimer_active(const struct hrtimer *timer)
 {
-	struct hrtimer_cpu_base *cpu_base;
+	struct hrtimer_clock_base *base;
 	unsigned int seq;
 
 	do {
-		cpu_base = READ_ONCE(timer->base->cpu_base);
-		seq = raw_read_seqcount_begin(&cpu_base->seq);
+		base = READ_ONCE(timer->base);
+		seq = raw_read_seqcount_begin(&base->seq);
 
 		if (timer->state != HRTIMER_STATE_INACTIVE ||
-		    cpu_base->running == timer)
+		    base->running == timer)
 			return true;
 
-	} while (read_seqcount_retry(&cpu_base->seq, seq) ||
-		 cpu_base != READ_ONCE(timer->base->cpu_base));
+	} while (read_seqcount_retry(&base->seq, seq) ||
+		 base != READ_ONCE(timer->base));
 
 	return false;
 }
@@ -1203,16 +1201,16 @@ static void __run_hrtimer(struct hrtimer
 	lockdep_assert_held(&cpu_base->lock);
 
 	debug_deactivate(timer);
-	cpu_base->running = timer;
+	base->running = timer;
 
 	/*
 	 * Separate the ->running assignment from the ->state assignment.
 	 *
 	 * As with a regular write barrier, this ensures the read side in
-	 * hrtimer_active() cannot observe cpu_base->running == NULL &&
+	 * hrtimer_active() cannot observe base->running == NULL &&
 	 * timer->state == INACTIVE.
 	 */
-	raw_write_seqcount_barrier(&cpu_base->seq);
+	raw_write_seqcount_barrier(&base->seq);
 
 	__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
 	fn = timer->function;
@@ -1253,13 +1251,13 @@ static void __run_hrtimer(struct hrtimer
 	 * Separate the ->running assignment from the ->state assignment.
 	 *
 	 * As with a regular write barrier, this ensures the read side in
-	 * hrtimer_active() cannot observe cpu_base->running == NULL &&
+	 * hrtimer_active() cannot observe base->running.timer == NULL &&
 	 * timer->state == INACTIVE.
 	 */
-	raw_write_seqcount_barrier(&cpu_base->seq);
+	raw_write_seqcount_barrier(&base->seq);
 
-	WARN_ON_ONCE(cpu_base->running != timer);
-	cpu_base->running = NULL;
+	WARN_ON_ONCE(base->running != timer);
+	base->running = NULL;
 }
 
 static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)

[PATCH v2 11/37] hrtimer: Change boolean struct members into bitfield

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Change-bool-into-bitfield.patch --]
[-- Type: text/plain, Size: 1908 bytes --]

The struct member migration_enabled and nohz_active of struct
hrtimer_cpu_base are boolean. Thus, they cannot easily be packed with the
subsequent bitfield when CONFIG_HIGH_RES_TIMERS is enabled.

Change the type of boolean struct members into bitfield. Adapt the function
timers_update_migration() which updates those members.

No functional change.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |    4 ++--
 kernel/time/timer.c     |    6 ++++--
 2 files changed, 6 insertions(+), 4 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -184,8 +184,8 @@ struct hrtimer_cpu_base {
 	unsigned int			cpu;
 	unsigned int			active_bases;
 	unsigned int			clock_was_set_seq;
-	bool				migration_enabled;
-	bool				nohz_active;
+	unsigned int			migration_enabled	: 1,
+					nohz_active		: 1;
 #ifdef CONFIG_HIGH_RES_TIMERS
 	unsigned int			in_hrtirq	: 1,
 					hres_active	: 1,
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -216,6 +216,7 @@ unsigned int sysctl_timer_migration = 1;
 void timers_update_migration(bool update_nohz)
 {
 	bool on = sysctl_timer_migration && tick_nohz_active;
+	struct hrtimer_cpu_base *base;
 	unsigned int cpu;
 
 	/* Avoid the loop, if nothing to update */
@@ -225,12 +226,13 @@ void timers_update_migration(bool update
 	for_each_possible_cpu(cpu) {
 		per_cpu(timer_bases[BASE_STD].migration_enabled, cpu) = on;
 		per_cpu(timer_bases[BASE_DEF].migration_enabled, cpu) = on;
-		per_cpu(hrtimer_bases.migration_enabled, cpu) = on;
+		base = per_cpu_ptr(&hrtimer_bases, cpu);
+		base->migration_enabled = on;
 		if (!update_nohz)
 			continue;
 		per_cpu(timer_bases[BASE_STD].nohz_active, cpu) = true;
 		per_cpu(timer_bases[BASE_DEF].nohz_active, cpu) = true;
-		per_cpu(hrtimer_bases.nohz_active, cpu) = true;
+		base->nohz_active = true;
 	}
 }
 

[PATCH v2 12/37] hrtimer: Make room in struct hrtimer_cpu_base

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Change-unsigend-int-to-short.patch --]
[-- Type: text/plain, Size: 963 bytes --]

The upcoming softirq based hrtimers support requires an additional field in
the hrtimer_cpu_base struct, which would grow the struct size beyond a
cache line.

The struct members nr_retries and nr_hangs of hrtimer_cpu_base are solely
used for diagnostic output and have no requirement to be unsigned int.

Make them unsigned short to create room for the new struct member. No
functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -193,8 +193,8 @@ struct hrtimer_cpu_base {
 	ktime_t				expires_next;
 	struct hrtimer			*next_timer;
 	unsigned int			nr_events;
-	unsigned int			nr_retries;
-	unsigned int			nr_hangs;
+	unsigned short			nr_retries;
+	unsigned short			nr_hangs;
 	unsigned int			max_hang_time;
 #endif
 	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];

[PATCH v2 13/37] hrtimer: Reduce conditional code (hres_active)

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--make-hrtimer_hres_active---available-in-all-cases.patch --]
[-- Type: text/plain, Size: 3889 bytes --]

The hrtimer_cpu_base struct has the CONFIG_HIGH_RES_TIMERS conditional
struct member hres_active. All related functions to this member are
conditional as well.

There is no functional change, when the hres_active member is
unconditional with all related functions and is set to zero during
initialization.

The conditional code sections can be avoided by adding IS_ENABLED(HIGHRES)
conditionals into common functions, which ensures dead code elimination.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |   20 ++++++++------------
 kernel/time/hrtimer.c   |   31 +++++++++++++++----------------
 2 files changed, 23 insertions(+), 28 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -185,10 +185,10 @@ struct hrtimer_cpu_base {
 	unsigned int			active_bases;
 	unsigned int			clock_was_set_seq;
 	unsigned int			migration_enabled	: 1,
-					nohz_active		: 1;
+					nohz_active		: 1,
+					hres_active		: 1;
 #ifdef CONFIG_HIGH_RES_TIMERS
 	unsigned int			in_hrtirq	: 1,
-					hres_active	: 1,
 					hang_detected	: 1;
 	ktime_t				expires_next;
 	struct hrtimer			*next_timer;
@@ -270,16 +270,17 @@ static inline ktime_t hrtimer_cb_get_tim
 	return timer->base->get_time();
 }
 
+static inline int hrtimer_is_hres_active(struct hrtimer *timer)
+{
+	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
+		timer->base->cpu_base->hres_active : 0;
+}
+
 #ifdef CONFIG_HIGH_RES_TIMERS
 struct clock_event_device;
 
 extern void hrtimer_interrupt(struct clock_event_device *dev);
 
-static inline int hrtimer_is_hres_active(struct hrtimer *timer)
-{
-	return timer->base->cpu_base->hres_active;
-}
-
 /*
  * The resolution of the clocks. The resolution value is returned in
  * the clock_getres() system call to give application programmers an
@@ -302,11 +303,6 @@ extern unsigned int hrtimer_resolution;
 
 #define hrtimer_resolution	(unsigned int)LOW_RES_NSEC
 
-static inline int hrtimer_is_hres_active(struct hrtimer *timer)
-{
-	return 0;
-}
-
 static inline void clock_was_set_delayed(void) { }
 
 #endif
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -519,6 +519,20 @@ static inline ktime_t hrtimer_update_bas
 					    offs_real, offs_boot, offs_tai);
 }
 
+/*
+ * Is the high resolution mode active ?
+ */
+static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
+{
+	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
+		cpu_base->hres_active : 0;
+}
+
+static inline int hrtimer_hres_active(void)
+{
+	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
+}
+
 /* High resolution timer related functions */
 #ifdef CONFIG_HIGH_RES_TIMERS
 
@@ -548,19 +562,6 @@ static inline int hrtimer_is_hres_enable
 }
 
 /*
- * Is the high resolution mode active ?
- */
-static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
-{
-	return cpu_base->hres_active;
-}
-
-static inline int hrtimer_hres_active(void)
-{
-	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
-}
-
-/*
  * Reprogram the event source with checking both queues for the
  * next event
  * Called with interrupts disabled and base->lock held
@@ -668,7 +669,6 @@ static void hrtimer_reprogram(struct hrt
 static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
 {
 	base->expires_next = KTIME_MAX;
-	base->hres_active = 0;
 }
 
 /*
@@ -727,8 +727,6 @@ void clock_was_set_delayed(void)
 
 #else
 
-static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *b) { return 0; }
-static inline int hrtimer_hres_active(void) { return 0; }
 static inline int hrtimer_is_hres_enabled(void) { return 0; }
 static inline void hrtimer_switch_to_hres(void) { }
 static inline void
@@ -1609,6 +1607,7 @@ int hrtimers_prepare_cpu(unsigned int cp
 	}
 
 	cpu_base->cpu = cpu;
+	cpu_base->hres_active = 0;
 	hrtimer_init_hres(cpu_base);
 	return 0;
 }

[PATCH v2 14/37] hrtimer: Use accesor functions instead of direct access

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Use-predefined-hres_active---functions.patch --]
[-- Type: text/plain, Size: 809 bytes --]

__hrtimer_hres_active() is now available unconditionally. Replace the
direct access to hrtimer_cpu_base.hres_active.

No functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -571,7 +571,7 @@ hrtimer_force_reprogram(struct hrtimer_c
 {
 	ktime_t expires_next;
 
-	if (!cpu_base->hres_active)
+	if (!__hrtimer_hres_active(cpu_base))
 		return;
 
 	expires_next = __hrtimer_get_next_event(cpu_base);
@@ -680,7 +680,7 @@ static void retrigger_next_event(void *a
 {
 	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
 
-	if (!base->hres_active)
+	if (!__hrtimer_hres_active(base))
 		return;
 
 	raw_spin_lock(&base->lock);

[PATCH v2 15/37] hrtimer: Make the remote enqueue check unconditional

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--remote-enqueue.patch --]
[-- Type: text/plain, Size: 4371 bytes --]

hrtimer_cpu_base.expires_next is used to cache the next event armed in the
timer hardware. The value is used to check whether an hrtimer can be
enqueued remotely. If the new hrtimer is expiring before expires_next, then
remote enqueue is not possible as the remote hrtimer hardware cannot be
accessed for reprogramming to an earlier expiry time.

The remote enqueue check is currently conditional on
CONFIG_HIGH_RES_TIMERS=y and hrtimer_cpu_base.hres_active. There is no
compelling reason to make this conditional.

Move hrtimer_cpu_base.expires_next out of the CONFIG_HIGH_RES_TIMERS=y
guarded area and remove the conditionals in hrtimer_check_target().

The check is currently a NOOP for the CONFIG_HIGH_RES_TIMERS=n and the
!hrtimer_cpu_base.hres_active case because in these cases nothing updates
hrtimer_cpu_base.expires_next yet. This will be changed with later patches
which further reduce the #ifdef zoo in this code.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |    6 +++---
 kernel/time/hrtimer.c   |   26 ++++++--------------------
 2 files changed, 9 insertions(+), 23 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -166,13 +166,13 @@ enum  hrtimer_base_type {
  * @in_hrtirq:		hrtimer_interrupt() is currently executing
  * @hres_active:	State of high resolution mode
  * @hang_detected:	The last hrtimer interrupt detected a hang
- * @expires_next:	absolute time of the next event, is required for remote
- *			hrtimer enqueue
  * @next_timer:		Pointer to the first expiring timer
  * @nr_events:		Total number of hrtimer interrupt events
  * @nr_retries:		Total number of hrtimer interrupt retries
  * @nr_hangs:		Total number of hrtimer interrupt hangs
  * @max_hang_time:	Maximum time spent in hrtimer_interrupt
+ * @expires_next:	absolute time of the next event, is required for remote
+ *			hrtimer enqueue
  * @clock_base:		array of clock bases for this cpu
  *
  * Note: next_timer is just an optimization for __remove_hrtimer().
@@ -190,13 +190,13 @@ struct hrtimer_cpu_base {
 #ifdef CONFIG_HIGH_RES_TIMERS
 	unsigned int			in_hrtirq	: 1,
 					hang_detected	: 1;
-	ktime_t				expires_next;
 	struct hrtimer			*next_timer;
 	unsigned int			nr_events;
 	unsigned short			nr_retries;
 	unsigned short			nr_hangs;
 	unsigned int			max_hang_time;
 #endif
+	ktime_t				expires_next;
 	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
 } ____cacheline_aligned;
 
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -154,26 +154,21 @@ struct hrtimer_clock_base *lock_hrtimer_
 }
 
 /*
- * With HIGHRES=y we do not migrate the timer when it is expiring
- * before the next event on the target cpu because we cannot reprogram
- * the target cpu hardware and we would cause it to fire late.
+ * We do not migrate the timer when it is expiring before the next
+ * event on the target cpu. When high resolution is enabled, we cannot
+ * reprogram the target cpu hardware and we would cause it to fire
+ * late. To keep it simple, we handle the high resolution enabled and
+ * disabled case similar.
  *
  * Called with cpu_base->lock of target cpu held.
  */
 static int
 hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
 {
-#ifdef CONFIG_HIGH_RES_TIMERS
 	ktime_t expires;
 
-	if (!new_base->cpu_base->hres_active)
-		return 0;
-
 	expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
 	return expires <= new_base->cpu_base->expires_next;
-#else
-	return 0;
-#endif
 }
 
 #ifdef CONFIG_NO_HZ_COMMON
@@ -664,14 +659,6 @@ static void hrtimer_reprogram(struct hrt
 }
 
 /*
- * Initialize the high resolution related parts of cpu_base
- */
-static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
-{
-	base->expires_next = KTIME_MAX;
-}
-
-/*
  * Retrigger next event is called after clock was set
  *
  * Called with interrupts disabled via on_each_cpu()
@@ -736,7 +723,6 @@ static inline int hrtimer_reprogram(stru
 {
 	return 0;
 }
-static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
 static inline void retrigger_next_event(void *arg) { }
 
 #endif /* CONFIG_HIGH_RES_TIMERS */
@@ -1608,7 +1594,7 @@ int hrtimers_prepare_cpu(unsigned int cp
 
 	cpu_base->cpu = cpu;
 	cpu_base->hres_active = 0;
-	hrtimer_init_hres(cpu_base);
+	cpu_base->expires_next = KTIME_MAX;
 	return 0;
 }
 

[PATCH v2 16/37] hrtimer: Make hrtimer_cpu_base.next_timer handling unconditional

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--next_timer.patch --]
[-- Type: text/plain, Size: 3503 bytes --]

hrtimer_cpu_base.next_timer stores the pointer to the next expiring timer
in a cpu base.

This pointer cannot be dereferenced and is solely used to check whether a
hrtimer which is removed is the hrtimer which is the first to expire in the
CPU base. If this is the case, then the timer hardware needs to be
reprogrammed to avoid an extra interrupt for nothing.

Again, this is conditional functionality, but there is no compelling reason
to make this conditional. As a preparation, hrtimer_cpu_base.next_timer
needs to be available unconditonal. Aside of that the upcoming support for
softirq based hrtimers requires access to this pointer unconditionally.

Make the update of hrtimer_cpu_base.next_timer unconditional and remove the
ifdef cruft. The impact on CONFIG_HIGH_RES_TIMERS=n && CONFIG_NOHZ=n is
marginal as it's just a store on an already dirtied cacheline.

No functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |    4 ++--
 kernel/time/hrtimer.c   |   12 ++----------
 2 files changed, 4 insertions(+), 12 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -166,13 +166,13 @@ enum  hrtimer_base_type {
  * @in_hrtirq:		hrtimer_interrupt() is currently executing
  * @hres_active:	State of high resolution mode
  * @hang_detected:	The last hrtimer interrupt detected a hang
- * @next_timer:		Pointer to the first expiring timer
  * @nr_events:		Total number of hrtimer interrupt events
  * @nr_retries:		Total number of hrtimer interrupt retries
  * @nr_hangs:		Total number of hrtimer interrupt hangs
  * @max_hang_time:	Maximum time spent in hrtimer_interrupt
  * @expires_next:	absolute time of the next event, is required for remote
  *			hrtimer enqueue
+ * @next_timer:		Pointer to the first expiring timer
  * @clock_base:		array of clock bases for this cpu
  *
  * Note: next_timer is just an optimization for __remove_hrtimer().
@@ -190,13 +190,13 @@ struct hrtimer_cpu_base {
 #ifdef CONFIG_HIGH_RES_TIMERS
 	unsigned int			in_hrtirq	: 1,
 					hang_detected	: 1;
-	struct hrtimer			*next_timer;
 	unsigned int			nr_events;
 	unsigned short			nr_retries;
 	unsigned short			nr_hangs;
 	unsigned int			max_hang_time;
 #endif
 	ktime_t				expires_next;
+	struct hrtimer			*next_timer;
 	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
 } ____cacheline_aligned;
 
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -449,14 +449,6 @@ static inline void debug_deactivate(stru
 }
 
 #if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
-static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base,
-					     struct hrtimer *timer)
-{
-#ifdef CONFIG_HIGH_RES_TIMERS
-	cpu_base->next_timer = timer;
-#endif
-}
-
 static struct hrtimer_clock_base *
 __next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
 {
@@ -480,7 +472,7 @@ static ktime_t __hrtimer_get_next_event(
 	unsigned int active = cpu_base->active_bases;
 	ktime_t expires, expires_next = KTIME_MAX;
 
-	hrtimer_update_next_timer(cpu_base, NULL);
+	cpu_base->next_timer = NULL;
 	for_each_active_base(base, cpu_base, active) {
 		struct timerqueue_node *next;
 		struct hrtimer *timer;
@@ -490,7 +482,7 @@ static ktime_t __hrtimer_get_next_event(
 		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 		if (expires < expires_next) {
 			expires_next = expires;
-			hrtimer_update_next_timer(cpu_base, timer);
+			cpu_base->next_timer = timer;
 		}
 	}
 	/*

[PATCH v2 17/37] hrtimer: Make hrtimer_reprogramm() unconditional

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--reprogramm--.patch --]
[-- Type: text/plain, Size: 5576 bytes --]

hrtimer_reprogram() needs to be available unconditionally for softirq based
hrtimers. Move the function and all required struct members out of the
CONFIG_HIGH_RES_TIMERS #ifdef.

