* [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
@ 2012-07-17 17:33 John Stultz
2012-07-17 17:33 ` [PATCH 01/11] 3.0.x: ntp: Fix leap-second hrtimer livelock John Stultz
` (12 more replies)
0 siblings, 13 replies; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable; +Cc: John Stultz, Prarit Bhargava, Thomas Gleixner, Linux Kernel
Here is backport of the leapsecond fixes to 3.0-stable. These are less
straight forward, and should get closer review.
This patch set addresses two issues:
1) Deadlock leapsecond issue that a few reports described.
I spent some time over the weekend trying to find a way to reproduce
the hard-hang issue some folks were reporting after the leapsecond.
Initially I didn't think the 6b43ae8a619d17 leap-second hrimter livelock
patch needed to be backported since, I assumed it required the ntp_lock
split for it to be triggered, but looking again I found that the same
issue could occur prior to splitting out the ntp_lock. So I've backported
that fix (and its follow-on fixups) as well as created a test case
to reproduce the hard-hang deadlock.
2) Early hrtimer/futex expiration issue that was more widely observed
This is the load-spike issue that a number of folks saw that did not
hard hang most boxes (although some reports did show nmi-watchdogs
triggering due to sudden spinning in tight loops).
I've booted and tested this entire patchset on two boxes and run through a
number of leapsecond related stress tests. However, additional testing and
review would be appreciated.
The original commits backported in this set are:
Deadlock issue fixes:
---------------------
6b43ae8a619d17c4935c3320d2ef9e92bdeed05d ntp: Fix leap-second hrtimer livelock
dd48d708ff3e917f6d6b6c2b696c3f18c019feed ntp: Correct TAI offset during leap second
fad0c66c4bb836d57a5f125ecd38bed653ca863a timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond
Helper change: (allows the following fixes to backport more easily):
--------------------------------------------------------------------
cc06268c6a87db156af2daed6e96a936b955cc82 time: Move common updates to a function
Hrtimer early-expiration issue fixes:
-------------------------------
f55a6faa384304c89cfef162768e88374d3312cb hrtimer: Provide clock_was_set_delayed()
4873fa070ae84a4115f0b3c9dfabc224f1bc7c51 timekeeping: Fix leapsecond triggered load spike issue
5b9fe759a678e05be4937ddf03d50e950207c1c0 timekeeping: Maintain ktime_t based offsets for hrtimers
196951e91262fccda81147d2bcf7fdab08668b40 hrtimers: Move lock held region in hrtimer_interrupt()
f6c06abfb3972ad4914cef57d8348fcb2932bc3b timekeeping: Provide hrtimer update function
5baefd6d84163443215f4a99f6a20f054ef11236 hrtimer: Update hrtimer base offsets each hrtimer_interrupt
3e997130bd2e8c6f5aaa49d6e3161d4d29b43ab0 timekeeping: Add missing update call in timekeeping_resume()
I've already done backports to all the stable kernels to 2.6.32, and
will send out the rest soon.
Please let me know if you have any comments or feedback.
thanks
-john
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
John Stultz (5):
3.0.x: ntp: Fix leap-second hrtimer livelock
3.0.x: timekeeping: Fix CLOCK_MONOTONIC inconsistency during
leapsecond
3.0.x: hrtimer: Provide clock_was_set_delayed()
3.0.x: timekeeping: Fix leapsecond triggered load spike issue
3.0.x: hrtimer: Update hrtimer base offsets each hrtimer_interrupt
Richard Cochran (1):
3.0.x: ntp: Correct TAI offset during leap second
Thomas Gleixner (5):
3.0.x: time: Move common updates to a function
3.0.x: timekeeping: Maintain ktime_t based offsets for hrtimers
3.0.x: hrtimers: Move lock held region in hrtimer_interrupt()
3.0.x: timekeeping: Provide hrtimer update function
3.0.x: timekeeping: Add missing update call in timekeeping_resume()
include/linux/hrtimer.h | 10 +++-
include/linux/timex.h | 2 +-
kernel/hrtimer.c | 53 +++++++++++++------
kernel/time/ntp.c | 124 +++++++++++++++------------------------------
kernel/time/timekeeping.c | 115 +++++++++++++++++++++++++++++++----------
5 files changed, 175 insertions(+), 129 deletions(-)
--
1.7.9.5
^ permalink raw reply [flat|nested] 33+ messages in thread
* [PATCH 01/11] 3.0.x: ntp: Fix leap-second hrtimer livelock
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "ntp: Fix leap-second hrtimer livelock" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 02/11] 3.0.x: ntp: Correct TAI offset during leap second John Stultz
` (11 subsequent siblings)
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable
Cc: John Stultz, Sasha Levin, Thomas Gleixner, Prarit Bhargava, Linux Kernel
From: John Stultz <john.stultz@linaro.org>
This is a backport of 6b43ae8a619d17c4935c3320d2ef9e92bdeed05d
This should have been backported when it was commited, but I
mistook the problem as requiring the ntp_lock changes
that landed in 3.4 in order for it to occur.