There is no functional change because hrtimer_reprogram() is only invoked
when hrtimer_cpu_base.hres_active is true. Making it unconditional
increases the text size for the CONFIG_HIGH_RES_TIMERS=n case, but avoids
replication of that code for the upcoming softirq based hrtimers support.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |    6 +-
 kernel/time/hrtimer.c   |  129 +++++++++++++++++++++++-------------------------
 2 files changed, 65 insertions(+), 70 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -186,10 +186,10 @@ struct hrtimer_cpu_base {
 	unsigned int			clock_was_set_seq;
 	unsigned int			migration_enabled	: 1,
 					nohz_active		: 1,
-					hres_active		: 1;
+					in_hrtirq		: 1,
+					hres_active		: 1,
+					hang_detected		: 1;
 #ifdef CONFIG_HIGH_RES_TIMERS
-	unsigned int			in_hrtirq	: 1,
-					hang_detected	: 1;
 	unsigned int			nr_events;
 	unsigned short			nr_retries;
 	unsigned short			nr_hangs;
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -589,68 +589,6 @@ hrtimer_force_reprogram(struct hrtimer_c
 }
 
 /*
- * When a timer is enqueued and expires earlier than the already enqueued
- * timers, we have to check, whether it expires earlier than the timer for
- * which the clock event device was armed.
- *
- * Called with interrupts disabled and base->cpu_base.lock held
- */
-static void hrtimer_reprogram(struct hrtimer *timer,
-			      struct hrtimer_clock_base *base)
-{
-	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
-	ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
-
-	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
-
-	/*
-	 * If the timer is not on the current cpu, we cannot reprogram
-	 * the other cpus clock event device.
-	 */
-	if (base->cpu_base != cpu_base)
-		return;
-
-	/*
-	 * If the hrtimer interrupt is running, then it will
-	 * reevaluate the clock bases and reprogram the clock event
-	 * device. The callbacks are always executed in hard interrupt
-	 * context so we don't need an extra check for a running
-	 * callback.
-	 */
-	if (cpu_base->in_hrtirq)
-		return;
-
-	/*
-	 * CLOCK_REALTIME timer might be requested with an absolute
-	 * expiry time which is less than base->offset. Set it to 0.
-	 */
-	if (expires < 0)
-		expires = 0;
-
-	if (expires >= cpu_base->expires_next)
-		return;
-
-	/* Update the pointer to the next expiring timer */
-	cpu_base->next_timer = timer;
-
-	/*
-	 * If a hang was detected in the last timer interrupt then we
-	 * do not schedule a timer which is earlier than the expiry
-	 * which we enforced in the hang detection. We want the system
-	 * to make progress.
-	 */
-	if (cpu_base->hang_detected)
-		return;
-
-	/*
-	 * Program the timer hardware. We enforce the expiry for
-	 * events which are already in the past.
-	 */
-	cpu_base->expires_next = expires;
-	tick_program_event(expires, 1);
-}
-
-/*
  * Retrigger next event is called after clock was set
  *
  * Called with interrupts disabled via on_each_cpu()
@@ -710,16 +648,73 @@ static inline int hrtimer_is_hres_enable
 static inline void hrtimer_switch_to_hres(void) { }
 static inline void
 hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
-static inline int hrtimer_reprogram(struct hrtimer *timer,
-				    struct hrtimer_clock_base *base)
-{
-	return 0;
-}
 static inline void retrigger_next_event(void *arg) { }
 
 #endif /* CONFIG_HIGH_RES_TIMERS */
 
 /*
+ * When a timer is enqueued and expires earlier than the already enqueued
+ * timers, we have to check, whether it expires earlier than the timer for
+ * which the clock event device was armed.
+ *
+ * Called with interrupts disabled and base->cpu_base.lock held
+ */
+static void hrtimer_reprogram(struct hrtimer *timer,
+			      struct hrtimer_clock_base *base)
+{
+	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+	ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
+
+	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
+
+	/*
+	 * If the timer is not on the current cpu, we cannot reprogram
+	 * the other cpus clock event device.
+	 */
+	if (base->cpu_base != cpu_base)
+		return;
+
+	/*
+	 * If the hrtimer interrupt is running, then it will
+	 * reevaluate the clock bases and reprogram the clock event
+	 * device. The callbacks are always executed in hard interrupt
+	 * context so we don't need an extra check for a running
+	 * callback.
+	 */
+	if (cpu_base->in_hrtirq)
+		return;
+
+	/*
+	 * CLOCK_REALTIME timer might be requested with an absolute
+	 * expiry time which is less than base->offset. Set it to 0.
+	 */
+	if (expires < 0)
+		expires = 0;
+
+	if (expires >= cpu_base->expires_next)
+		return;
+
+	/* Update the pointer to the next expiring timer */
+	cpu_base->next_timer = timer;
+
+	/*
+	 * If a hang was detected in the last timer interrupt then we
+	 * do not schedule a timer which is earlier than the expiry
+	 * which we enforced in the hang detection. We want the system
+	 * to make progress.
+	 */
+	if (cpu_base->hang_detected)
+		return;
+
+	/*
+	 * Program the timer hardware. We enforce the expiry for
+	 * events which are already in the past.
+	 */
+	cpu_base->expires_next = expires;
+	tick_program_event(expires, 1);
+}
+
+/*
  * Clock realtime was set
  *
  * Change the offset of the realtime clock vs. the monotonic

[PATCH v2 18/37] hrtimer: Reduce conditional code and make hrtimer_force_reprogramm() unconditional

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Reduce-conditional-code-and-make-hrtimer_force_reprogramm---unconditional.patch --]
[-- Type: text/plain, Size: 2937 bytes --]

hrtimer_force_reprogram() needs to be available unconditionally for softirq
based hrtimers. Move the function and all required struct members out of
the CONFIG_HIGH_RES_TIMERS #ifdef.

There is no functional change because hrtimer_force_reprogram() is
only invoked when hrtimer_cpu_base.hres_active is true and
CONFIG_HIGH_RES_TIMERS=y. Making it unconditional increases the text
size for the CONFIG_HIGH_RES_TIMERS=n case slightly, but avoids
replication of that code for the upcoming softirq based hrtimers
support. Most of the code gets eliminated in the
CONFIG_HIGH_RES_TIMERS=n case by the compiler.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |   58 ++++++++++++++++++++++++--------------------------
 1 file changed, 28 insertions(+), 30 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -520,34 +520,6 @@ static inline int hrtimer_hres_active(vo
 	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
 }
 
-/* High resolution timer related functions */
-#ifdef CONFIG_HIGH_RES_TIMERS
-
-/*
- * High resolution timer enabled ?
- */
-static bool hrtimer_hres_enabled __read_mostly  = true;
-unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
-EXPORT_SYMBOL_GPL(hrtimer_resolution);
-
-/*
- * Enable / Disable high resolution mode
- */
-static int __init setup_hrtimer_hres(char *str)
-{
-	return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
-}
-
-__setup("highres=", setup_hrtimer_hres);
-
-/*
- * hrtimer_high_res_enabled - query, if the highres mode is enabled
- */
-static inline int hrtimer_is_hres_enabled(void)
-{
-	return hrtimer_hres_enabled;
-}
-
 /*
  * Reprogram the event source with checking both queues for the
  * next event
@@ -588,6 +560,34 @@ hrtimer_force_reprogram(struct hrtimer_c
 	tick_program_event(cpu_base->expires_next, 1);
 }
 
+/* High resolution timer related functions */
+#ifdef CONFIG_HIGH_RES_TIMERS
+
+/*
+ * High resolution timer enabled ?
+ */
+static bool hrtimer_hres_enabled __read_mostly  = true;
+unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
+EXPORT_SYMBOL_GPL(hrtimer_resolution);
+
+/*
+ * Enable / Disable high resolution mode
+ */
+static int __init setup_hrtimer_hres(char *str)
+{
+	return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
+}
+
+__setup("highres=", setup_hrtimer_hres);
+
+/*
+ * hrtimer_high_res_enabled - query, if the highres mode is enabled
+ */
+static inline int hrtimer_is_hres_enabled(void)
+{
+	return hrtimer_hres_enabled;
+}
+
 /*
  * Retrigger next event is called after clock was set
  *
@@ -646,8 +646,6 @@ void clock_was_set_delayed(void)
 
 static inline int hrtimer_is_hres_enabled(void) { return 0; }
 static inline void hrtimer_switch_to_hres(void) { }
-static inline void
-hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
 static inline void retrigger_next_event(void *arg) { }
 
 #endif /* CONFIG_HIGH_RES_TIMERS */

[PATCH v2 19/37] hrtimer: Unify handling of hrtimer remove

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Unify-handling-of-hrtimer-remove.patch --]
[-- Type: text/plain, Size: 3094 bytes --]

When the first hrtimer on the current CPU is removed,
hrtimer_force_reprogram() is invoked but only when
CONFIG_HIGH_RES_TIMERS=y and hrtimer_cpu_base.hres_active is set.

hrtimer_force_reprogram() updates hrtimer_cpu_base.expires_next and
reprograms the clock event device. When CONFIG_HIGH_RES_TIMERS=y and
hrtimer_cpu_base.hres_active is set, a pointless hrtimer interrupt can be
prevented.

hrtimer_check_target() makes the 'can remote enqueue' decision. As soon as
hrtimer_check_target() is unconditionally available and
hrtimer_cpu_base.expires_next is updated by hrtimer_reprogram(),
hrtimer_force_reprogram() needs to be available unconditionally as well to
prevent the following scenario with CONFIG_HIGH_RES_TIMERS=n:

- the first hrtimer on this CPU is removed and hrtimer_force_reprogram() is
  not executed

- CPU goes idle (next timer is calculated and hrtimers are taken into
  account)

- a hrtimer is enqueued remote on the idle CPU: hrtimer_check_target()
  compares expiry value and hrtimer_cpu_base.expires_next. The expiry value
  is after expires_next, so the hrtimer is enqueued. This timer will fire
  late, if it expires before the effective first hrtimer on this CPU and
  the comparison was with an outdated expires_next value.

To prevent this scenario, make hrtimer_force_reprogram() unconditional
except the effective reprogramming part, which gets eliminated by the
compiler in the CONFIG_HIGH_RES_TIMERS=n case.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -530,9 +530,6 @@ hrtimer_force_reprogram(struct hrtimer_c
 {
 	ktime_t expires_next;
 
-	if (!__hrtimer_hres_active(cpu_base))
-		return;
-
 	expires_next = __hrtimer_get_next_event(cpu_base);
 
 	if (skip_equal && expires_next == cpu_base->expires_next)
@@ -541,6 +538,9 @@ hrtimer_force_reprogram(struct hrtimer_c
 	cpu_base->expires_next = expires_next;
 
 	/*
+	 * If hres is not active, hardware does not have to be
+	 * reprogrammed yet.
+	 *
 	 * If a hang was detected in the last timer interrupt then we
 	 * leave the hang delay active in the hardware. We want the
 	 * system to make progress. That also prevents the following
@@ -554,7 +554,7 @@ hrtimer_force_reprogram(struct hrtimer_c
 	 * set. So we'd effectivly block all timers until the T2 event
 	 * fires.
 	 */
-	if (cpu_base->hang_detected)
+	if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
 		return;
 
 	tick_program_event(cpu_base->expires_next, 1);
@@ -855,7 +855,6 @@ static void __remove_hrtimer(struct hrti
 	if (!timerqueue_del(&base->active, &timer->node))
 		cpu_base->active_bases &= ~(1 << base->index);
 
-#ifdef CONFIG_HIGH_RES_TIMERS
 	/*
 	 * Note: If reprogram is false we do not update
 	 * cpu_base->next_timer. This happens when we remove the first
@@ -866,7 +865,6 @@ static void __remove_hrtimer(struct hrti
 	 */
 	if (reprogram && timer == cpu_base->next_timer)
 		hrtimer_force_reprogram(cpu_base, 1);
-#endif
 }
 
 /*

[PATCH v2 20/37] hrtimer: Unify handling of remote enqueue

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--enable-reprogram-gleich.patch --]
[-- Type: text/plain, Size: 3211 bytes --]

hrtimer_reprogram() is conditionally invoked from hrtimer_start_range_ns()
when hrtimer_cpu_base.hres_active is true.

In the !hres_active case there is a special condition for the nohz_active
case:

  If the newly enqueued timer expires before the first expiring timer on a
  remote CPU then the remote CPU needs to be notified and woken up from a
  NOHZ idle sleep to take the new first expiring timer into account.

Previous changes have already established the prerequisites to make the
remote enqueue behaviour the same whether high resolution mode is active or
not:

  If the to be enqueued timer expires before the first expiring timer on a
  remote CPU, then it cannot be enqueued there.

This was done for the high resolution mode because there is no way to
access the remote CPU timer hardware. The same is true for NOHZ, but was
handled differently by unconditionally enqueuing the timer and waking up
the remote CPU so it can reprogram its timer. Again there is no compelling
reason for this difference.

hrtimer_check_target(), which makes the 'can remote enqueue' decision is
already unconditional, but not yet functional because nothing updates
hrtimer_cpu_base.expires_next in the !hres_active case.

To unify this the following changes are required:

 1) Make the store of the new first expiry time unconditonal in
    hrtimer_reprogram() and check __hrtimer_hres_active() before proceeding
    to the actual hardware access. This check also lets the compiler
    eliminate the rest of the function in case of CONFIG_HIGH_RES_TIMERS=n.

 2) Invoke hrtimer_reprogram() unconditionally from
    hrtimer_start_range_ns()

 3) Remove the remote wakeup special case for the !high_res && nohz_active
    case.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |   19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -694,21 +694,24 @@ static void hrtimer_reprogram(struct hrt
 
 	/* Update the pointer to the next expiring timer */
 	cpu_base->next_timer = timer;
+	cpu_base->expires_next = expires;
 
 	/*
+	 * If hres is not active, hardware does not have to be
+	 * programmed yet.
+	 *
 	 * If a hang was detected in the last timer interrupt then we
 	 * do not schedule a timer which is earlier than the expiry
 	 * which we enforced in the hang detection. We want the system
 	 * to make progress.
 	 */
-	if (cpu_base->hang_detected)
+	if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
 		return;
 
 	/*
 	 * Program the timer hardware. We enforce the expiry for
 	 * events which are already in the past.
 	 */
-	cpu_base->expires_next = expires;
 	tick_program_event(expires, 1);
 }
 
@@ -947,16 +950,8 @@ void hrtimer_start_range_ns(struct hrtim
 	if (!leftmost)
 		goto unlock;
 
-	if (!hrtimer_is_hres_active(timer)) {
-		/*
-		 * Kick to reschedule the next tick to handle the new timer
-		 * on dynticks target.
-		 */
-		if (new_base->cpu_base->nohz_active)
-			wake_up_nohz_cpu(new_base->cpu_base->cpu);
-	} else {
-		hrtimer_reprogram(timer, new_base);
-	}
+	hrtimer_reprogram(timer, new_base);
+
 unlock:
 	unlock_hrtimer_base(timer, &flags);
 }

[PATCH v2 21/37] hrtimer: Make remote enqueue decision less restrictive

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--check-target-fix.patch --]
[-- Type: text/plain, Size: 938 bytes --]

The current decision whether a timer can be queued on a remote CPU checks
for timer->expiry <= remote_cpu_base.expires_next.

This is too restrictive because a timer with the same expiry time as an
existing timer will be enqueued on right-hand size of the existing timer
inside the rbtree, i.e. behind the first expiring timer.

So its safe to allow enqueuing timers with the same expiry time as the
first expiring timer on a remote CPU base.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -168,7 +168,7 @@ hrtimer_check_target(struct hrtimer *tim
 	ktime_t expires;
 
 	expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
-	return expires <= new_base->cpu_base->expires_next;
+	return expires < new_base->cpu_base->expires_next;
 }
 
 #ifdef CONFIG_NO_HZ_COMMON

[PATCH v2 22/37] hrtimer: Remove base argument from hrtimer_reprogram()

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Simplify-hrtimer_reprogram---call.patch --]
[-- Type: text/plain, Size: 1774 bytes --]

hrtimer_reprogram() must have access to the hrtimer_clock_base of the new
first expiring timer to access hrtimer_clock_base.offset for adjusting the
expiry time to CLOCK_MONOTONIC. This is required to evaluate whether the
new left most timer in the hrtimer_clock_base is the first expiring timer
of all clock bases in a hrtimer_cpu_base.

The only user of hrtimer_reprogram() is hrtimer_start_range_ns(), which has
a pointer to hrtimer_clock_base already and hands it in as an argument. But
hrtimer_start_range_ns() will be split for the upcoming support for softirq
based hrtimers to avoid code duplication and will lose the direct access to
the clock base pointer.

Instead of handing in timer and timer->base as an argument remove the base
argument from hrtimer_reprogram() and retrieve the clock base internally.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -657,10 +657,10 @@ static inline void retrigger_next_event(
  *
  * Called with interrupts disabled and base->cpu_base.lock held
  */
-static void hrtimer_reprogram(struct hrtimer *timer,
-			      struct hrtimer_clock_base *base)
+static void hrtimer_reprogram(struct hrtimer *timer)
 {
 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+	struct hrtimer_clock_base *base = timer->base;
 	ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 
 	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
@@ -950,7 +950,7 @@ void hrtimer_start_range_ns(struct hrtim
 	if (!leftmost)
 		goto unlock;
 
-	hrtimer_reprogram(timer, new_base);
+	hrtimer_reprogram(timer);
 
 unlock:
 	unlock_hrtimer_base(timer, &flags);

[PATCH v2 23/37] hrtimer: Split hrtimer_start_range_ns()

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Split_out_code_from_hrtimer_start_range_ns_for_reuse.patch --]
[-- Type: text/plain, Size: 2352 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

Preparatory patch for softirq based hrtimers to avoid code duplication. No
functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |   44 ++++++++++++++++++++++++--------------------
 1 file changed, 24 insertions(+), 20 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -916,22 +916,11 @@ static inline ktime_t hrtimer_update_low
 	return tim;
 }
 
-/**
- * hrtimer_start_range_ns - (re)start an hrtimer
- * @timer:	the timer to be added
- * @tim:	expiry time
- * @delta_ns:	"slack" range for the timer
- * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
- *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED)
- */
-void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
-			    u64 delta_ns, const enum hrtimer_mode mode)
+static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
+				    u64 delta_ns, const enum hrtimer_mode mode,
+				    struct hrtimer_clock_base *base)
 {
-	struct hrtimer_clock_base *base, *new_base;
-	unsigned long flags;
-	int leftmost;
-
-	base = lock_hrtimer_base(timer, &flags);
+	struct hrtimer_clock_base *new_base;
 
 	/* Remove an active timer from the queue: */
 	remove_hrtimer(timer, base, true);
@@ -946,13 +935,28 @@ void hrtimer_start_range_ns(struct hrtim
 	/* Switch the timer base, if necessary: */
 	new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
 
-	leftmost = enqueue_hrtimer(timer, new_base, mode);
-	if (!leftmost)
-		goto unlock;
+	return enqueue_hrtimer(timer, new_base, mode);
+}
+
+/**
+ * hrtimer_start_range_ns - (re)start an hrtimer
+ * @timer:	the timer to be added
+ * @tim:	expiry time
+ * @delta_ns:	"slack" range for the timer
+ * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
+ *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED)
+ */
+void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
+			    u64 delta_ns, const enum hrtimer_mode mode)
+{
+	struct hrtimer_clock_base *base;
+	unsigned long flags;
+
+	base = lock_hrtimer_base(timer, &flags);
 
-	hrtimer_reprogram(timer);
+	if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
+		hrtimer_reprogram(timer);
 
-unlock:
 	unlock_hrtimer_base(timer, &flags);
 }
 EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);

[PATCH v2 24/37] hrtimer: Split __hrtimer_get_next_event()

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Split_out_code_from___hrtimer_get_next_event_for_reuse.patch --]
[-- Type: text/plain, Size: 1540 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

Preparatory patch for softirq based hrtimers to avoid code duplication. No
functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |   20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -466,13 +466,13 @@ static struct hrtimer_clock_base *
 #define for_each_active_base(base, cpu_base, active)	\
 	while ((base = __next_base((cpu_base), &(active))))
 
-static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
+static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
+					 unsigned int active,
+					 ktime_t expires_next)
 {
 	struct hrtimer_clock_base *base;
-	unsigned int active = cpu_base->active_bases;
-	ktime_t expires, expires_next = KTIME_MAX;
+	ktime_t expires;
 
-	cpu_base->next_timer = NULL;
 	for_each_active_base(base, cpu_base, active) {
 		struct timerqueue_node *next;
 		struct hrtimer *timer;
@@ -494,6 +494,18 @@ static ktime_t __hrtimer_get_next_event(
 		expires_next = 0;
 	return expires_next;
 }
+
+static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
+{
+	unsigned int active = cpu_base->active_bases;
+	ktime_t expires_next = KTIME_MAX;
+
+	cpu_base->next_timer = NULL;
+
+	expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
+
+	return expires_next;
+}
 #endif
 
 static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)

[PATCH v2 25/37] hrtimer: Use irqsave/irqrestore around __run_hrtimer()

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer--Change-locking.patch --]
[-- Type: text/plain, Size: 4784 bytes --]

__run_hrtimer() is called with the hrtimer_cpu_base.lock held and
interrupts disabled. Before invoking the timer callback the base lock is
dropped, but interrupts stay disabled.

The upcoming support for softirq based hrtimers requires that interrupts
are enabled before the timer callback is invoked.

To avoid code duplication, take hrtimer_cpu_base.lock with
raw_spin_lock_irqsave(flags) at the call site and hand in the flags as
argument. So raw_spin_unlock_irqrestore() before the callback invocation
will either keep interrupts disabled in interrupt context or restore to
interrupt enabled state when called from softirq context.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |   31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1171,7 +1171,8 @@ EXPORT_SYMBOL_GPL(hrtimer_active);
 
 static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
 			  struct hrtimer_clock_base *base,
-			  struct hrtimer *timer, ktime_t *now)
+			  struct hrtimer *timer, ktime_t *now,
+			  unsigned long flags)
 {
 	enum hrtimer_restart (*fn)(struct hrtimer *);
 	int restart;
@@ -1206,11 +1207,11 @@ static void __run_hrtimer(struct hrtimer
 	 * protected against migration to a different CPU even if the lock
 	 * is dropped.
 	 */
-	raw_spin_unlock(&cpu_base->lock);
+	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 	trace_hrtimer_expire_entry(timer, now);
 	restart = fn(timer);
 	trace_hrtimer_expire_exit(timer);
-	raw_spin_lock(&cpu_base->lock);
+	raw_spin_lock_irq(&cpu_base->lock);
 
 	/*
 	 * Note: We clear the running state after enqueue_hrtimer and
@@ -1238,7 +1239,8 @@ static void __run_hrtimer(struct hrtimer
 	base->running = NULL;
 }
 
-static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
+static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
+				 unsigned long flags)
 {
 	struct hrtimer_clock_base *base;
 	unsigned int active = cpu_base->active_bases;
@@ -1269,7 +1271,7 @@ static void __hrtimer_run_queues(struct
 			if (basenow < hrtimer_get_softexpires_tv64(timer))
 				break;
 
-			__run_hrtimer(cpu_base, base, timer, &basenow);
+			__run_hrtimer(cpu_base, base, timer, &basenow, flags);
 		}
 	}
 }
@@ -1284,13 +1286,14 @@ void hrtimer_interrupt(struct clock_even
 {
 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
 	ktime_t expires_next, now, entry_time, delta;
+	unsigned long flags;
 	int retries = 0;
 
 	BUG_ON(!cpu_base->hres_active);
 	cpu_base->nr_events++;
 	dev->next_event = KTIME_MAX;
 
-	raw_spin_lock(&cpu_base->lock);
+	raw_spin_lock_irqsave(&cpu_base->lock, flags);
 	entry_time = now = hrtimer_update_base(cpu_base);
 retry:
 	cpu_base->in_hrtirq = 1;
@@ -1303,7 +1306,7 @@ void hrtimer_interrupt(struct clock_even
 	 */
 	cpu_base->expires_next = KTIME_MAX;
 
-	__hrtimer_run_queues(cpu_base, now);
+	__hrtimer_run_queues(cpu_base, now, flags);
 
 	/* Reevaluate the clock bases for the next expiry */
 	expires_next = __hrtimer_get_next_event(cpu_base);
@@ -1313,7 +1316,7 @@ void hrtimer_interrupt(struct clock_even
 	 */
 	cpu_base->expires_next = expires_next;
 	cpu_base->in_hrtirq = 0;
-	raw_spin_unlock(&cpu_base->lock);
+	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 
 	/* Reprogramming necessary ? */
 	if (!tick_program_event(expires_next, 0)) {
@@ -1334,7 +1337,7 @@ void hrtimer_interrupt(struct clock_even
 	 * Acquire base lock for updating the offsets and retrieving
 	 * the current time.
 	 */
-	raw_spin_lock(&cpu_base->lock);
+	raw_spin_lock_irqsave(&cpu_base->lock, flags);
 	now = hrtimer_update_base(cpu_base);
 	cpu_base->nr_retries++;
 	if (++retries < 3)
@@ -1347,7 +1350,8 @@ void hrtimer_interrupt(struct clock_even
 	 */
 	cpu_base->nr_hangs++;
 	cpu_base->hang_detected = 1;
-	raw_spin_unlock(&cpu_base->lock);
+	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+
 	delta = ktime_sub(now, entry_time);
 	if ((unsigned int)delta > cpu_base->max_hang_time)
 		cpu_base->max_hang_time = (unsigned int) delta;
@@ -1389,6 +1393,7 @@ static inline void __hrtimer_peek_ahead_
 void hrtimer_run_queues(void)
 {
 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+	unsigned long flags;
 	ktime_t now;
 
 	if (__hrtimer_hres_active(cpu_base))
@@ -1406,10 +1411,10 @@ void hrtimer_run_queues(void)
 		return;
 	}
 
-	raw_spin_lock(&cpu_base->lock);
+	raw_spin_lock_irqsave(&cpu_base->lock, flags);
 	now = hrtimer_update_base(cpu_base);
-	__hrtimer_run_queues(cpu_base, now);
-	raw_spin_unlock(&cpu_base->lock);
+	__hrtimer_run_queues(cpu_base, now, flags);
+	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 }
 
 /*

[PATCH v2 26/37] hrtimer: Add clock bases and hrtimer mode for soft irq context

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Add_clock_bases_for_soft_irq_context.patch --]
[-- Type: text/plain, Size: 3435 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

hrtimer callback functions are always executed in hard interrupt
context. Users of hrtimer which need their timer function to be executed
in soft interrupt context, make use of tasklets to get the proper context.

Add additional hrtimer clock bases for timers which must expire in softirq
context, so the detour via the tasklet can be avoided. This is also
required for RT, where the majority of hrtimer is moved into softirq
hrtimer context.

The selection of the expiry mode happens via a mode bit. Introduce
HRTIMER_MODE_SOFT and the matching combinations with the ABS/REL/PINNED
bits and update the decoding of hrtimer_mode in tracepoints.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>

---
 include/linux/hrtimer.h      |   14 ++++++++++++++
 include/trace/events/timer.h |    6 +++++-
 kernel/time/hrtimer.c        |   20 ++++++++++++++++++++
 3 files changed, 39 insertions(+), 1 deletion(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -33,14 +33,24 @@ struct hrtimer_cpu_base;
  * HRTIMER_MODE_REL		- Time value is relative to now
  * HRTIMER_MODE_PINNED		- Timer is bound to CPU (is only considered
  *				  when starting the timer)
+ * HRTIMER_MODE_SOFT		- Timer callback function will be executed in
+ *				  soft irq context
  */
 enum hrtimer_mode {
 	HRTIMER_MODE_ABS	= 0x00,
 	HRTIMER_MODE_REL	= 0x01,
 	HRTIMER_MODE_PINNED	= 0x02,
+	HRTIMER_MODE_SOFT	= 0x04,
 
 	HRTIMER_MODE_ABS_PINNED = HRTIMER_MODE_ABS | HRTIMER_MODE_PINNED,
 	HRTIMER_MODE_REL_PINNED = HRTIMER_MODE_REL | HRTIMER_MODE_PINNED,
+
+	HRTIMER_MODE_ABS_SOFT	= HRTIMER_MODE_ABS | HRTIMER_MODE_SOFT,
+	HRTIMER_MODE_REL_SOFT	= HRTIMER_MODE_REL | HRTIMER_MODE_SOFT,
+
+	HRTIMER_MODE_ABS_PINNED_SOFT = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_SOFT,
+	HRTIMER_MODE_REL_PINNED_SOFT = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_SOFT,
+
 };
 
 /*
@@ -151,6 +161,10 @@ enum  hrtimer_base_type {
 	HRTIMER_BASE_REALTIME,
 	HRTIMER_BASE_BOOTTIME,
 	HRTIMER_BASE_TAI,
+	HRTIMER_BASE_MONOTONIC_SOFT,
+	HRTIMER_BASE_REALTIME_SOFT,
+	HRTIMER_BASE_BOOTTIME_SOFT,
+	HRTIMER_BASE_TAI_SOFT,
 	HRTIMER_MAX_CLOCK_BASES,
 };
 
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -147,7 +147,11 @@ DEFINE_EVENT(timer_class, timer_cancel,
 		{ HRTIMER_MODE_ABS,		"ABS"		},	\
 		{ HRTIMER_MODE_REL,		"REL"		},	\
 		{ HRTIMER_MODE_ABS_PINNED,	"ABS|PINNED"	},	\
-		{ HRTIMER_MODE_REL_PINNED,	"REL|PINNED"	})
+		{ HRTIMER_MODE_REL_PINNED,	"REL|PINNED"	},	\
+		{ HRTIMER_MODE_ABS_SOFT,	"ABS|SOFT"	},	\
+		{ HRTIMER_MODE_REL_SOFT,	"REL|SOFT"	},	\
+		{ HRTIMER_MODE_ABS_PINNED_SOFT,	"ABS|PINNED|SOFT" },	\
+		{ HRTIMER_MODE_REL_PINNED_SOFT,	"REL|PINNED|SOFT" })
 
 /**
  * hrtimer_init - called when the hrtimer is initialized
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -92,6 +92,26 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base,
 			.clockid = CLOCK_TAI,
 			.get_time = &ktime_get_clocktai,
 		},
+		{
+			.index = HRTIMER_BASE_MONOTONIC_SOFT,
+			.clockid = CLOCK_MONOTONIC,
+			.get_time = &ktime_get,
+		},
+		{
+			.index = HRTIMER_BASE_REALTIME_SOFT,
+			.clockid = CLOCK_REALTIME,
+			.get_time = &ktime_get_real,
+		},
+		{
+			.index = HRTIMER_BASE_BOOTTIME_SOFT,
+			.clockid = CLOCK_BOOTTIME,
+			.get_time = &ktime_get_boottime,
+		},
+		{
+			.index = HRTIMER_BASE_TAI_SOFT,
+			.clockid = CLOCK_TAI,
+			.get_time = &ktime_get_clocktai,
+		},
 	}
 };
 

[PATCH v2 27/37] hrtimer: Prepare handling of hard and softirq based hrtimers

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Allow_function_reuse_for_softirq_based_hrtimer.patch --]
[-- Type: text/plain, Size: 3793 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

The softirq based hrtimer can utilize most of the existing hrtimers
functions, but need to operate on a different data set.

Add an active_mask argument to various functions so the hard and soft bases
can be selected. Fixup the existing callers and hand in the ACTIVE_HARD
mask.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |   38 +++++++++++++++++++++++++++++---------
 1 file changed, 29 insertions(+), 9 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -60,6 +60,15 @@
 #include "tick-internal.h"
 
 /*
+ * Masks for selecting the soft and hard context timers from
+ * cpu_base->active
+ */
+#define MASK_SHIFT		(HRTIMER_BASE_MONOTONIC_SOFT)
+#define HRTIMER_ACTIVE_HARD	((1U << MASK_SHIFT) - 1)
+#define HRTIMER_ACTIVE_SOFT	(HRTIMER_ACTIVE_HARD << MASK_SHIFT)
+#define HRTIMER_ACTIVE_ALL	(HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
+
+/*
  * The timer bases:
  *
  * There are more clockids than hrtimer bases. Thus, we index
@@ -515,13 +524,24 @@ static ktime_t __hrtimer_next_event_base
 	return expires_next;
 }
 
-static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
+/*
+ * Recomputes cpu_base::*next_timer and returns the earliest expires_next but
+ * does not set cpu_base::*expires_next, that is done by hrtimer_reprogram.
+ *
+ * @active_mask must be one of:
+ *  - HRTIMER_ACTIVE,
+ *  - HRTIMER_ACTIVE_SOFT, or
+ *  - HRTIMER_ACTIVE_HARD.
+ */
+static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base,
+					unsigned int active_mask)
 {
-	unsigned int active = cpu_base->active_bases;
+	unsigned int active;
 	ktime_t expires_next = KTIME_MAX;
 
 	cpu_base->next_timer = NULL;
 
+	active = cpu_base->active_bases & active_mask;
 	expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
 
 	return expires_next;
@@ -562,7 +582,7 @@ hrtimer_force_reprogram(struct hrtimer_c
 {
 	ktime_t expires_next;
 
-	expires_next = __hrtimer_get_next_event(cpu_base);
+	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
 
 	if (skip_equal && expires_next == cpu_base->expires_next)
 		return;
@@ -1086,7 +1106,7 @@ u64 hrtimer_get_next_event(void)
 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
 
 	if (!__hrtimer_hres_active(cpu_base))
-		expires = __hrtimer_get_next_event(cpu_base);
+		expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
 
 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 
@@ -1260,10 +1280,10 @@ static void __run_hrtimer(struct hrtimer
 }
 
 static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
-				 unsigned long flags)
+				 unsigned long flags, unsigned int active_mask)
 {
 	struct hrtimer_clock_base *base;
-	unsigned int active = cpu_base->active_bases;
+	unsigned int active = cpu_base->active_bases & active_mask;
 
 	for_each_active_base(base, cpu_base, active) {
 		struct timerqueue_node *node;
@@ -1326,10 +1346,10 @@ void hrtimer_interrupt(struct clock_even
 	 */
 	cpu_base->expires_next = KTIME_MAX;
 
-	__hrtimer_run_queues(cpu_base, now, flags);
+	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
 
 	/* Reevaluate the clock bases for the next expiry */
-	expires_next = __hrtimer_get_next_event(cpu_base);
+	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
 	/*
 	 * Store the new expiry value so the migration code can verify
 	 * against it.
@@ -1433,7 +1453,7 @@ void hrtimer_run_queues(void)
 
 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
 	now = hrtimer_update_base(cpu_base);
-	__hrtimer_run_queues(cpu_base, now, flags);
+	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 }
 

[PATCH v2 28/37] hrtimer: Implement support for softirq based hrtimers

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Implementation_of_softirq_hrtimer_handling.patch --]
[-- Type: text/plain, Size: 16244 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

hrtimer callbacks are always invoked in hard interrupt context. Several
users in tree require soft interrupt context for their callbacks and
achieve this by combining a hrtimer with a tasklet. The hrtimer schedules
the tasklet in hard interrupt context and the tasklet callback gets invoked
in softirq context later.

That's suboptimal and aside of that the real-time patch moves most of the
hrtimers into softirq context. So adding native support for hrtimers
expiring in softirq context is a valuable extension for both mainline and
the RT patch set.

Each valid hrtimer clock id has two associated hrtimer clock bases: one for
timers expiring in hardirq context and one for timers expiring in softirq
context.

Implement the functionality to associate a hrtimer with the hard or softirq
related clock bases and update the relevant functions to take them into
account when the next expiry time needs to be evaluated.

Add a check into the hard interrupt context handler functions to check
whether the first expiring softirq based timer has expired. If it's expired
the softirq is raised and the accounting of softirq based timers to
evaluate the next expiry time for programming the timer hardware is skipped
until the softirq processing has finished. At the end of the softirq
processing the regular processing is resumed.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/hrtimer.h |   14 +++
 kernel/time/hrtimer.c   |  191 ++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 174 insertions(+), 31 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -113,6 +113,7 @@ struct hrtimer {
 	struct hrtimer_clock_base	*base;
 	u8				state;
 	u8				is_rel;
+	u8				is_soft;
 };
 
 /**
@@ -177,6 +178,8 @@ enum  hrtimer_base_type {
  * @clock_was_set_seq:	Sequence counter of clock was set events
  * @migration_enabled:	The migration of hrtimers to other cpus is enabled
  * @nohz_active:	The nohz functionality is enabled
+ * @softirq_activated:	displays, if the softirq is raised - update of softirq
+ *			related settings is not required then.
  * @in_hrtirq:		hrtimer_interrupt() is currently executing
  * @hres_active:	State of high resolution mode
  * @hang_detected:	The last hrtimer interrupt detected a hang
@@ -185,8 +188,11 @@ enum  hrtimer_base_type {
  * @nr_hangs:		Total number of hrtimer interrupt hangs
  * @max_hang_time:	Maximum time spent in hrtimer_interrupt
  * @expires_next:	absolute time of the next event, is required for remote
- *			hrtimer enqueue
+ *			hrtimer enqueue; it is the total first expiry time (hard
+ *			and soft hrtimer are taken into account)
  * @next_timer:		Pointer to the first expiring timer
+ * @softirq_expires_next: Time to check, if soft queues needs also to be expired
+ * @softirq_next_timer: Pointer to the first expiring softirq based timer
  * @clock_base:		array of clock bases for this cpu
  *
  * Note: next_timer is just an optimization for __remove_hrtimer().
@@ -200,6 +206,7 @@ struct hrtimer_cpu_base {
 	unsigned int			clock_was_set_seq;
 	unsigned int			migration_enabled	: 1,
 					nohz_active		: 1,
+					softirq_activated	: 1,
 					in_hrtirq		: 1,
 					hres_active		: 1,
 					hang_detected		: 1;
@@ -211,6 +218,8 @@ struct hrtimer_cpu_base {
 #endif
 	ktime_t				expires_next;
 	struct hrtimer			*next_timer;
+	ktime_t				softirq_expires_next;
+	struct hrtimer			*softirq_next_timer;
 	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
 } ____cacheline_aligned;
 
@@ -383,7 +392,8 @@ extern void hrtimer_start_range_ns(struc
  * @timer:	the timer to be added
  * @tim:	expiry time
  * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
- *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED)
+ *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
+ *		softirq based mode is considered for debug purpose only!
  */
 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
 				 const enum hrtimer_mode mode)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -68,6 +68,9 @@
 #define HRTIMER_ACTIVE_SOFT	(HRTIMER_ACTIVE_HARD << MASK_SHIFT)
 #define HRTIMER_ACTIVE_ALL	(HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
 
+/* Define for debug mode check */
+#define HRTIMER_MODECHECK	true
+
 /*
  * The timer bases:
  *
@@ -418,8 +421,17 @@ static inline void debug_hrtimer_init(st
 	debug_object_init(timer, &hrtimer_debug_descr);
 }
 
-static inline void debug_hrtimer_activate(struct hrtimer *timer)
+static inline void debug_hrtimer_activate(struct hrtimer *timer,
+					  enum hrtimer_mode mode,
+					  bool modecheck)
 {
+	/*
+	 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
+	 * match, when a timer is started via__hrtimer_start_range_ns().
+	 */
+	if (modecheck)
+		WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
+
 	debug_object_activate(timer, &hrtimer_debug_descr);
 }
 
@@ -451,8 +463,11 @@ void destroy_hrtimer_on_stack(struct hrt
 EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
 
 #else
+
 static inline void debug_hrtimer_init(struct hrtimer *timer) { }
-static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
+static inline void debug_hrtimer_activate(struct hrtimer *timer,
+					  enum hrtimer_mode mode,
+					  bool modecheck) { }
 static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
 #endif
 
@@ -465,9 +480,10 @@ debug_init(struct hrtimer *timer, clocki
 }
 
 static inline void debug_activate(struct hrtimer *timer,
-				  enum hrtimer_mode mode)
+				  enum hrtimer_mode mode,
+				  bool modecheck)
 {
-	debug_hrtimer_activate(timer);
+	debug_hrtimer_activate(timer, mode, modecheck);
 	trace_hrtimer_start(timer, mode);
 }
 
@@ -477,7 +493,6 @@ static inline void debug_deactivate(stru
 	trace_hrtimer_cancel(timer);
 }
 
-#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
 static struct hrtimer_clock_base *
 __next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
 {
@@ -511,7 +526,10 @@ static ktime_t __hrtimer_next_event_base
 		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 		if (expires < expires_next) {
 			expires_next = expires;
-			cpu_base->next_timer = timer;
+			if (timer->is_soft)
+				cpu_base->softirq_next_timer = timer;
+			else
+				cpu_base->next_timer = timer;
 		}
 	}
 	/*
@@ -528,25 +546,42 @@ static ktime_t __hrtimer_next_event_base
  * Recomputes cpu_base::*next_timer and returns the earliest expires_next but
  * does not set cpu_base::*expires_next, that is done by hrtimer_reprogram.
  *
+ * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
+ * those timers will get run whenever the softirq gets handled, at the end of
+ * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
+ *
+ * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
+ * The !softirq values are the minima across HRTIMER_ACTIVE, unless an actual
+ * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
+ *
  * @active_mask must be one of:
  *  - HRTIMER_ACTIVE,
  *  - HRTIMER_ACTIVE_SOFT, or
  *  - HRTIMER_ACTIVE_HARD.
  */
-static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base,
-					unsigned int active_mask)
+static ktime_t
+__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
 {
 	unsigned int active;
+	struct hrtimer *next_timer = NULL;
 	ktime_t expires_next = KTIME_MAX;
 