Unfortunately the same issue can happen (with only one cpu)
as follows:
do_adjtimex()
write_seqlock_irq(&xtime_lock);
process_adjtimex_modes()
process_adj_status()
ntp_start_leap_timer()
hrtimer_start()
hrtimer_reprogram()
tick_program_event()
clockevents_program_event()
ktime_get()
seq = req_seqbegin(xtime_lock); [DEADLOCK]
This deadlock will no always occur, as it requires the
leap_timer to force a hrtimer_reprogram which only happens
if its set and there's no sooner timer to expire.
NOTE: This patch, being faithful to the original commit,
introduces a bug (we don't update wall_to_monotonic),
which will be resovled by backporting a following fix.
Original commit message below:
Since commit 7dffa3c673fbcf835cd7be80bb4aec8ad3f51168 the ntp
subsystem has used an hrtimer for triggering the leapsecond
adjustment. However, this can cause a potential livelock.
Thomas diagnosed this as the following pattern:
CPU 0 CPU 1
do_adjtimex()
spin_lock_irq(&ntp_lock);
process_adjtimex_modes(); timer_interrupt()
process_adj_status(); do_timer()
ntp_start_leap_timer(); write_lock(&xtime_lock);
hrtimer_start(); update_wall_time();
hrtimer_reprogram(); ntp_tick_length()
tick_program_event() spin_lock(&ntp_lock);
clockevents_program_event()
ktime_get()
seq = req_seqbegin(xtime_lock);
This patch tries to avoid the problem by reverting back to not using
an hrtimer to inject leapseconds, and instead we handle the leapsecond
processing in the second_overflow() function.
The downside to this change is that on systems that support highres
timers, the leap second processing will occur on a HZ tick boundary,
(ie: ~1-10ms, depending on HZ) after the leap second instead of
possibly sooner (~34us in my tests w/ x86_64 lapic).
This patch applies on top of tip/timers/core.
CC: Sasha Levin <levinsasha928@gmail.com>
CC: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Diagnoised-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
include/linux/timex.h | 2 +-
kernel/time/ntp.c | 122 +++++++++++++++------------------------------
kernel/time/timekeeping.c | 18 +++----
3 files changed, 48 insertions(+), 94 deletions(-)
diff --git a/include/linux/timex.h b/include/linux/timex.h
index aa60fe7..08e90fb 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -266,7 +266,7 @@ static inline int ntp_synced(void)
/* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */
extern u64 tick_length;
-extern void second_overflow(void);
+extern int second_overflow(unsigned long secs);
extern void update_ntp_one_tick(void);
extern int do_adjtimex(struct timex *);
extern void hardpps(const struct timespec *, const struct timespec *);
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 4b85a7a..4508f7f 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -31,8 +31,6 @@ unsigned long tick_nsec;
u64 tick_length;
static u64 tick_length_base;
-static struct hrtimer leap_timer;
-
#define MAX_TICKADJ 500LL /* usecs */
#define MAX_TICKADJ_SCALED \
(((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
@@ -350,60 +348,60 @@ void ntp_clear(void)
}
/*
- * Leap second processing. If in leap-insert state at the end of the
- * day, the system clock is set back one second; if in leap-delete
- * state, the system clock is set ahead one second.
+ * this routine handles the overflow of the microsecond field
+ *
+ * The tricky bits of code to handle the accurate clock support
+ * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
+ * They were originally developed for SUN and DEC kernels.
+ * All the kudos should go to Dave for this stuff.