-	cpu_base->next_timer = NULL;
+	if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
+		active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
+		cpu_base->softirq_next_timer = next_timer;
+		expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
+
+		next_timer = cpu_base->softirq_next_timer;
+	}
 
-	active = cpu_base->active_bases & active_mask;
-	expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
+	if (active_mask & HRTIMER_ACTIVE_HARD) {
+		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
+		cpu_base->next_timer = next_timer;
+		expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
+	}
 
 	return expires_next;
 }
-#endif
 
 static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
 {
@@ -554,8 +589,14 @@ static inline ktime_t hrtimer_update_bas
 	ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
 	ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
 
-	return ktime_get_update_offsets_now(&base->clock_was_set_seq,
+	ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
 					    offs_real, offs_boot, offs_tai);
+
+	base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
+	base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
+	base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
+
+	return now;
 }
 
 /*
@@ -582,7 +623,17 @@ hrtimer_force_reprogram(struct hrtimer_c
 {
 	ktime_t expires_next;
 
-	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
+	/*
+	 * Find the current next expiration time.
+	 */
+	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
+
+	if (cpu_base->next_timer->is_soft) {
+		if (cpu_base->softirq_activated)
+			return;
+
+		cpu_base->softirq_expires_next = expires_next;
+	}
 
 	if (skip_equal && expires_next == cpu_base->expires_next)
 		return;
@@ -718,6 +769,27 @@ static void hrtimer_reprogram(struct hrt
 	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
 
 	/*
+	 * CLOCK_REALTIME timer might be requested with an absolute
+	 * expiry time which is less than base->offset. Set it to 0.
+	 */
+	if (expires < 0)
+		expires = 0;
+
+	if (timer->is_soft) {
+		if (cpu_base->softirq_activated)
+			return;
+
+		if (!ktime_before(expires, cpu_base->softirq_expires_next))
+			return;
+
+		cpu_base->softirq_next_timer = timer;
+		cpu_base->softirq_expires_next = expires;
+
+		if (!ktime_before(expires, cpu_base->expires_next))
+			return;
+	}
+
+	/*
 	 * If the timer is not on the current cpu, we cannot reprogram
 	 * the other cpus clock event device.
 	 */
@@ -734,13 +806,6 @@ static void hrtimer_reprogram(struct hrt
 	if (cpu_base->in_hrtirq)
 		return;
 
-	/*
-	 * CLOCK_REALTIME timer might be requested with an absolute
-	 * expiry time which is less than base->offset. Set it to 0.
-	 */
-	if (expires < 0)
-		expires = 0;
-
 	if (expires >= cpu_base->expires_next)
 		return;
 
@@ -875,9 +940,10 @@ EXPORT_SYMBOL_GPL(hrtimer_forward);
  */
 static int enqueue_hrtimer(struct hrtimer *timer,
 			   struct hrtimer_clock_base *base,
-			   enum hrtimer_mode mode)
+			   enum hrtimer_mode mode,
+			   bool modecheck)
 {
-	debug_activate(timer, mode);
+	debug_activate(timer, mode, modecheck);
 
 	base->cpu_base->active_bases |= 1 << base->index;
 
@@ -968,6 +1034,32 @@ static inline ktime_t hrtimer_update_low
 	return tim;
 }
 
+static void
+hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
+{
+	ktime_t expires;
+
+	/*
+	 * Find the next SOFT expiration.
+	 */
+	expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
+
+	/*
+	 * reprogramming needs to be triggered, even if the next soft
+	 * hrtimer expires at the same time than the next hard
+	 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
+	 */
+	if (!reprogram || expires == KTIME_MAX ||
+	    ktime_before(expires, cpu_base->expires_next))
+		return;
+
+	/*
+	 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
+	 * cpu_base->*expires_next is only set by hrtimer_reprogram()
+	 */
+	hrtimer_reprogram(cpu_base->softirq_next_timer);
+}
+
 static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 				    u64 delta_ns, const enum hrtimer_mode mode,
 				    struct hrtimer_clock_base *base)
@@ -987,7 +1079,7 @@ static int __hrtimer_start_range_ns(stru
 	/* Switch the timer base, if necessary: */
 	new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
 
-	return enqueue_hrtimer(timer, new_base, mode);
+	return enqueue_hrtimer(timer, new_base, mode, HRTIMER_MODECHECK);
 }
 
 /**
@@ -996,7 +1088,8 @@ static int __hrtimer_start_range_ns(stru
  * @tim:	expiry time
  * @delta_ns:	"slack" range for the timer
  * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
- *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED)
+ *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
+ *		softirq based mode is considered for debug purpose only!
  */
 void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 			    u64 delta_ns, const enum hrtimer_mode mode)
@@ -1106,7 +1199,7 @@ u64 hrtimer_get_next_event(void)
 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
 
 	if (!__hrtimer_hres_active(cpu_base))
-		expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
+		expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
 
 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 
@@ -1264,7 +1357,8 @@ static void __run_hrtimer(struct hrtimer
 	 */
 	if (restart != HRTIMER_NORESTART &&
 	    !(timer->state & HRTIMER_STATE_ENQUEUED))
-		enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
+		enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS,
+				!HRTIMER_MODECHECK);
 
 	/*
 	 * Separate the ->running assignment from the ->state assignment.
@@ -1316,6 +1410,23 @@ static void __hrtimer_run_queues(struct
 	}
 }
 
+static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
+{
+	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+	unsigned long flags;
+	ktime_t now;
+
+	raw_spin_lock_irqsave(&cpu_base->lock, flags);
+
+	now = hrtimer_update_base(cpu_base);
+	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
+
+	cpu_base->softirq_activated = 0;
+	hrtimer_update_softirq_timer(cpu_base, true);
+
+	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+}
+
 #ifdef CONFIG_HIGH_RES_TIMERS
 
 /*
@@ -1346,10 +1457,16 @@ void hrtimer_interrupt(struct clock_even
 	 */
 	cpu_base->expires_next = KTIME_MAX;
 
+	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
+		cpu_base->softirq_expires_next = KTIME_MAX;
+		cpu_base->softirq_activated = 1;
+		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+	}
+
 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
 
 	/* Reevaluate the clock bases for the next expiry */
-	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
+	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
 	/*
 	 * Store the new expiry value so the migration code can verify
 	 * against it.
@@ -1453,6 +1570,13 @@ void hrtimer_run_queues(void)
 
 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
 	now = hrtimer_update_base(cpu_base);
+
+	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
+		cpu_base->softirq_expires_next = KTIME_MAX;
+		cpu_base->softirq_activated = 1;
+		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+	}
+
 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 }
@@ -1634,6 +1758,7 @@ int hrtimers_prepare_cpu(unsigned int cp
 	cpu_base->cpu = cpu;
 	cpu_base->hres_active = 0;
 	cpu_base->expires_next = KTIME_MAX;
+	cpu_base->softirq_expires_next = KTIME_MAX;
 	return 0;
 }
 
@@ -1665,7 +1790,8 @@ static void migrate_hrtimer_list(struct
 		 * sort out already expired timers and reprogram the
 		 * event device.
 		 */
-		enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
+		enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS,
+				!HRTIMER_MODECHECK);
 	}
 }
 
@@ -1692,6 +1818,12 @@ int hrtimers_dead_cpu(unsigned int scpu)
 				     &new_base->clock_base[i]);
 	}
 
+	/*
+	 * The migration might have changed the first expiring softirq
+	 * timer on this CPU. Update it.
+	 */
+	hrtimer_update_softirq_timer(new_base, false);
+
 	raw_spin_unlock(&old_base->lock);
 	raw_spin_unlock(&new_base->lock);
 
@@ -1706,6 +1838,7 @@ int hrtimers_dead_cpu(unsigned int scpu)
 void __init hrtimers_init(void)
 {
 	hrtimers_prepare_cpu(smp_processor_id());
+	open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
 }
 
 /**

[PATCH v2 29/37] hrtimer: Implement SOFT/HARD clock base selection

[Anna-Maria Gleixner]

[-- Attachment #1: hrtimer_Enable_soft_and_hard_hrtimer.patch --]
[-- Type: text/plain, Size: 1989 bytes --]

From: Anna-Maria Gleixner <anna-maria@linutronix.de>

All prerequisites to handle hrtimers for expiry in either hard or soft
interrupt context are in place.

Add the missing bit in hrtimer_init() which associates the timer to the
hard or the soft irq clock base.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 kernel/time/hrtimer.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1222,8 +1222,9 @@ static inline int hrtimer_clockid_to_bas
 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 			   enum hrtimer_mode mode)
 {
+	bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
+	int base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
 	struct hrtimer_cpu_base *cpu_base;
-	int base;
 
 	memset(timer, 0, sizeof(struct hrtimer));
 
@@ -1237,7 +1238,8 @@ static void __hrtimer_init(struct hrtime
 	if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
 		clock_id = CLOCK_MONOTONIC;
 
-	base = hrtimer_clockid_to_base(clock_id);
+	base += hrtimer_clockid_to_base(clock_id);
+	timer->is_soft = softtimer;
 	timer->base = &cpu_base->clock_base[base];
 	timerqueue_init(&timer->node);
 }
@@ -1246,8 +1248,13 @@ static void __hrtimer_init(struct hrtime
  * hrtimer_init - initialize a timer to the given clock
  * @timer:	the timer to be initialized
  * @clock_id:	the clock to be used
- * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
- *		relative (HRTIMER_MODE_REL); pinned is not considered here!
+ * @mode:       The modes which are relevant for intitialization:
+ *              HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
+ *              HRTIMER_MODE_REL_SOFT
+ *
+ *              The PINNED variants of the above can be handed in,
+ *              but the PINNED bit is ignored as pinning happens
+ *              when the hrtimer is started
  */
 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 		  enum hrtimer_mode mode)

[PATCH v2 30/37] can/bcm: Replace hrtimer_tasklet with softirq based hrtimer

[Anna-Maria Gleixner]

[-- Attachment #1: canbcm_Replace_hrtimer_tasklet_with_softirq_based_hrtimer.patch --]
[-- Type: text/plain, Size: 9634 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
callback in softirq context and remove the hrtimer_tasklet.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: linux-can@vger.kernel.org
---
 net/can/bcm.c |  156 +++++++++++++++++++---------------------------------------
 1 file changed, 52 insertions(+), 104 deletions(-)

--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -102,7 +102,6 @@ struct bcm_op {
 	unsigned long frames_abs, frames_filtered;
 	struct bcm_timeval ival1, ival2;
 	struct hrtimer timer, thrtimer;
-	struct tasklet_struct tsklet, thrtsklet;
 	ktime_t rx_stamp, kt_ival1, kt_ival2, kt_lastmsg;
 	int rx_ifindex;
 	int cfsiz;
@@ -364,25 +363,34 @@ static void bcm_send_to_user(struct bcm_
 	}
 }
 
-static void bcm_tx_start_timer(struct bcm_op *op)
+static bool bcm_tx_set_expiry(struct bcm_op *op, struct hrtimer *hrt)
 {
+	ktime_t ival;
+
 	if (op->kt_ival1 && op->count)
-		hrtimer_start(&op->timer,
-			      ktime_add(ktime_get(), op->kt_ival1),
-			      HRTIMER_MODE_ABS);
+		ival = op->kt_ival1;
 	else if (op->kt_ival2)
-		hrtimer_start(&op->timer,
-			      ktime_add(ktime_get(), op->kt_ival2),
-			      HRTIMER_MODE_ABS);
+		ival = op->kt_ival2;
+	else
+		return false;
+
+	hrtimer_set_expires(hrt, ktime_add(ktime_get(), ival));
+	return true;
 }
 
-static void bcm_tx_timeout_tsklet(unsigned long data)
+static void bcm_tx_start_timer(struct bcm_op *op)
 {
-	struct bcm_op *op = (struct bcm_op *)data;
+	if (bcm_tx_set_expiry(op, &op->timer))
+		hrtimer_start_expires(&op->timer, HRTIMER_MODE_ABS_SOFT);
+}
+
+/* bcm_tx_timeout_handler - performs cyclic CAN frame transmissions */
+static enum hrtimer_restart bcm_tx_timeout_handler(struct hrtimer *hrtimer)
+{
+	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
 	struct bcm_msg_head msg_head;
 
 	if (op->kt_ival1 && (op->count > 0)) {
-
 		op->count--;
 		if (!op->count && (op->flags & TX_COUNTEVT)) {
 
@@ -399,22 +407,12 @@ static void bcm_tx_timeout_tsklet(unsign
 		}
 		bcm_can_tx(op);
 
-	} else if (op->kt_ival2)
+	} else if (op->kt_ival2) {
 		bcm_can_tx(op);
+	}
 
-	bcm_tx_start_timer(op);
-}
-
-/*
- * bcm_tx_timeout_handler - performs cyclic CAN frame transmissions
- */
-static enum hrtimer_restart bcm_tx_timeout_handler(struct hrtimer *hrtimer)
-{
-	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
-
-	tasklet_schedule(&op->tsklet);
-
-	return HRTIMER_NORESTART;
+	return bcm_tx_set_expiry(op, &op->timer) ?
+		HRTIMER_RESTART : HRTIMER_NORESTART;
 }
 
 /*
@@ -480,7 +478,7 @@ static void bcm_rx_update_and_send(struc
 		/* do not send the saved data - only start throttle timer */
 		hrtimer_start(&op->thrtimer,
 			      ktime_add(op->kt_lastmsg, op->kt_ival2),
-			      HRTIMER_MODE_ABS);
+			      HRTIMER_MODE_ABS_SOFT);
 		return;
 	}
 
@@ -539,14 +537,21 @@ static void bcm_rx_starttimer(struct bcm
 		return;
 
 	if (op->kt_ival1)
-		hrtimer_start(&op->timer, op->kt_ival1, HRTIMER_MODE_REL);
+		hrtimer_start(&op->timer, op->kt_ival1, HRTIMER_MODE_REL_SOFT);
 }
 
-static void bcm_rx_timeout_tsklet(unsigned long data)
+/* bcm_rx_timeout_handler - when the (cyclic) CAN frame reception timed out */
+static enum hrtimer_restart bcm_rx_timeout_handler(struct hrtimer *hrtimer)
 {
-	struct bcm_op *op = (struct bcm_op *)data;
+	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
 	struct bcm_msg_head msg_head;
 
+	/* if user wants to be informed, when cyclic CAN-Messages come back */
+	if ((op->flags & RX_ANNOUNCE_RESUME) && op->last_frames) {
+		/* clear received CAN frames to indicate 'nothing received' */
+		memset(op->last_frames, 0, op->nframes * op->cfsiz);
+	}
+
 	/* create notification to user */
 	msg_head.opcode  = RX_TIMEOUT;
 	msg_head.flags   = op->flags;
@@ -557,25 +562,6 @@ static void bcm_rx_timeout_tsklet(unsign
 	msg_head.nframes = 0;
 
 	bcm_send_to_user(op, &msg_head, NULL, 0);
-}
-
-/*
- * bcm_rx_timeout_handler - when the (cyclic) CAN frame reception timed out
- */
-static enum hrtimer_restart bcm_rx_timeout_handler(struct hrtimer *hrtimer)
-{
-	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
-
-	/* schedule before NET_RX_SOFTIRQ */
-	tasklet_hi_schedule(&op->tsklet);
-
-	/* no restart of the timer is done here! */
-
-	/* if user wants to be informed, when cyclic CAN-Messages come back */
-	if ((op->flags & RX_ANNOUNCE_RESUME) && op->last_frames) {
-		/* clear received CAN frames to indicate 'nothing received' */
-		memset(op->last_frames, 0, op->nframes * op->cfsiz);
-	}
 
 	return HRTIMER_NORESTART;
 }
@@ -583,14 +569,12 @@ static enum hrtimer_restart bcm_rx_timeo
 /*
  * bcm_rx_do_flush - helper for bcm_rx_thr_flush
  */
-static inline int bcm_rx_do_flush(struct bcm_op *op, int update,
-				  unsigned int index)
+static inline int bcm_rx_do_flush(struct bcm_op *op, unsigned int index)
 {
 	struct canfd_frame *lcf = op->last_frames + op->cfsiz * index;
 
 	if ((op->last_frames) && (lcf->flags & RX_THR)) {
-		if (update)
-			bcm_rx_changed(op, lcf);
+		bcm_rx_changed(op, lcf);
 		return 1;
 	}
 	return 0;
@@ -598,11 +582,8 @@ static inline int bcm_rx_do_flush(struct
 
 /*
  * bcm_rx_thr_flush - Check for throttled data and send it to the userspace
- *
- * update == 0 : just check if throttled data is available  (any irq context)
- * update == 1 : check and send throttled data to userspace (soft_irq context)
  */
-static int bcm_rx_thr_flush(struct bcm_op *op, int update)
+static int bcm_rx_thr_flush(struct bcm_op *op)
 {
 	int updated = 0;
 
@@ -611,24 +592,16 @@ static int bcm_rx_thr_flush(struct bcm_o
 
 		/* for MUX filter we start at index 1 */
 		for (i = 1; i < op->nframes; i++)
-			updated += bcm_rx_do_flush(op, update, i);
+			updated += bcm_rx_do_flush(op, i);
 
 	} else {
 		/* for RX_FILTER_ID and simple filter */
-		updated += bcm_rx_do_flush(op, update, 0);
+		updated += bcm_rx_do_flush(op, 0);
 	}
 
 	return updated;
 }
 
-static void bcm_rx_thr_tsklet(unsigned long data)
-{
-	struct bcm_op *op = (struct bcm_op *)data;
-
-	/* push the changed data to the userspace */
-	bcm_rx_thr_flush(op, 1);
-}
-
 /*
  * bcm_rx_thr_handler - the time for blocked content updates is over now:
  *                      Check for throttled data and send it to the userspace
@@ -637,9 +610,7 @@ static enum hrtimer_restart bcm_rx_thr_h
 {
 	struct bcm_op *op = container_of(hrtimer, struct bcm_op, thrtimer);
 
-	tasklet_schedule(&op->thrtsklet);
-
-	if (bcm_rx_thr_flush(op, 0)) {
+	if (bcm_rx_thr_flush(op)) {
 		hrtimer_forward(hrtimer, ktime_get(), op->kt_ival2);
 		return HRTIMER_RESTART;
 	} else {
@@ -735,23 +706,8 @@ static struct bcm_op *bcm_find_op(struct
 
 static void bcm_remove_op(struct bcm_op *op)
 {
-	if (op->tsklet.func) {
-		while (test_bit(TASKLET_STATE_SCHED, &op->tsklet.state) ||
-		       test_bit(TASKLET_STATE_RUN, &op->tsklet.state) ||
-		       hrtimer_active(&op->timer)) {
-			hrtimer_cancel(&op->timer);
-			tasklet_kill(&op->tsklet);
-		}
-	}
-
-	if (op->thrtsklet.func) {
-		while (test_bit(TASKLET_STATE_SCHED, &op->thrtsklet.state) ||
-		       test_bit(TASKLET_STATE_RUN, &op->thrtsklet.state) ||
-		       hrtimer_active(&op->thrtimer)) {
-			hrtimer_cancel(&op->thrtimer);
-			tasklet_kill(&op->thrtsklet);
-		}
-	}
+	hrtimer_cancel(&op->timer);
+	hrtimer_cancel(&op->thrtimer);
 
 	if ((op->frames) && (op->frames != &op->sframe))
 		kfree(op->frames);
@@ -979,15 +935,13 @@ static int bcm_tx_setup(struct bcm_msg_h
 		op->ifindex = ifindex;
 
 		/* initialize uninitialized (kzalloc) structure */
-		hrtimer_init(&op->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		hrtimer_init(&op->timer, CLOCK_MONOTONIC,
+			     HRTIMER_MODE_REL_SOFT);
 		op->timer.function = bcm_tx_timeout_handler;
 
-		/* initialize tasklet for tx countevent notification */
-		tasklet_init(&op->tsklet, bcm_tx_timeout_tsklet,
-			     (unsigned long) op);
-
 		/* currently unused in tx_ops */
-		hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC,
+			     HRTIMER_MODE_REL_SOFT);
 
 		/* add this bcm_op to the list of the tx_ops */
 		list_add(&op->list, &bo->tx_ops);
@@ -1150,20 +1104,14 @@ static int bcm_rx_setup(struct bcm_msg_h
 		op->rx_ifindex = ifindex;
 
 		/* initialize uninitialized (kzalloc) structure */
-		hrtimer_init(&op->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		hrtimer_init(&op->timer, CLOCK_MONOTONIC,
+			     HRTIMER_MODE_REL_SOFT);
 		op->timer.function = bcm_rx_timeout_handler;
 
-		/* initialize tasklet for rx timeout notification */
-		tasklet_init(&op->tsklet, bcm_rx_timeout_tsklet,
-			     (unsigned long) op);
-
-		hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC,
+			     HRTIMER_MODE_REL_SOFT);
 		op->thrtimer.function = bcm_rx_thr_handler;
 
-		/* initialize tasklet for rx throttle handling */
-		tasklet_init(&op->thrtsklet, bcm_rx_thr_tsklet,
-			     (unsigned long) op);
-
 		/* add this bcm_op to the list of the rx_ops */
 		list_add(&op->list, &bo->rx_ops);
 
@@ -1209,12 +1157,12 @@ static int bcm_rx_setup(struct bcm_msg_h
 			 */
 			op->kt_lastmsg = 0;
 			hrtimer_cancel(&op->thrtimer);
-			bcm_rx_thr_flush(op, 1);
+			bcm_rx_thr_flush(op);
 		}
 
 		if ((op->flags & STARTTIMER) && op->kt_ival1)
 			hrtimer_start(&op->timer, op->kt_ival1,
-				      HRTIMER_MODE_REL);
+				      HRTIMER_MODE_REL_SOFT);
 	}
 
 	/* now we can register for can_ids, if we added a new bcm_op */

[PATCH v2 31/37] mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer

[Anna-Maria Gleixner]

From: Thomas Gleixner <tglx@linutronix.de>

Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
callback in softirq context and remove the hrtimer_tasklet.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: linux-wireless@vger.kernel.org

---
 drivers/net/wireless/mac80211_hwsim.c |   44 +++++++++++++++-------------------
 1 file changed, 20 insertions(+), 24 deletions(-)

--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -537,7 +537,7 @@ struct mac80211_hwsim_data {
 	unsigned int rx_filter;
 	bool started, idle, scanning;
 	struct mutex mutex;
-	struct tasklet_hrtimer beacon_timer;
+	struct hrtimer beacon_timer;
 	enum ps_mode {
 		PS_DISABLED, PS_ENABLED, PS_AUTO_POLL, PS_MANUAL_POLL
 	} ps;
@@ -1418,7 +1418,7 @@ static void mac80211_hwsim_stop(struct i
 {
 	struct mac80211_hwsim_data *data = hw->priv;
 	data->started = false;
-	tasklet_hrtimer_cancel(&data->beacon_timer);
+	hrtimer_cancel(&data->beacon_timer);
 	wiphy_debug(hw->wiphy, "%s\n", __func__);
 }
 
@@ -1541,14 +1541,12 @@ static enum hrtimer_restart
 mac80211_hwsim_beacon(struct hrtimer *timer)
 {
 	struct mac80211_hwsim_data *data =
-		container_of(timer, struct mac80211_hwsim_data,
-			     beacon_timer.timer);
+		container_of(timer, struct mac80211_hwsim_data, beacon_timer);
 	struct ieee80211_hw *hw = data->hw;
 	u64 bcn_int = data->beacon_int;
-	ktime_t next_bcn;
 
 	if (!data->started)
-		goto out;
+		return HRTIMER_NORESTART;
 
 	ieee80211_iterate_active_interfaces_atomic(
 		hw, IEEE80211_IFACE_ITER_NORMAL,
@@ -1560,11 +1558,9 @@ mac80211_hwsim_beacon(struct hrtimer *ti
 		data->bcn_delta = 0;
 	}
 
-	next_bcn = ktime_add(hrtimer_get_expires(timer),
-			     ns_to_ktime(bcn_int * 1000));
-	tasklet_hrtimer_start(&data->beacon_timer, next_bcn, HRTIMER_MODE_ABS);
-out:
-	return HRTIMER_NORESTART;
+	hrtimer_forward(&data->beacon_timer, hrtimer_get_expires(timer),
+			ns_to_ktime(bcn_int * NSEC_PER_USEC));
+	return HRTIMER_RESTART;
 }
 
 static const char * const hwsim_chanwidths[] = {
@@ -1638,15 +1634,15 @@ static int mac80211_hwsim_config(struct
 	mutex_unlock(&data->mutex);
 
 	if (!data->started || !data->beacon_int)
-		tasklet_hrtimer_cancel(&data->beacon_timer);
-	else if (!hrtimer_is_queued(&data->beacon_timer.timer)) {
+		hrtimer_cancel(&data->beacon_timer);
+	else if (!hrtimer_is_queued(&data->beacon_timer)) {
 		u64 tsf = mac80211_hwsim_get_tsf(hw, NULL);
 		u32 bcn_int = data->beacon_int;
 		u64 until_tbtt = bcn_int - do_div(tsf, bcn_int);
 
-		tasklet_hrtimer_start(&data->beacon_timer,
-				      ns_to_ktime(until_tbtt * 1000),
-				      HRTIMER_MODE_REL);
+		hrtimer_start(&data->beacon_timer,
+			      ns_to_ktime(until_tbtt * 1000),
+			      HRTIMER_MODE_REL_SOFT);
 	}
 
 	return 0;
@@ -1709,7 +1705,7 @@ static void mac80211_hwsim_bss_info_chan
 			    info->enable_beacon, info->beacon_int);
 		vp->bcn_en = info->enable_beacon;
 		if (data->started &&
-		    !hrtimer_is_queued(&data->beacon_timer.timer) &&
+		    !hrtimer_is_queued(&data->beacon_timer) &&
 		    info->enable_beacon) {
 			u64 tsf, until_tbtt;
 			u32 bcn_int;
@@ -1717,9 +1713,9 @@ static void mac80211_hwsim_bss_info_chan
 			tsf = mac80211_hwsim_get_tsf(hw, vif);
 			bcn_int = data->beacon_int;
 			until_tbtt = bcn_int - do_div(tsf, bcn_int);
-			tasklet_hrtimer_start(&data->beacon_timer,
-					      ns_to_ktime(until_tbtt * 1000),
-					      HRTIMER_MODE_REL);
+			hrtimer_start(&data->beacon_timer,
+				      ns_to_ktime(until_tbtt * 1000),
+				      HRTIMER_MODE_REL_SOFT);
 		} else if (!info->enable_beacon) {
 			unsigned int count = 0;
 			ieee80211_iterate_active_interfaces_atomic(
@@ -1728,7 +1724,7 @@ static void mac80211_hwsim_bss_info_chan
 			wiphy_debug(hw->wiphy, "  beaconing vifs remaining: %u",
 				    count);
 			if (count == 0) {
-				tasklet_hrtimer_cancel(&data->beacon_timer);
+				hrtimer_cancel(&data->beacon_timer);
 				data->beacon_int = 0;
 			}
 		}
@@ -2720,9 +2716,9 @@ static int mac80211_hwsim_new_radio(stru
 				    data->debugfs,
 				    data, &hwsim_simulate_radar);
 
-	tasklet_hrtimer_init(&data->beacon_timer,
-			     mac80211_hwsim_beacon,
-			     CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	hrtimer_init(&data->beacon_timer, CLOCK_MONOTONIC,
+		     HRTIMER_MODE_ABS_SOFT);
+	data->beacon_timer.function = mac80211_hwsim_beacon;
 
 	spin_lock_bh(&hwsim_radio_lock);
 	list_add_tail(&data->list, &hwsim_radios);

[PATCH v2 31/37] mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer

[Anna-Maria Gleixner]

[-- Attachment #1: mac80211_hwsim_Replace_hrtimer_tasklet_with_softirq_hrtimer.patch --]
[-- Type: text/plain, Size: 4574 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
callback in softirq context and remove the hrtimer_tasklet.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: linux-wireless@vger.kernel.org

---
 drivers/net/wireless/mac80211_hwsim.c |   44 +++++++++++++++-------------------
 1 file changed, 20 insertions(+), 24 deletions(-)

--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -537,7 +537,7 @@ struct mac80211_hwsim_data {
 	unsigned int rx_filter;
 	bool started, idle, scanning;
 	struct mutex mutex;
-	struct tasklet_hrtimer beacon_timer;
+	struct hrtimer beacon_timer;
 	enum ps_mode {
 		PS_DISABLED, PS_ENABLED, PS_AUTO_POLL, PS_MANUAL_POLL
 	} ps;
@@ -1418,7 +1418,7 @@ static void mac80211_hwsim_stop(struct i
 {
 	struct mac80211_hwsim_data *data = hw->priv;
 	data->started = false;
-	tasklet_hrtimer_cancel(&data->beacon_timer);
+	hrtimer_cancel(&data->beacon_timer);
 	wiphy_debug(hw->wiphy, "%s\n", __func__);
 }
 
@@ -1541,14 +1541,12 @@ static enum hrtimer_restart
 mac80211_hwsim_beacon(struct hrtimer *timer)
 {
 	struct mac80211_hwsim_data *data =
-		container_of(timer, struct mac80211_hwsim_data,
-			     beacon_timer.timer);
+		container_of(timer, struct mac80211_hwsim_data, beacon_timer);
 	struct ieee80211_hw *hw = data->hw;
 	u64 bcn_int = data->beacon_int;
-	ktime_t next_bcn;
 
 	if (!data->started)
-		goto out;
+		return HRTIMER_NORESTART;
 
 	ieee80211_iterate_active_interfaces_atomic(
 		hw, IEEE80211_IFACE_ITER_NORMAL,
@@ -1560,11 +1558,9 @@ mac80211_hwsim_beacon(struct hrtimer *ti
 		data->bcn_delta = 0;
 	}
 
-	next_bcn = ktime_add(hrtimer_get_expires(timer),
-			     ns_to_ktime(bcn_int * 1000));
-	tasklet_hrtimer_start(&data->beacon_timer, next_bcn, HRTIMER_MODE_ABS);
-out:
-	return HRTIMER_NORESTART;
+	hrtimer_forward(&data->beacon_timer, hrtimer_get_expires(timer),
+			ns_to_ktime(bcn_int * NSEC_PER_USEC));
+	return HRTIMER_RESTART;
 }
 
 static const char * const hwsim_chanwidths[] = {
@@ -1638,15 +1634,15 @@ static int mac80211_hwsim_config(struct
 	mutex_unlock(&data->mutex);
 
 	if (!data->started || !data->beacon_int)
-		tasklet_hrtimer_cancel(&data->beacon_timer);
-	else if (!hrtimer_is_queued(&data->beacon_timer.timer)) {
+		hrtimer_cancel(&data->beacon_timer);
+	else if (!hrtimer_is_queued(&data->beacon_timer)) {
 		u64 tsf = mac80211_hwsim_get_tsf(hw, NULL);
 		u32 bcn_int = data->beacon_int;
 		u64 until_tbtt = bcn_int - do_div(tsf, bcn_int);
 
-		tasklet_hrtimer_start(&data->beacon_timer,
-				      ns_to_ktime(until_tbtt * 1000),
-				      HRTIMER_MODE_REL);
+		hrtimer_start(&data->beacon_timer,
+			      ns_to_ktime(until_tbtt * 1000),
+			      HRTIMER_MODE_REL_SOFT);
 	}
 
 	return 0;
@@ -1709,7 +1705,7 @@ static void mac80211_hwsim_bss_info_chan
 			    info->enable_beacon, info->beacon_int);
 		vp->bcn_en = info->enable_beacon;
 		if (data->started &&
-		    !hrtimer_is_queued(&data->beacon_timer.timer) &&
+		    !hrtimer_is_queued(&data->beacon_timer) &&
 		    info->enable_beacon) {
 			u64 tsf, until_tbtt;
 			u32 bcn_int;
@@ -1717,9 +1713,9 @@ static void mac80211_hwsim_bss_info_chan
 			tsf = mac80211_hwsim_get_tsf(hw, vif);
 			bcn_int = data->beacon_int;
 			until_tbtt = bcn_int - do_div(tsf, bcn_int);
-			tasklet_hrtimer_start(&data->beacon_timer,
-					      ns_to_ktime(until_tbtt * 1000),
-					      HRTIMER_MODE_REL);
+			hrtimer_start(&data->beacon_timer,
+				      ns_to_ktime(until_tbtt * 1000),
+				      HRTIMER_MODE_REL_SOFT);
 		} else if (!info->enable_beacon) {
 			unsigned int count = 0;
 			ieee80211_iterate_active_interfaces_atomic(
@@ -1728,7 +1724,7 @@ static void mac80211_hwsim_bss_info_chan
 			wiphy_debug(hw->wiphy, "  beaconing vifs remaining: %u",
 				    count);
 			if (count == 0) {
-				tasklet_hrtimer_cancel(&data->beacon_timer);
+				hrtimer_cancel(&data->beacon_timer);
 				data->beacon_int = 0;
 			}
 		}
@@ -2720,9 +2716,9 @@ static int mac80211_hwsim_new_radio(stru
 				    data->debugfs,
 				    data, &hwsim_simulate_radar);
 
-	tasklet_hrtimer_init(&data->beacon_timer,
-			     mac80211_hwsim_beacon,
-			     CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	hrtimer_init(&data->beacon_timer, CLOCK_MONOTONIC,
+		     HRTIMER_MODE_ABS_SOFT);
+	data->beacon_timer.function = mac80211_hwsim_beacon;
 
 	spin_lock_bh(&hwsim_radio_lock);
 	list_add_tail(&data->list, &hwsim_radios);

[PATCH v2 32/37] xfrm: Replace hrtimer tasklet with softirq hrtimer

[Anna-Maria Gleixner]

[-- Attachment #1: xfrm_Replace_hrtimer_tasklet_with_softirq_hrtimer.patch --]
[-- Type: text/plain, Size: 4776 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
callback in softirq context and remove the hrtimer_tasklet.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org

---
 include/net/xfrm.h    |    2 +-
 net/xfrm/xfrm_state.c |   30 ++++++++++++++++++------------
 2 files changed, 19 insertions(+), 13 deletions(-)

--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -216,7 +216,7 @@ struct xfrm_state {
 	struct xfrm_stats	stats;
 
 	struct xfrm_lifetime_cur curlft;
-	struct tasklet_hrtimer	mtimer;
+	struct hrtimer		mtimer;
 
 	struct xfrm_state_offload xso;
 
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -426,7 +426,7 @@ static void xfrm_put_mode(struct xfrm_mo
 
 static void xfrm_state_gc_destroy(struct xfrm_state *x)
 {
-	tasklet_hrtimer_cancel(&x->mtimer);
+	hrtimer_cancel(&x->mtimer);
 	del_timer_sync(&x->rtimer);
 	kfree(x->aead);
 	kfree(x->aalg);
@@ -471,8 +471,8 @@ static void xfrm_state_gc_task(struct wo
 
 static enum hrtimer_restart xfrm_timer_handler(struct hrtimer *me)
 {
-	struct tasklet_hrtimer *thr = container_of(me, struct tasklet_hrtimer, timer);
-	struct xfrm_state *x = container_of(thr, struct xfrm_state, mtimer);
+	struct xfrm_state *x = container_of(me, struct xfrm_state, mtimer);
+	enum hrtimer_restart ret = HRTIMER_NORESTART;
 	unsigned long now = get_seconds();
 	long next = LONG_MAX;
 	int warn = 0;
@@ -536,7 +536,8 @@ static enum hrtimer_restart xfrm_timer_h
 		km_state_expired(x, 0, 0);
 resched:
 	if (next != LONG_MAX) {
-		tasklet_hrtimer_start(&x->mtimer, ktime_set(next, 0), HRTIMER_MODE_REL);
+		hrtimer_forward_now(&x->mtimer, ktime_set(next, 0));
+		ret = HRTIMER_RESTART;
 	}
 
 	goto out;
@@ -553,7 +554,7 @@ static enum hrtimer_restart xfrm_timer_h
 
 out:
 	spin_unlock(&x->lock);
-	return HRTIMER_NORESTART;
+	return ret;
 }
 
 static void xfrm_replay_timer_handler(unsigned long data);
@@ -572,8 +573,8 @@ struct xfrm_state *xfrm_state_alloc(stru
 		INIT_HLIST_NODE(&x->bydst);
 		INIT_HLIST_NODE(&x->bysrc);
 		INIT_HLIST_NODE(&x->byspi);
-		tasklet_hrtimer_init(&x->mtimer, xfrm_timer_handler,
-					CLOCK_BOOTTIME, HRTIMER_MODE_ABS);
+		hrtimer_init(&x->mtimer, CLOCK_BOOTTIME, HRTIMER_MODE_ABS_SOFT);
+		x->mtimer.function = xfrm_timer_handler;
 		setup_timer(&x->rtimer, xfrm_replay_timer_handler,
 				(unsigned long)x);
 		x->curlft.add_time = get_seconds();
@@ -1030,7 +1031,9 @@ xfrm_state_find(const xfrm_address_t *da
 				hlist_add_head_rcu(&x->byspi, net->xfrm.state_byspi + h);
 			}
 			x->lft.hard_add_expires_seconds = net->xfrm.sysctl_acq_expires;
-			tasklet_hrtimer_start(&x->mtimer, ktime_set(net->xfrm.sysctl_acq_expires, 0), HRTIMER_MODE_REL);
+			hrtimer_start(&x->mtimer,
+				      ktime_set(net->xfrm.sysctl_acq_expires, 0),
+				      HRTIMER_MODE_REL_SOFT);
 			net->xfrm.state_num++;
 			xfrm_hash_grow_check(net, x->bydst.next != NULL);
 			spin_unlock_bh(&net->xfrm.xfrm_state_lock);
@@ -1141,7 +1144,7 @@ static void __xfrm_state_insert(struct x
 		hlist_add_head_rcu(&x->byspi, net->xfrm.state_byspi + h);
 	}
 
-	tasklet_hrtimer_start(&x->mtimer, ktime_set(1, 0), HRTIMER_MODE_REL);
+	hrtimer_start(&x->mtimer, ktime_set(1, 0), HRTIMER_MODE_REL_SOFT);
 	if (x->replay_maxage)
 		mod_timer(&x->rtimer, jiffies + x->replay_maxage);
 
@@ -1245,7 +1248,9 @@ static struct xfrm_state *__find_acq_cor
 		x->mark.m = m->m;
 		x->lft.hard_add_expires_seconds = net->xfrm.sysctl_acq_expires;
 		xfrm_state_hold(x);
-		tasklet_hrtimer_start(&x->mtimer, ktime_set(net->xfrm.sysctl_acq_expires, 0), HRTIMER_MODE_REL);
+		hrtimer_start(&x->mtimer,
+			      ktime_set(net->xfrm.sysctl_acq_expires, 0),
+			      HRTIMER_MODE_REL_SOFT);
 		list_add(&x->km.all, &net->xfrm.state_all);
 		hlist_add_head_rcu(&x->bydst, net->xfrm.state_bydst + h);
 		h = xfrm_src_hash(net, daddr, saddr, family);
@@ -1544,7 +1549,8 @@ int xfrm_state_update(struct xfrm_state
 		memcpy(&x1->lft, &x->lft, sizeof(x1->lft));
 		x1->km.dying = 0;
 
-		tasklet_hrtimer_start(&x1->mtimer, ktime_set(1, 0), HRTIMER_MODE_REL);
+		hrtimer_start(&x1->mtimer, ktime_set(1, 0),
+			      HRTIMER_MODE_REL_SOFT);
 		if (x1->curlft.use_time)
 			xfrm_state_check_expire(x1);
 
@@ -1568,7 +1574,7 @@ int xfrm_state_check_expire(struct xfrm_
 	if (x->curlft.bytes >= x->lft.hard_byte_limit ||
 	    x->curlft.packets >= x->lft.hard_packet_limit) {
 		x->km.state = XFRM_STATE_EXPIRED;
-		tasklet_hrtimer_start(&x->mtimer, 0, HRTIMER_MODE_REL);
+		hrtimer_start(&x->mtimer, 0, HRTIMER_MODE_REL_SOFT);
 		return -EINVAL;
 	}
 

[PATCH v2 33/37] softirq: Remove tasklet_hrtimer

[Anna-Maria Gleixner]

[-- Attachment #1: softirq_Remove_tasklet_hrtimer.patch --]
[-- Type: text/plain, Size: 3179 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

There are no more tasklet_hrtimer users of this interface.
Remove it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 include/linux/interrupt.h |   25 ----------------------
 kernel/softirq.c          |   51 ----------------------------------------------
 2 files changed, 76 deletions(-)

--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -632,31 +632,6 @@ extern void tasklet_kill_immediate(struc
 extern void tasklet_init(struct tasklet_struct *t,
 			 void (*func)(unsigned long), unsigned long data);
 
-struct tasklet_hrtimer {
-	struct hrtimer		timer;
-	struct tasklet_struct	tasklet;
-	enum hrtimer_restart	(*function)(struct hrtimer *);
-};
-
-extern void
-tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
-		     enum hrtimer_restart (*function)(struct hrtimer *),
-		     clockid_t which_clock, enum hrtimer_mode mode);
-
-static inline
-void tasklet_hrtimer_start(struct tasklet_hrtimer *ttimer, ktime_t time,
-			   const enum hrtimer_mode mode)
-{
-	hrtimer_start(&ttimer->timer, time, mode);
-}
-
-static inline
-void tasklet_hrtimer_cancel(struct tasklet_hrtimer *ttimer)
-{
-	hrtimer_cancel(&ttimer->timer);
-	tasklet_kill(&ttimer->tasklet);
-}
-
 /*
  * Autoprobing for irqs:
  *
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -594,57 +594,6 @@ void tasklet_kill(struct tasklet_struct
 }
 EXPORT_SYMBOL(tasklet_kill);
 
-/*
- * tasklet_hrtimer
- */
-
-/*
- * The trampoline is called when the hrtimer expires. It schedules a tasklet
- * to run __tasklet_hrtimer_trampoline() which in turn will call the intended
- * hrtimer callback, but from softirq context.
- */
-static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer)
-{
-	struct tasklet_hrtimer *ttimer =
-		container_of(timer, struct tasklet_hrtimer, timer);
-
-	tasklet_hi_schedule(&ttimer->tasklet);
-	return HRTIMER_NORESTART;
-}
-
-/*
- * Helper function which calls the hrtimer callback from
- * tasklet/softirq context
- */
-static void __tasklet_hrtimer_trampoline(unsigned long data)
-{
-	struct tasklet_hrtimer *ttimer = (void *)data;
-	enum hrtimer_restart restart;
-
-	restart = ttimer->function(&ttimer->timer);
-	if (restart != HRTIMER_NORESTART)
-		hrtimer_restart(&ttimer->timer);
-}
-
-/**
- * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks
- * @ttimer:	 tasklet_hrtimer which is initialized
- * @function:	 hrtimer callback function which gets called from softirq context
- * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME)
- * @mode:	 hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL)
- */
-void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
-			  enum hrtimer_restart (*function)(struct hrtimer *),
-			  clockid_t which_clock, enum hrtimer_mode mode)
-{
-	hrtimer_init(&ttimer->timer, which_clock, mode);
-	ttimer->timer.function = __hrtimer_tasklet_trampoline;
-	tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline,
-		     (unsigned long)ttimer);
-	ttimer->function = function;
-}
-EXPORT_SYMBOL_GPL(tasklet_hrtimer_init);
-
 void __init softirq_init(void)
 {
 	int cpu;

[PATCH v2 34/37] ALSA/dummy: Replace tasklet with softirq hrtimer

[Anna-Maria Gleixner]

[-- Attachment #1: ALSAdummy_Replace_tasklet_with_softirq_hrtimer.patch --]
[-- Type: text/plain, Size: 4008 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

The tasklet is used to defer the execution of snd_pcm_period_elapsed() to
the softirq context. Using the HRTIMER_MODE_SOFT mode invokes the timer
callback in softirq context as well which renders the tasklet useless.

[o-takashi: avoid stall due to a call of hrtimer_cancel() on a callback
            of hrtimer]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: alsa-devel@alsa-project.org
Link: http://lkml.kernel.org/r/20170905161820.jtysvxtfleunbbmf@breakpoint.cc

---
On 2017-09-06 01:05:43 [+0900], Takashi Sakamoto wrote:
> As Iwai-san mentioned, in this function, .trigger can be called in two
> cases; XRUN occurs and draining is done. Thus, let you change the comment as
> 'In cases of XRUN and draining, this calls .trigger to stop PCM substream.'.
> I'm sorry to trouble you.
> 
> snd_pcm_period_elapsed()
> ->snd_pcm_update_hw_ptr0()
>   ->snd_pcm_update_state()
>     ->snd_pcm_drain_done()
>       ...
>       ->.trigger(TRIGGER_STOP)
>     ->xrun()
>       ->snd_pcm_stop()
>         ...
>         ->.trigger(TRIGGER_STOP)
> 

I think you asked me just to update the comment. Did I do it right?

v2...v3: updated the comment as per Takashi Sakamoto's suggestion.
v1...v2: merged Takashi Sakamoto fixup of the original patch into v2.

 sound/drivers/dummy.c |   27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

--- a/sound/drivers/dummy.c
+++ b/sound/drivers/dummy.c
@@ -376,17 +376,9 @@ struct dummy_hrtimer_pcm {
 	ktime_t period_time;
 	atomic_t running;
 	struct hrtimer timer;
-	struct tasklet_struct tasklet;
 	struct snd_pcm_substream *substream;
 };
 
-static void dummy_hrtimer_pcm_elapsed(unsigned long priv)
-{
-	struct dummy_hrtimer_pcm *dpcm = (struct dummy_hrtimer_pcm *)priv;
-	if (atomic_read(&dpcm->running))
-		snd_pcm_period_elapsed(dpcm->substream);
-}
-
 static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
 {
 	struct dummy_hrtimer_pcm *dpcm;
@@ -394,7 +386,14 @@ static enum hrtimer_restart dummy_hrtime
 	dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer);
 	if (!atomic_read(&dpcm->running))
 		return HRTIMER_NORESTART;
-	tasklet_schedule(&dpcm->tasklet);
+	/*
+	 * In cases of XRUN and draining, this calls .trigger to stop PCM
+	 * substream.
+	 */
+	snd_pcm_period_elapsed(dpcm->substream);
+	if (!atomic_read(&dpcm->running))
+		return HRTIMER_NORESTART;
+
 	hrtimer_forward_now(timer, dpcm->period_time);
 	return HRTIMER_RESTART;
 }
@@ -404,7 +403,7 @@ static int dummy_hrtimer_start(struct sn
 	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
 
 	dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
-	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL);
+	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL_SOFT);
 	atomic_set(&dpcm->running, 1);
 	return 0;
 }
@@ -414,14 +413,14 @@ static int dummy_hrtimer_stop(struct snd
 	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
 
 	atomic_set(&dpcm->running, 0);
-	hrtimer_cancel(&dpcm->timer);
+	if (!hrtimer_callback_running(&dpcm->timer))
+		hrtimer_cancel(&dpcm->timer);
 	return 0;
 }
 
 static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
 {
 	hrtimer_cancel(&dpcm->timer);
-	tasklet_kill(&dpcm->tasklet);
 }
 
 static snd_pcm_uframes_t
@@ -466,12 +465,10 @@ static int dummy_hrtimer_create(struct s
 	if (!dpcm)
 		return -ENOMEM;
 	substream->runtime->private_data = dpcm;
-	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
 	dpcm->timer.function = dummy_hrtimer_callback;
 	dpcm->substream = substream;
 	atomic_set(&dpcm->running, 0);
-	tasklet_init(&dpcm->tasklet, dummy_hrtimer_pcm_elapsed,
-		     (unsigned long)dpcm);
 	return 0;
 }
 

[PATCH v2 34/37] ALSA/dummy: Replace tasklet with softirq hrtimer

[Anna-Maria Gleixner]

[-- Attachment #1: ALSAdummy_Replace_tasklet_with_softirq_hrtimer.patch --]
[-- Type: text/plain, Size: 4008 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

The tasklet is used to defer the execution of snd_pcm_period_elapsed() to
the softirq context. Using the HRTIMER_MODE_SOFT mode invokes the timer
callback in softirq context as well which renders the tasklet useless.

[o-takashi: avoid stall due to a call of hrtimer_cancel() on a callback
            of hrtimer]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: alsa-devel@alsa-project.org
Link: http://lkml.kernel.org/r/20170905161820.jtysvxtfleunbbmf@breakpoint.cc

---
On 2017-09-06 01:05:43 [+0900], Takashi Sakamoto wrote:
> As Iwai-san mentioned, in this function, .trigger can be called in two
> cases; XRUN occurs and draining is done. Thus, let you change the comment as
> 'In cases of XRUN and draining, this calls .trigger to stop PCM substream.'.
> I'm sorry to trouble you.
> 
> snd_pcm_period_elapsed()
> ->snd_pcm_update_hw_ptr0()
>   ->snd_pcm_update_state()
>     ->snd_pcm_drain_done()
>       ...
>       ->.trigger(TRIGGER_STOP)
>     ->xrun()
>       ->snd_pcm_stop()
>         ...
>         ->.trigger(TRIGGER_STOP)
> 

I think you asked me just to update the comment. Did I do it right?

v2...v3: updated the comment as per Takashi Sakamoto's suggestion.
v1...v2: merged Takashi Sakamoto fixup of the original patch into v2.

 sound/drivers/dummy.c |   27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

--- a/sound/drivers/dummy.c
+++ b/sound/drivers/dummy.c
@@ -376,17 +376,9 @@ struct dummy_hrtimer_pcm {
 	ktime_t period_time;
 	atomic_t running;
 	struct hrtimer timer;
-	struct tasklet_struct tasklet;
 	struct snd_pcm_substream *substream;
 };
 
-static void dummy_hrtimer_pcm_elapsed(unsigned long priv)
-{
-	struct dummy_hrtimer_pcm *dpcm = (struct dummy_hrtimer_pcm *)priv;
-	if (atomic_read(&dpcm->running))
-		snd_pcm_period_elapsed(dpcm->substream);
-}
-
 static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
 {
 	struct dummy_hrtimer_pcm *dpcm;
@@ -394,7 +386,14 @@ static enum hrtimer_restart dummy_hrtime
 	dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer);
 	if (!atomic_read(&dpcm->running))
 		return HRTIMER_NORESTART;
-	tasklet_schedule(&dpcm->tasklet);
+	/*
+	 * In cases of XRUN and draining, this calls .trigger to stop PCM
+	 * substream.
+	 */
+	snd_pcm_period_elapsed(dpcm->substream);
+	if (!atomic_read(&dpcm->running))
+		return HRTIMER_NORESTART;
+
 	hrtimer_forward_now(timer, dpcm->period_time);
 	return HRTIMER_RESTART;
 }
@@ -404,7 +403,7 @@ static int dummy_hrtimer_start(struct sn
 	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
 
 	dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
-	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL);
+	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL_SOFT);
 	atomic_set(&dpcm->running, 1);
 	return 0;
 }
@@ -414,14 +413,14 @@ static int dummy_hrtimer_stop(struct snd
 	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
 
 	atomic_set(&dpcm->running, 0);
-	hrtimer_cancel(&dpcm->timer);
+	if (!hrtimer_callback_running(&dpcm->timer))
+		hrtimer_cancel(&dpcm->timer);
 	return 0;
 }
 
 static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
 {
 	hrtimer_cancel(&dpcm->timer);
-	tasklet_kill(&dpcm->tasklet);
 }
 
 static snd_pcm_uframes_t
@@ -466,12 +465,10 @@ static int dummy_hrtimer_create(struct s
 	if (!dpcm)
 		return -ENOMEM;
 	substream->runtime->private_data = dpcm;
-	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
 	dpcm->timer.function = dummy_hrtimer_callback;
 	dpcm->substream = substream;
 	atomic_set(&dpcm->running, 0);
-	tasklet_init(&dpcm->tasklet, dummy_hrtimer_pcm_elapsed,
-		     (unsigned long)dpcm);
 	return 0;
 }
 

[PATCH v2 36/37] usb/gadget/NCM: Replace tasklet with softirq hrtimer

[Anna-Maria Gleixner]

[-- Attachment #1: usbgadgetNCM_Replace_tasklet_with_softirq_hrtimer.patch --]
[-- Type: text/plain, Size: 2945 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

The tx_tasklet tasklet is used in invoke the hrtimer (task_timer) in
softirq context. This can be also achieved without the tasklet but
with HRTIMER_MODE_SOFT as hrtimer mode.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: linux-usb@vger.kernel.org
---
 drivers/usb/gadget/function/f_ncm.c |   30 +++++++-----------------------
 1 file changed, 7 insertions(+), 23 deletions(-)

--- a/drivers/usb/gadget/function/f_ncm.c
+++ b/drivers/usb/gadget/function/f_ncm.c
@@ -77,9 +77,7 @@ struct f_ncm {
 	struct sk_buff			*skb_tx_ndp;
 	u16				ndp_dgram_count;
 	bool				timer_force_tx;
-	struct tasklet_struct		tx_tasklet;
 	struct hrtimer			task_timer;
-
 	bool				timer_stopping;
 };
 
@@ -1108,7 +1106,7 @@ static struct sk_buff *ncm_wrap_ntb(stru
 
 		/* Delay the timer. */
 		hrtimer_start(&ncm->task_timer, TX_TIMEOUT_NSECS,
-			      HRTIMER_MODE_REL);
+			      HRTIMER_MODE_REL_SOFT);
 
 		/* Add the datagram position entries */
 		ntb_ndp = skb_put_zero(ncm->skb_tx_ndp, dgram_idx_len);
@@ -1152,17 +1150,15 @@ static struct sk_buff *ncm_wrap_ntb(stru
 }
 
 /*
- * This transmits the NTB if there are frames waiting.
+ * The transmit should only be run if no skb data has been sent
+ * for a certain duration.
  */
-static void ncm_tx_tasklet(unsigned long data)
+static enum hrtimer_restart ncm_tx_timeout(struct hrtimer *data)
 {
-	struct f_ncm	*ncm = (void *)data;
-
-	if (ncm->timer_stopping)
-		return;
+	struct f_ncm *ncm = container_of(data, struct f_ncm, task_timer);
 
 	/* Only send if data is available. */
-	if (ncm->skb_tx_data) {
+	if (!ncm->timer_stopping && ncm->skb_tx_data) {
 		ncm->timer_force_tx = true;
 
 		/* XXX This allowance of a NULL skb argument to ndo_start_xmit
@@ -1175,16 +1171,6 @@ static void ncm_tx_tasklet(unsigned long
 
 		ncm->timer_force_tx = false;
 	}
-}
-
-/*
- * The transmit should only be run if no skb data has been sent
- * for a certain duration.
- */
-static enum hrtimer_restart ncm_tx_timeout(struct hrtimer *data)
-{
-	struct f_ncm *ncm = container_of(data, struct f_ncm, task_timer);
-	tasklet_schedule(&ncm->tx_tasklet);
 	return HRTIMER_NORESTART;
 }
 
@@ -1517,8 +1503,7 @@ static int ncm_bind(struct usb_configura
 	ncm->port.open = ncm_open;
 	ncm->port.close = ncm_close;
 
-	tasklet_init(&ncm->tx_tasklet, ncm_tx_tasklet, (unsigned long) ncm);
-	hrtimer_init(&ncm->task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer_init(&ncm->task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
 	ncm->task_timer.function = ncm_tx_timeout;
 
 	DBG(cdev, "CDC Network: %s speed IN/%s OUT/%s NOTIFY/%s\n",
@@ -1627,7 +1612,6 @@ static void ncm_unbind(struct usb_config
 	DBG(c->cdev, "ncm unbind\n");
 
 	hrtimer_cancel(&ncm->task_timer);
-	tasklet_kill(&ncm->tx_tasklet);
 
 	ncm_string_defs[0].id = 0;
 	usb_free_all_descriptors(f);

[PATCH v2 37/37] net/mvpp2: Replace tasklet with softirq hrtimer

[Anna-Maria Gleixner]

[-- Attachment #1: netmvpp2_Replace_tasklet_with_softirq_hrtimer.patch --]
[-- Type: text/plain, Size: 3918 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

The tx_done_tasklet tasklet is used in invoke the hrtimer
(mvpp2_hr_timer_cb) in softirq context. This can be also achieved without
the tasklet but with HRTIMER_MODE_SOFT as hrtimer mode.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: netdev@vger.kernel.org
---
 drivers/net/ethernet/marvell/mvpp2.c |   62 ++++++++++++++---------------------
 1 file changed, 25 insertions(+), 37 deletions(-)

--- a/drivers/net/ethernet/marvell/mvpp2.c
+++ b/drivers/net/ethernet/marvell/mvpp2.c
@@ -830,9 +830,8 @@ struct mvpp2_pcpu_stats {
 /* Per-CPU port control */
 struct mvpp2_port_pcpu {
 	struct hrtimer tx_done_timer;
+	struct net_device *dev;
 	bool timer_scheduled;
-	/* Tasklet for egress finalization */
-	struct tasklet_struct tx_done_tasklet;
 };
 
 struct mvpp2_queue_vector {
@@ -5973,46 +5972,34 @@ static void mvpp2_link_event(struct net_
 	}
 }
 
-static void mvpp2_timer_set(struct mvpp2_port_pcpu *port_pcpu)
-{
-	ktime_t interval;
-
-	if (!port_pcpu->timer_scheduled) {
-		port_pcpu->timer_scheduled = true;
-		interval = MVPP2_TXDONE_HRTIMER_PERIOD_NS;
-		hrtimer_start(&port_pcpu->tx_done_timer, interval,
-			      HRTIMER_MODE_REL_PINNED);
-	}
-}
-
-static void mvpp2_tx_proc_cb(unsigned long data)
+static enum hrtimer_restart mvpp2_hr_timer_cb(struct hrtimer *timer)
 {
-	struct net_device *dev = (struct net_device *)data;
-	struct mvpp2_port *port = netdev_priv(dev);
-	struct mvpp2_port_pcpu *port_pcpu = this_cpu_ptr(port->pcpu);
+	struct net_device *dev;
+	struct mvpp2_port *port;
+	struct mvpp2_port_pcpu *port_pcpu;
 	unsigned int tx_todo, cause;
 
+	port_pcpu = container_of(timer, struct mvpp2_port_pcpu, tx_done_timer);
+	dev = port_pcpu->dev;
+
 	if (!netif_running(dev))
-		return;
+		return HRTIMER_NORESTART;
+
 	port_pcpu->timer_scheduled = false;
+	port = netdev_priv(dev);
 
 	/* Process all the Tx queues */
 	cause = (1 << port->ntxqs) - 1;
 	tx_todo = mvpp2_tx_done(port, cause, smp_processor_id());
 
 	/* Set the timer in case not all the packets were processed */
-	if (tx_todo)
-		mvpp2_timer_set(port_pcpu);
-}
-
-static enum hrtimer_restart mvpp2_hr_timer_cb(struct hrtimer *timer)
-{
-	struct mvpp2_port_pcpu *port_pcpu = container_of(timer,
-							 struct mvpp2_port_pcpu,
-							 tx_done_timer);
-
-	tasklet_schedule(&port_pcpu->tx_done_tasklet);
+	if (tx_todo && !port_pcpu->timer_scheduled) {
+		port_pcpu->timer_scheduled = true;
+		hrtimer_forward_now(&port_pcpu->tx_done_timer,
+				    MVPP2_TXDONE_HRTIMER_PERIOD_NS);
 
+		return HRTIMER_RESTART;
+	}
 	return HRTIMER_NORESTART;
 }
 
@@ -6498,7 +6485,12 @@ static int mvpp2_tx(struct sk_buff *skb,
 	    txq_pcpu->count > 0) {
 		struct mvpp2_port_pcpu *port_pcpu = this_cpu_ptr(port->pcpu);
 
-		mvpp2_timer_set(port_pcpu);
+		if (!port_pcpu->timer_scheduled) {
+			port_pcpu->timer_scheduled = true;
+			hrtimer_start(&port_pcpu->tx_done_timer,
+				      MVPP2_TXDONE_HRTIMER_PERIOD_NS,
+				      HRTIMER_MODE_REL_PINNED_SOFT);
+		}
 	}
 
 	return NETDEV_TX_OK;
@@ -6883,7 +6875,6 @@ static int mvpp2_stop(struct net_device
 
 			hrtimer_cancel(&port_pcpu->tx_done_timer);
 			port_pcpu->timer_scheduled = false;
-			tasklet_kill(&port_pcpu->tx_done_tasklet);
 		}
 	}
 	mvpp2_cleanup_rxqs(port);
@@ -7651,13 +7642,10 @@ static int mvpp2_port_probe(struct platf
 			port_pcpu = per_cpu_ptr(port->pcpu, cpu);
 
 			hrtimer_init(&port_pcpu->tx_done_timer, CLOCK_MONOTONIC,
-				     HRTIMER_MODE_REL_PINNED);
+				     HRTIMER_MODE_REL_PINNED_SOFT);
 			port_pcpu->tx_done_timer.function = mvpp2_hr_timer_cb;
 			port_pcpu->timer_scheduled = false;
-
-			tasklet_init(&port_pcpu->tx_done_tasklet,
-				     mvpp2_tx_proc_cb,
-				     (unsigned long)dev);
+			port_pcpu->dev = dev;
 		}
 	}
 

Re: [PATCH v2 31/37] mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer

[Johannes Berg]

On Sun, 2017-10-22 at 23:40 +0200, Anna-Maria Gleixner wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
> callback in softirq context and remove the hrtimer_tasklet.

This doesn't build on my tree, due to HRTIMER_MODE_REL_SOFT not
existing. Neither does HRTIMER_MODE_SOFT mentioned above, but that's
just a commit log mistake.

(It also didn't apply on my tree, but that was a trivial context
change.)

I don't understand why you initialize it with HRTIMER_MODE_ABS_SOFT
either though:

> +       hrtimer_init(&data->beacon_timer, CLOCK_MONOTONIC,
> +                    HRTIMER_MODE_ABS_SOFT);

shouldn't that already be REL?

johannes

Re: [PATCH v2 31/37] mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer

[Thomas Gleixner]

On Mon, 23 Oct 2017, Johannes Berg wrote:

> On Sun, 2017-10-22 at 23:40 +0200, Anna-Maria Gleixner wrote:
> > From: Thomas Gleixner <tglx@linutronix.de>
> > 
> > Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
> > callback in softirq context and remove the hrtimer_tasklet.

I can't build as its part of the whole hrtimer rework series.

> This doesn't build on my tree, due to HRTIMER_MODE_REL_SOFT not
> existing. Neither does HRTIMER_MODE_SOFT mentioned above, but that's
> just a commit log mistake.

Oops.

> (It also didn't apply on my tree, but that was a trivial context
> change.)
> 
> I don't understand why you initialize it with HRTIMER_MODE_ABS_SOFT
> either though:
> 
> > +       hrtimer_init(&data->beacon_timer, CLOCK_MONOTONIC,
> > +                    HRTIMER_MODE_ABS_SOFT);

Sure, though it does not matter in that case. Will fix that up.

Thanks,

	tglx

Re: [PATCH v2 31/37] mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer

[Johannes Berg]

On Mon, 2017-10-23 at 12:23 +0200, Thomas Gleixner wrote:
> On Mon, 23 Oct 2017, Johannes Berg wrote:
> 
> > On Sun, 2017-10-22 at 23:40 +0200, Anna-Maria Gleixner wrote:
> > > From: Thomas Gleixner <tglx@linutronix.de>
> > > 
> > > Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
> > > callback in softirq context and remove the hrtimer_tasklet.
> 
> I can't build as its part of the whole hrtimer rework series.

I guess you mean you *can* build it? Surely you're introducing the new
HR timer modes in some patch that I didn't see? :-)

> > > +       hrtimer_init(&data->beacon_timer, CLOCK_MONOTONIC,
> > > +                    HRTIMER_MODE_ABS_SOFT);
> 
> Sure, though it does not matter in that case. Will fix that up.

Right. Then again, why even pass it to init() and start()? Can you
start without going through start()?

johannes

Re: [PATCH v2 31/37] mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer

[Thomas Gleixner]

On Mon, 23 Oct 2017, Johannes Berg wrote:
> On Mon, 2017-10-23 at 12:23 +0200, Thomas Gleixner wrote:
> > On Mon, 23 Oct 2017, Johannes Berg wrote:
> > 
> > > On Sun, 2017-10-22 at 23:40 +0200, Anna-Maria Gleixner wrote:
> > > > From: Thomas Gleixner <tglx@linutronix.de>
> > > > 
> > > > Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
> > > > callback in softirq context and remove the hrtimer_tasklet.
> > 
> > I can't build as its part of the whole hrtimer rework series.
> 
> I guess you mean you *can* build it? Surely you're introducing the new
> HR timer modes in some patch that I didn't see? :-)

Sorry, we did not want to expose you to 30 patches fiddling with the core
code. They are on LKML though.

> > > > +       hrtimer_init(&data->beacon_timer, CLOCK_MONOTONIC,
> > > > +                    HRTIMER_MODE_ABS_SOFT);
> > 
> > Sure, though it does not matter in that case. Will fix that up.
> 
> Right. Then again, why even pass it to init() and start()? Can you
> start without going through start()?

There is a subtle magic with CLOCK_REALTIME timers.

CLOCK_REALTIME timers differentiate between ABS and REL modes. ABS timers
are exposed to clock modifications (settimeofday() ...), REL timers are
not. We solve that by associating them to different clock bases, which has
to be done at init time, but the start function needs the REL/ABS
information as well.

For CLOCK_MONOTONIC this is not really required, but the function is used
for all clock bases, so we require the mode bits for all.

Thanks,

	tglx

Re: [PATCH v2 31/37] mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer

[Johannes Berg]

> > I guess you mean you *can* build it? Surely you're introducing the new
> > HR timer modes in some patch that I didn't see? :-)
> 
> Sorry, we did not want to expose you to 30 patches fiddling with the core
> code. They are on LKML though.

Sure, no worries. I just didn't even realize I shouldn't be applying
the patch (myself) :-)

> > Right. Then again, why even pass it to init() and start()? Can you
> > start without going through start()?
> 
> There is a subtle magic with CLOCK_REALTIME timers.
> 
> CLOCK_REALTIME timers differentiate between ABS and REL modes. ABS timers
> are exposed to clock modifications (settimeofday() ...), REL timers are
> not. We solve that by associating them to different clock bases, which has
> to be done at init time, but the start function needs the REL/ABS
> information as well.
> 
> For CLOCK_MONOTONIC this is not really required, but the function is used
> for all clock bases, so we require the mode bits for all.

Hmm. Couldn't you just store that then from init to use in start?

If you don't store it, yet don't verify that you passed the same 
thing, do you at least check that it's compatible? Sounds like
something will totally go wrong if I pass CLOCK_REALTIME/ABS first and
then use REL for start, or vice versa?

Also, in the code I see only checking

if (mode != HRTIMER_MODE_ABS) {
	// change clock ID:
	// realtime -> monotonic
	// realtime_soft -> monotonic_soft
}

but you're passing HRTIMER_MODE_ABS_SOFT too, isn't that considered an
ABS mode?

But then, looking at the code again, I don't even see
HRTIMER_MODE_ABS_SOFT existing, it sounds like it should be

hrtimer_init(..., CLOCK_REALTIME_SOFT, HRTIMER_MODE_REL);

then?

At least then the code I mentioned above makes sense, but it still
feels pretty dangerous to not just store the mode and use it in start,
but to require passing it again. You even just introduced the same bug,
it just happened to not matter in this case since the clock isn't
realtime.

Or am I completely confused now?

johannes

Re: [PATCH v2 00/37] hrtimer: Provide softirq context hrtimers

[Peter Zijlstra]

On Sun, Oct 22, 2017 at 11:39:38PM +0200, Anna-Maria Gleixner wrote:
> This series implements a new approach by adding SOFT hrtimer mode and
> instead of doing the list shuffle, timers started with this mode are put
> into separate soft expiry hrtimer queues. These queues are evaluated only
> when the hardirq context detects that the first expiring timer in the
> softirq queues has expired. That makes the overhead in the hardirq context
> minimal.

Thanks!

1-29,33: Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Re: [PATCH v2 34/37] ALSA/dummy: Replace tasklet with softirq hrtimer

[Takashi Iwai]

On Sun, 22 Oct 2017 23:40:12 +0200,
Anna-Maria Gleixner wrote:
> 
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> The tasklet is used to defer the execution of snd_pcm_period_elapsed() to
> the softirq context. Using the HRTIMER_MODE_SOFT mode invokes the timer
> callback in softirq context as well which renders the tasklet useless.
> 
> [o-takashi: avoid stall due to a call of hrtimer_cancel() on a callback
>             of hrtimer]
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> Cc: Jaroslav Kysela <perex@perex.cz>
> Cc: Takashi Iwai <tiwai@suse.com>

Feel free to take my ack:
  Reviewed-by: Takashi Iwai <tiwai@suse.de>


thanks,

Takashi

> Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp>
> Cc: alsa-devel@alsa-project.org
> Link: http://lkml.kernel.org/r/20170905161820.jtysvxtfleunbbmf@breakpoint.cc
> 
> ---
> On 2017-09-06 01:05:43 [+0900], Takashi Sakamoto wrote:
> > As Iwai-san mentioned, in this function, .trigger can be called in two
> > cases; XRUN occurs and draining is done. Thus, let you change the comment as
> > 'In cases of XRUN and draining, this calls .trigger to stop PCM substream.'.
> > I'm sorry to trouble you.
> > 
> > snd_pcm_period_elapsed()
> > ->snd_pcm_update_hw_ptr0()
> >   ->snd_pcm_update_state()
> >     ->snd_pcm_drain_done()
> >       ...
> >       ->.trigger(TRIGGER_STOP)
> >     ->xrun()
> >       ->snd_pcm_stop()
> >         ...
> >         ->.trigger(TRIGGER_STOP)
> > 
> 
> I think you asked me just to update the comment. Did I do it right?
> 
> v2...v3: updated the comment as per Takashi Sakamoto's suggestion.
> v1...v2: merged Takashi Sakamoto fixup of the original patch into v2.
> 
>  sound/drivers/dummy.c |   27 ++++++++++++---------------
>  1 file changed, 12 insertions(+), 15 deletions(-)
> 
> --- a/sound/drivers/dummy.c
> +++ b/sound/drivers/dummy.c
> @@ -376,17 +376,9 @@ struct dummy_hrtimer_pcm {
>  	ktime_t period_time;
>  	atomic_t running;
>  	struct hrtimer timer;
> -	struct tasklet_struct tasklet;
>  	struct snd_pcm_substream *substream;
>  };
>  
> -static void dummy_hrtimer_pcm_elapsed(unsigned long priv)
> -{
> -	struct dummy_hrtimer_pcm *dpcm = (struct dummy_hrtimer_pcm *)priv;
> -	if (atomic_read(&dpcm->running))
> -		snd_pcm_period_elapsed(dpcm->substream);
> -}
> -
>  static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
>  {
>  	struct dummy_hrtimer_pcm *dpcm;
> @@ -394,7 +386,14 @@ static enum hrtimer_restart dummy_hrtime
>  	dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer);
>  	if (!atomic_read(&dpcm->running))
>  		return HRTIMER_NORESTART;
> -	tasklet_schedule(&dpcm->tasklet);
> +	/*
> +	 * In cases of XRUN and draining, this calls .trigger to stop PCM
> +	 * substream.
> +	 */
> +	snd_pcm_period_elapsed(dpcm->substream);
> +	if (!atomic_read(&dpcm->running))
> +		return HRTIMER_NORESTART;
> +
>  	hrtimer_forward_now(timer, dpcm->period_time);
>  	return HRTIMER_RESTART;
>  }
> @@ -404,7 +403,7 @@ static int dummy_hrtimer_start(struct sn
>  	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
>  
>  	dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
> -	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL);
> +	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL_SOFT);
>  	atomic_set(&dpcm->running, 1);
>  	return 0;
>  }
> @@ -414,14 +413,14 @@ static int dummy_hrtimer_stop(struct snd
>  	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
>  
>  	atomic_set(&dpcm->running, 0);
> -	hrtimer_cancel(&dpcm->timer);
> +	if (!hrtimer_callback_running(&dpcm->timer))
> +		hrtimer_cancel(&dpcm->timer);
>  	return 0;
>  }
>  
>  static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
>  {
>  	hrtimer_cancel(&dpcm->timer);
> -	tasklet_kill(&dpcm->tasklet);
>  }
>  
>  static snd_pcm_uframes_t
> @@ -466,12 +465,10 @@ static int dummy_hrtimer_create(struct s
>  	if (!dpcm)
>  		return -ENOMEM;
>  	substream->runtime->private_data = dpcm;
> -	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> +	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
>  	dpcm->timer.function = dummy_hrtimer_callback;
>  	dpcm->substream = substream;
>  	atomic_set(&dpcm->running, 0);
> -	tasklet_init(&dpcm->tasklet, dummy_hrtimer_pcm_elapsed,
> -		     (unsigned long)dpcm);
>  	return 0;
>  }
>  
> 
> 
> 

Re: [PATCH v2 34/37] ALSA/dummy: Replace tasklet with softirq hrtimer

[Takashi Iwai]

On Sun, 22 Oct 2017 23:40:12 +0200,
Anna-Maria Gleixner wrote:
> 
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> The tasklet is used to defer the execution of snd_pcm_period_elapsed() to
> the softirq context. Using the HRTIMER_MODE_SOFT mode invokes the timer
> callback in softirq context as well which renders the tasklet useless.
> 
> [o-takashi: avoid stall due to a call of hrtimer_cancel() on a callback
>             of hrtimer]
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> Cc: Jaroslav Kysela <perex@perex.cz>
> Cc: Takashi Iwai <tiwai@suse.com>

Feel free to take my ack:
  Reviewed-by: Takashi Iwai <tiwai@suse.de>


thanks,

Takashi

> Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp>
> Cc: alsa-devel@alsa-project.org
> Link: http://lkml.kernel.org/r/20170905161820.jtysvxtfleunbbmf@breakpoint.cc
> 
> ---
> On 2017-09-06 01:05:43 [+0900], Takashi Sakamoto wrote:
> > As Iwai-san mentioned, in this function, .trigger can be called in two
> > cases; XRUN occurs and draining is done. Thus, let you change the comment as
> > 'In cases of XRUN and draining, this calls .trigger to stop PCM substream.'.
> > I'm sorry to trouble you.
> > 
> > snd_pcm_period_elapsed()
> > ->snd_pcm_update_hw_ptr0()
> >   ->snd_pcm_update_state()
> >     ->snd_pcm_drain_done()
> >       ...
> >       ->.trigger(TRIGGER_STOP)
> >     ->xrun()
> >       ->snd_pcm_stop()
> >         ...
> >         ->.trigger(TRIGGER_STOP)
> > 
> 
> I think you asked me just to update the comment. Did I do it right?
> 
> v2...v3: updated the comment as per Takashi Sakamoto's suggestion.
> v1...v2: merged Takashi Sakamoto fixup of the original patch into v2.
> 
>  sound/drivers/dummy.c |   27 ++++++++++++---------------
>  1 file changed, 12 insertions(+), 15 deletions(-)
> 
> --- a/sound/drivers/dummy.c
> +++ b/sound/drivers/dummy.c
> @@ -376,17 +376,9 @@ struct dummy_hrtimer_pcm {
>  	ktime_t period_time;
>  	atomic_t running;
>  	struct hrtimer timer;
> -	struct tasklet_struct tasklet;
>  	struct snd_pcm_substream *substream;
>  };
>  
> -static void dummy_hrtimer_pcm_elapsed(unsigned long priv)
> -{
> -	struct dummy_hrtimer_pcm *dpcm = (struct dummy_hrtimer_pcm *)priv;
> -	if (atomic_read(&dpcm->running))
> -		snd_pcm_period_elapsed(dpcm->substream);
> -}
> -
>  static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
>  {
>  	struct dummy_hrtimer_pcm *dpcm;
> @@ -394,7 +386,14 @@ static enum hrtimer_restart dummy_hrtime
>  	dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer);
>  	if (!atomic_read(&dpcm->running))
>  		return HRTIMER_NORESTART;
> -	tasklet_schedule(&dpcm->tasklet);
> +	/*
> +	 * In cases of XRUN and draining, this calls .trigger to stop PCM
> +	 * substream.
> +	 */
> +	snd_pcm_period_elapsed(dpcm->substream);
> +	if (!atomic_read(&dpcm->running))
> +		return HRTIMER_NORESTART;
> +
>  	hrtimer_forward_now(timer, dpcm->period_time);
>  	return HRTIMER_RESTART;
>  }
> @@ -404,7 +403,7 @@ static int dummy_hrtimer_start(struct sn
>  	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
>  
>  	dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
> -	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL);
> +	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL_SOFT);
>  	atomic_set(&dpcm->running, 1);
>  	return 0;
>  }
> @@ -414,14 +413,14 @@ static int dummy_hrtimer_stop(struct snd
>  	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
>  
>  	atomic_set(&dpcm->running, 0);
> -	hrtimer_cancel(&dpcm->timer);
> +	if (!hrtimer_callback_running(&dpcm->timer))
> +		hrtimer_cancel(&dpcm->timer);
>  	return 0;
>  }
>  
>  static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
>  {
>  	hrtimer_cancel(&dpcm->timer);
> -	tasklet_kill(&dpcm->tasklet);
>  }
>  
>  static snd_pcm_uframes_t
> @@ -466,12 +465,10 @@ static int dummy_hrtimer_create(struct s
>  	if (!dpcm)
>  		return -ENOMEM;
>  	substream->runtime->private_data = dpcm;
> -	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> +	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
>  	dpcm->timer.function = dummy_hrtimer_callback;
>  	dpcm->substream = substream;
>  	atomic_set(&dpcm->running, 0);
> -	tasklet_init(&dpcm->tasklet, dummy_hrtimer_pcm_elapsed,
> -		     (unsigned long)dpcm);
>  	return 0;
>  }
>  
> 
> 
> 

Re: [PATCH v2 30/37] can/bcm: Replace hrtimer_tasklet with softirq based hrtimer

[Oliver Hartkopp]

On 10/22/2017 11:40 PM, Anna-Maria Gleixner wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
> callback in softirq context and remove the hrtimer_tasklet.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> Cc: Oliver Hartkopp <socketcan@hartkopp.net>

Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>


> Cc: Marc Kleine-Budde <mkl@pengutronix.de>
> Cc: linux-can@vger.kernel.org
> ---
>   net/can/bcm.c |  156 +++++++++++++++++++---------------------------------------
>   1 file changed, 52 insertions(+), 104 deletions(-)
> 
> --- a/net/can/bcm.c
> +++ b/net/can/bcm.c
> @@ -102,7 +102,6 @@ struct bcm_op {
>   	unsigned long frames_abs, frames_filtered;
>   	struct bcm_timeval ival1, ival2;
>   	struct hrtimer timer, thrtimer;
> -	struct tasklet_struct tsklet, thrtsklet;
>   	ktime_t rx_stamp, kt_ival1, kt_ival2, kt_lastmsg;
>   	int rx_ifindex;
>   	int cfsiz;
> @@ -364,25 +363,34 @@ static void bcm_send_to_user(struct bcm_
>   	}
>   }
>   
> -static void bcm_tx_start_timer(struct bcm_op *op)
> +static bool bcm_tx_set_expiry(struct bcm_op *op, struct hrtimer *hrt)
>   {
> +	ktime_t ival;
> +
>   	if (op->kt_ival1 && op->count)
> -		hrtimer_start(&op->timer,
> -			      ktime_add(ktime_get(), op->kt_ival1),
> -			      HRTIMER_MODE_ABS);
> +		ival = op->kt_ival1;
>   	else if (op->kt_ival2)
> -		hrtimer_start(&op->timer,
> -			      ktime_add(ktime_get(), op->kt_ival2),
> -			      HRTIMER_MODE_ABS);
> +		ival = op->kt_ival2;
> +	else
> +		return false;
> +
> +	hrtimer_set_expires(hrt, ktime_add(ktime_get(), ival));
> +	return true;
>   }
>   
> -static void bcm_tx_timeout_tsklet(unsigned long data)
> +static void bcm_tx_start_timer(struct bcm_op *op)
>   {
> -	struct bcm_op *op = (struct bcm_op *)data;
> +	if (bcm_tx_set_expiry(op, &op->timer))
> +		hrtimer_start_expires(&op->timer, HRTIMER_MODE_ABS_SOFT);
> +}
> +
> +/* bcm_tx_timeout_handler - performs cyclic CAN frame transmissions */
> +static enum hrtimer_restart bcm_tx_timeout_handler(struct hrtimer *hrtimer)
> +{
> +	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
>   	struct bcm_msg_head msg_head;
>   
>   	if (op->kt_ival1 && (op->count > 0)) {
> -
>   		op->count--;
>   		if (!op->count && (op->flags & TX_COUNTEVT)) {
>   
> @@ -399,22 +407,12 @@ static void bcm_tx_timeout_tsklet(unsign
>   		}
>   		bcm_can_tx(op);
>   
> -	} else if (op->kt_ival2)
> +	} else if (op->kt_ival2) {
>   		bcm_can_tx(op);
> +	}
>   
> -	bcm_tx_start_timer(op);
> -}
> -
> -/*
> - * bcm_tx_timeout_handler - performs cyclic CAN frame transmissions
> - */
> -static enum hrtimer_restart bcm_tx_timeout_handler(struct hrtimer *hrtimer)
> -{
> -	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
> -
> -	tasklet_schedule(&op->tsklet);
> -
> -	return HRTIMER_NORESTART;
> +	return bcm_tx_set_expiry(op, &op->timer) ?
> +		HRTIMER_RESTART : HRTIMER_NORESTART;
>   }
>   
>   /*
> @@ -480,7 +478,7 @@ static void bcm_rx_update_and_send(struc
>   		/* do not send the saved data - only start throttle timer */
>   		hrtimer_start(&op->thrtimer,
>   			      ktime_add(op->kt_lastmsg, op->kt_ival2),
> -			      HRTIMER_MODE_ABS);
> +			      HRTIMER_MODE_ABS_SOFT);
>   		return;
>   	}
>   
> @@ -539,14 +537,21 @@ static void bcm_rx_starttimer(struct bcm
>   		return;
>   
>   	if (op->kt_ival1)
> -		hrtimer_start(&op->timer, op->kt_ival1, HRTIMER_MODE_REL);
> +		hrtimer_start(&op->timer, op->kt_ival1, HRTIMER_MODE_REL_SOFT);
>   }
>   
> -static void bcm_rx_timeout_tsklet(unsigned long data)
> +/* bcm_rx_timeout_handler - when the (cyclic) CAN frame reception timed out */
> +static enum hrtimer_restart bcm_rx_timeout_handler(struct hrtimer *hrtimer)
>   {
> -	struct bcm_op *op = (struct bcm_op *)data;
> +	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
>   	struct bcm_msg_head msg_head;
>   
> +	/* if user wants to be informed, when cyclic CAN-Messages come back */
> +	if ((op->flags & RX_ANNOUNCE_RESUME) && op->last_frames) {
> +		/* clear received CAN frames to indicate 'nothing received' */
> +		memset(op->last_frames, 0, op->nframes * op->cfsiz);
> +	}
> +
>   	/* create notification to user */
>   	msg_head.opcode  = RX_TIMEOUT;
>   	msg_head.flags   = op->flags;
> @@ -557,25 +562,6 @@ static void bcm_rx_timeout_tsklet(unsign
>   	msg_head.nframes = 0;
>   
>   	bcm_send_to_user(op, &msg_head, NULL, 0);
> -}
> -
> -/*
> - * bcm_rx_timeout_handler - when the (cyclic) CAN frame reception timed out
> - */
> -static enum hrtimer_restart bcm_rx_timeout_handler(struct hrtimer *hrtimer)
> -{
> -	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
> -
> -	/* schedule before NET_RX_SOFTIRQ */
> -	tasklet_hi_schedule(&op->tsklet);
> -
> -	/* no restart of the timer is done here! */
> -
> -	/* if user wants to be informed, when cyclic CAN-Messages come back */
> -	if ((op->flags & RX_ANNOUNCE_RESUME) && op->last_frames) {
> -		/* clear received CAN frames to indicate 'nothing received' */
> -		memset(op->last_frames, 0, op->nframes * op->cfsiz);
> -	}
>   
>   	return HRTIMER_NORESTART;
>   }
> @@ -583,14 +569,12 @@ static enum hrtimer_restart bcm_rx_timeo
>   /*
>    * bcm_rx_do_flush - helper for bcm_rx_thr_flush
>    */
> -static inline int bcm_rx_do_flush(struct bcm_op *op, int update,
> -				  unsigned int index)
> +static inline int bcm_rx_do_flush(struct bcm_op *op, unsigned int index)
>   {
>   	struct canfd_frame *lcf = op->last_frames + op->cfsiz * index;
>   
>   	if ((op->last_frames) && (lcf->flags & RX_THR)) {
> -		if (update)
> -			bcm_rx_changed(op, lcf);
> +		bcm_rx_changed(op, lcf);
>   		return 1;
>   	}
>   	return 0;
> @@ -598,11 +582,8 @@ static inline int bcm_rx_do_flush(struct
>   
>   /*
>    * bcm_rx_thr_flush - Check for throttled data and send it to the userspace
> - *
> - * update == 0 : just check if throttled data is available  (any irq context)
> - * update == 1 : check and send throttled data to userspace (soft_irq context)
>    */
> -static int bcm_rx_thr_flush(struct bcm_op *op, int update)
> +static int bcm_rx_thr_flush(struct bcm_op *op)
>   {
>   	int updated = 0;
>   
> @@ -611,24 +592,16 @@ static int bcm_rx_thr_flush(struct bcm_o
>   
>   		/* for MUX filter we start at index 1 */
>   		for (i = 1; i < op->nframes; i++)
> -			updated += bcm_rx_do_flush(op, update, i);
> +			updated += bcm_rx_do_flush(op, i);
>   
>   	} else {
>   		/* for RX_FILTER_ID and simple filter */
> -		updated += bcm_rx_do_flush(op, update, 0);
> +		updated += bcm_rx_do_flush(op, 0);
>   	}
>   
>   	return updated;
>   }
>   
> -static void bcm_rx_thr_tsklet(unsigned long data)
> -{
> -	struct bcm_op *op = (struct bcm_op *)data;
> -
> -	/* push the changed data to the userspace */
> -	bcm_rx_thr_flush(op, 1);
> -}
> -
>   /*
>    * bcm_rx_thr_handler - the time for blocked content updates is over now:
>    *                      Check for throttled data and send it to the userspace
> @@ -637,9 +610,7 @@ static enum hrtimer_restart bcm_rx_thr_h
>   {
>   	struct bcm_op *op = container_of(hrtimer, struct bcm_op, thrtimer);
>   
> -	tasklet_schedule(&op->thrtsklet);
> -
> -	if (bcm_rx_thr_flush(op, 0)) {
> +	if (bcm_rx_thr_flush(op)) {
>   		hrtimer_forward(hrtimer, ktime_get(), op->kt_ival2);
>   		return HRTIMER_RESTART;
>   	} else {
> @@ -735,23 +706,8 @@ static struct bcm_op *bcm_find_op(struct
>   
>   static void bcm_remove_op(struct bcm_op *op)
>   {
> -	if (op->tsklet.func) {
> -		while (test_bit(TASKLET_STATE_SCHED, &op->tsklet.state) ||
> -		       test_bit(TASKLET_STATE_RUN, &op->tsklet.state) ||
> -		       hrtimer_active(&op->timer)) {
> -			hrtimer_cancel(&op->timer);
> -			tasklet_kill(&op->tsklet);
> -		}
> -	}
> -
> -	if (op->thrtsklet.func) {
> -		while (test_bit(TASKLET_STATE_SCHED, &op->thrtsklet.state) ||
> -		       test_bit(TASKLET_STATE_RUN, &op->thrtsklet.state) ||
> -		       hrtimer_active(&op->thrtimer)) {
> -			hrtimer_cancel(&op->thrtimer);
> -			tasklet_kill(&op->thrtsklet);
> -		}
> -	}
> +	hrtimer_cancel(&op->timer);
> +	hrtimer_cancel(&op->thrtimer);
>   
>   	if ((op->frames) && (op->frames != &op->sframe))
>   		kfree(op->frames);
> @@ -979,15 +935,13 @@ static int bcm_tx_setup(struct bcm_msg_h
>   		op->ifindex = ifindex;
>   
>   		/* initialize uninitialized (kzalloc) structure */
> -		hrtimer_init(&op->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> +		hrtimer_init(&op->timer, CLOCK_MONOTONIC,
> +			     HRTIMER_MODE_REL_SOFT);
>   		op->timer.function = bcm_tx_timeout_handler;
>   
> -		/* initialize tasklet for tx countevent notification */
> -		tasklet_init(&op->tsklet, bcm_tx_timeout_tsklet,
> -			     (unsigned long) op);
> -
>   		/* currently unused in tx_ops */
> -		hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> +		hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC,
> +			     HRTIMER_MODE_REL_SOFT);
>   
>   		/* add this bcm_op to the list of the tx_ops */
>   		list_add(&op->list, &bo->tx_ops);
> @@ -1150,20 +1104,14 @@ static int bcm_rx_setup(struct bcm_msg_h
>   		op->rx_ifindex = ifindex;
>   
>   		/* initialize uninitialized (kzalloc) structure */
> -		hrtimer_init(&op->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> +		hrtimer_init(&op->timer, CLOCK_MONOTONIC,
> +			     HRTIMER_MODE_REL_SOFT);
>   		op->timer.function = bcm_rx_timeout_handler;
>   
> -		/* initialize tasklet for rx timeout notification */
> -		tasklet_init(&op->tsklet, bcm_rx_timeout_tsklet,
> -			     (unsigned long) op);
> -
> -		hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> +		hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC,
> +			     HRTIMER_MODE_REL_SOFT);
>   		op->thrtimer.function = bcm_rx_thr_handler;
>   
> -		/* initialize tasklet for rx throttle handling */
> -		tasklet_init(&op->thrtsklet, bcm_rx_thr_tsklet,
> -			     (unsigned long) op);
> -
>   		/* add this bcm_op to the list of the rx_ops */
>   		list_add(&op->list, &bo->rx_ops);
>   
> @@ -1209,12 +1157,12 @@ static int bcm_rx_setup(struct bcm_msg_h
>   			 */
>   			op->kt_lastmsg = 0;
>   			hrtimer_cancel(&op->thrtimer);
> -			bcm_rx_thr_flush(op, 1);
> +			bcm_rx_thr_flush(op);
>   		}
>   
>   		if ((op->flags & STARTTIMER) && op->kt_ival1)
>   			hrtimer_start(&op->timer, op->kt_ival1,
> -				      HRTIMER_MODE_REL);
> +				      HRTIMER_MODE_REL_SOFT);
>   	}
>   
>   	/* now we can register for can_ids, if we added a new bcm_op */
> 
> 

Re: [PATCH v2 28/37] hrtimer: Implement support for softirq based hrtimers

[Sebastian Andrzej Siewior]

On 2017-10-22 23:40:06 [+0200], Anna-Maria Gleixner wrote:
> --- a/include/linux/hrtimer.h
> +++ b/include/linux/hrtimer.h
> @@ -528,25 +546,42 @@ static ktime_t __hrtimer_next_event_base
>   * Recomputes cpu_base::*next_timer and returns the earliest expires_next but
>   * does not set cpu_base::*expires_next, that is done by hrtimer_reprogram.
>   *
> + * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
> + * those timers will get run whenever the softirq gets handled, at the end of
> + * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
> + *
> + * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
> + * The !softirq values are the minima across HRTIMER_ACTIVE, unless an actual
> + * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
> + *
>   * @active_mask must be one of:
>   *  - HRTIMER_ACTIVE,
>   *  - HRTIMER_ACTIVE_SOFT, or
>   *  - HRTIMER_ACTIVE_HARD.
>   */
> -static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base,
> -					unsigned int active_mask)
> +static ktime_t
> +__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
>  {
>  	unsigned int active;
> +	struct hrtimer *next_timer = NULL;
>  	ktime_t expires_next = KTIME_MAX;
>  
> -	cpu_base->next_timer = NULL;
> +	if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
> +		active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
> +		cpu_base->softirq_next_timer = next_timer;
> +		expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);

doing

               cpu_base->softirq_next_timer = NULL;
               expires_next = __hrtimer_next_event_base(cpu_base, active, KTIME_MAX);

instead would make it more obvious I think. I wasn't sure if it is a
typo and the timer assignment was meant to be after
__hrtimer_next_event_base() was invoked or if NULL was indeed intended.

> +
> +		next_timer = cpu_base->softirq_next_timer;
> +	}
>  
> -	active = cpu_base->active_bases & active_mask;
> -	expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
> +	if (active_mask & HRTIMER_ACTIVE_HARD) {
> +		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
> +		cpu_base->next_timer = next_timer;
> +		expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
> +	}
>  
>  	return expires_next;
>  }
> -#endif
>  
>  static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
>  {
> @@ -968,6 +1034,32 @@ static inline ktime_t hrtimer_update_low
>  	return tim;
>  }
>  
> +static void
> +hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
> +{
> +	ktime_t expires;
> +
> +	/*
> +	 * Find the next SOFT expiration.
> +	 */
> +	expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);

If you replace the following block
> +
> +	/*
> +	 * reprogramming needs to be triggered, even if the next soft
> +	 * hrtimer expires at the same time than the next hard
> +	 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
> +	 */
> +	if (!reprogram || expires == KTIME_MAX ||
> +	    ktime_before(expires, cpu_base->expires_next))
> +		return;

with 

       if (expires == KTIME_MAX)
               return;
       if (!reprogram || !ktime_before(expires, cpu_base->expires_next)) {

               /*
                * ->softirq_next_timer was updated by __hrtimer_next_event_base()
                * and we need to make sure that ->softirq_expires_next matches.
                */
               cpu_base->softirq_expires_next = expires;
               return;
       }

then you have two bug less I *think*.

If *expires* is before ->expires_next then you don't want to return and
do nothing but instead you want to reprogram timer for the soft-timer
event. 

And then even if *expires* is after ->expires_next then you need to
->softirq_expires_next. As the comment says, the next timer field has
been already updated. At this point, ->softirq_expires_next is set to
KTIME_MAX (due to the raise softirq part) so if this field is not
udpated here, then the hr-irq won't see the pending timer and expire it.
Even worse, if future soft-timer have a "later" expiry time then this
timer now then this field won't be updated at all and all soft-timer
processing will stall.

> +
> +	/*
> +	 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
> +	 * cpu_base->*expires_next is only set by hrtimer_reprogram()
> +	 */
> +	hrtimer_reprogram(cpu_base->softirq_next_timer);
> +}
> +

Sebastian

Re: [PATCH v2 28/37] hrtimer: Implement support for softirq based hrtimers

[Anna-Maria Gleixner]

On Fri, 10 Nov 2017, Sebastian Andrzej Siewior wrote:

> On 2017-10-22 23:40:06 [+0200], Anna-Maria Gleixner wrote:
> > --- a/include/linux/hrtimer.h
> > +++ b/include/linux/hrtimer.h
> > @@ -528,25 +546,42 @@ static ktime_t __hrtimer_next_event_base
> >   * Recomputes cpu_base::*next_timer and returns the earliest expires_next but
> >   * does not set cpu_base::*expires_next, that is done by hrtimer_reprogram.
> >   *
> > + * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
> > + * those timers will get run whenever the softirq gets handled, at the end of
> > + * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
> > + *
> > + * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
> > + * The !softirq values are the minima across HRTIMER_ACTIVE, unless an actual
> > + * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
> > + *
> >   * @active_mask must be one of:
> >   *  - HRTIMER_ACTIVE,
> >   *  - HRTIMER_ACTIVE_SOFT, or
> >   *  - HRTIMER_ACTIVE_HARD.
> >   */
> > -static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base,
> > -					unsigned int active_mask)
> > +static ktime_t
> > +__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
> >  {
> >  	unsigned int active;
> > +	struct hrtimer *next_timer = NULL;
> >  	ktime_t expires_next = KTIME_MAX;
> >  
> > -	cpu_base->next_timer = NULL;
> > +	if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
> > +		active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
> > +		cpu_base->softirq_next_timer = next_timer;
> > +		expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
> 
> doing
> 
>                cpu_base->softirq_next_timer = NULL;
>                expires_next = __hrtimer_next_event_base(cpu_base, active, KTIME_MAX);
> 
> instead would make it more obvious I think. I wasn't sure if it is a
> typo and the timer assignment was meant to be after
> __hrtimer_next_event_base() was invoked or if NULL was indeed intended.

will change it

> > +
> > +		next_timer = cpu_base->softirq_next_timer;
> > +	}
> >  
> > -	active = cpu_base->active_bases & active_mask;
> > -	expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
> > +	if (active_mask & HRTIMER_ACTIVE_HARD) {
> > +		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
> > +		cpu_base->next_timer = next_timer;
> > +		expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
> > +	}
> >  
> >  	return expires_next;
> >  }
> > -#endif
> >  
> >  static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
> >  {
> > @@ -968,6 +1034,32 @@ static inline ktime_t hrtimer_update_low
> >  	return tim;
> >  }
> >  
> > +static void
> > +hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
> > +{
> > +	ktime_t expires;
> > +
> > +	/*
> > +	 * Find the next SOFT expiration.
> > +	 */
> > +	expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
> 
> If you replace the following block
> > +
> > +	/*
> > +	 * reprogramming needs to be triggered, even if the next soft
> > +	 * hrtimer expires at the same time than the next hard
> > +	 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
> > +	 */
> > +	if (!reprogram || expires == KTIME_MAX ||
> > +	    ktime_before(expires, cpu_base->expires_next))
> > +		return;
> 
> with 
> 
>        if (expires == KTIME_MAX)
>                return;
>        if (!reprogram || !ktime_before(expires, cpu_base->expires_next)) {
> 
>                /*
>                 * ->softirq_next_timer was updated by __hrtimer_next_event_base()
>                 * and we need to make sure that ->softirq_expires_next matches.
>                 */
>                cpu_base->softirq_expires_next = expires;
>                return;
>        }
> 
> then you have two bug less I *think*.
> 
> If *expires* is before ->expires_next then you don't want to return and
> do nothing but instead you want to reprogram timer for the soft-timer
> event. 
> 
> And then even if *expires* is after ->expires_next then you need to
> ->softirq_expires_next. As the comment says, the next timer field has
> been already updated. At this point, ->softirq_expires_next is set to
> KTIME_MAX (due to the raise softirq part) so if this field is not
> udpated here, then the hr-irq won't see the pending timer and expire it.
> Even worse, if future soft-timer have a "later" expiry time then this
> timer now then this field won't be updated at all and all soft-timer
> processing will stall.
>

I would propse another solution for this:

	if (expires == KTIME_MAX)
		return;

	hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);

Updating of cpu_base::*expires_next values is done in
hrtimer_reprogram() only. I think this should not change. When expires
equals KTIME_MAX, there is no soft hrtimer queued and updating of
softirq_expires_next is not required. The hrtimer_reprogram() function
gets the reprogram parameter handed in. If this parameter is set, the
hrtimer_reprogram() returns after setting the softirq_expires_next
value. In the migration case the hardware is not reprogrammed. If the
first soft hrtimer expires after the first hard hrtimer, then
hrtimer_reprogram() returns without reprogramming anyway.

> > +
> > +	/*
> > +	 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
> > +	 * cpu_base->*expires_next is only set by hrtimer_reprogram()
> > +	 */
> > +	hrtimer_reprogram(cpu_base->softirq_next_timer);
> > +}
> > +
> 
> Sebastian
> 

Anna-Maria