+ *
+ * Also handles leap second processing, and returns leap offset
*/
-static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
+int second_overflow(unsigned long secs)
{
- enum hrtimer_restart res = HRTIMER_NORESTART;
-
- write_seqlock(&xtime_lock);
+ int leap = 0;
+ s64 delta;
+ /*
+ * Leap second processing. If in leap-insert state at the end of the
+ * day, the system clock is set back one second; if in leap-delete
+ * state, the system clock is set ahead one second.
+ */
switch (time_state) {
case TIME_OK:
+ if (time_status & STA_INS)
+ time_state = TIME_INS;
+ else if (time_status & STA_DEL)
+ time_state = TIME_DEL;
break;
case TIME_INS:
- timekeeping_leap_insert(-1);
- time_state = TIME_OOP;
- printk(KERN_NOTICE
- "Clock: inserting leap second 23:59:60 UTC\n");
- hrtimer_add_expires_ns(&leap_timer, NSEC_PER_SEC);
- res = HRTIMER_RESTART;
+ if (secs % 86400 == 0) {
+ leap = -1;
+ time_state = TIME_OOP;
+ printk(KERN_NOTICE
+ "Clock: inserting leap second 23:59:60 UTC\n");
+ }
break;
case TIME_DEL:
- timekeeping_leap_insert(1);
- time_tai--;
- time_state = TIME_WAIT;
- printk(KERN_NOTICE
- "Clock: deleting leap second 23:59:59 UTC\n");
+ if ((secs + 1) % 86400 == 0) {
+ leap = 1;
+ time_tai--;
+ time_state = TIME_WAIT;
+ printk(KERN_NOTICE
+ "Clock: deleting leap second 23:59:59 UTC\n");
+ }
break;
case TIME_OOP:
time_tai++;
time_state = TIME_WAIT;
- /* fall through */
+ break;
+
case TIME_WAIT:
if (!(time_status & (STA_INS | STA_DEL)))
time_state = TIME_OK;
break;
}
- write_sequnlock(&xtime_lock);
-
- return res;
-}
-
-/*
- * this routine handles the overflow of the microsecond field
- *
- * The tricky bits of code to handle the accurate clock support
- * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
- * They were originally developed for SUN and DEC kernels.
- * All the kudos should go to Dave for this stuff.
- */
-void second_overflow(void)
-{
- s64 delta;
/* Bump the maxerror field */
time_maxerror += MAXFREQ / NSEC_PER_USEC;
@@ -423,23 +421,25 @@ void second_overflow(void)
pps_dec_valid();
if (!time_adjust)
- return;
+ goto out;
if (time_adjust > MAX_TICKADJ) {
time_adjust -= MAX_TICKADJ;
tick_length += MAX_TICKADJ_SCALED;
- return;
+ goto out;
}
if (time_adjust < -MAX_TICKADJ) {
time_adjust += MAX_TICKADJ;
tick_length -= MAX_TICKADJ_SCALED;
- return;
+ goto out;
}
tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
<< NTP_SCALE_SHIFT;
time_adjust = 0;
+out:
+ return leap;
}
#ifdef CONFIG_GENERIC_CMOS_UPDATE
@@ -501,27 +501,6 @@ static void notify_cmos_timer(void)
static inline void notify_cmos_timer(void) { }
#endif
-/*
- * Start the leap seconds timer:
- */
-static inline void ntp_start_leap_timer(struct timespec *ts)
-{
- long now = ts->tv_sec;
-
- if (time_status & STA_INS) {
- time_state = TIME_INS;
- now += 86400 - now % 86400;
- hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS);
-
- return;
- }
-
- if (time_status & STA_DEL) {
- time_state = TIME_DEL;
- now += 86400 - (now + 1) % 86400;
- hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS);
- }
-}
/*
* Propagate a new txc->status value into the NTP state:
@@ -546,22 +525,6 @@ static inline void process_adj_status(struct timex *txc, struct timespec *ts)
time_status &= STA_RONLY;
time_status |= txc->status & ~STA_RONLY;
- switch (time_state) {
- case TIME_OK:
- ntp_start_leap_timer(ts);
- break;
- case TIME_INS:
- case TIME_DEL:
- time_state = TIME_OK;
- ntp_start_leap_timer(ts);
- case TIME_WAIT:
- if (!(time_status & (STA_INS | STA_DEL)))
- time_state = TIME_OK;
- break;
- case TIME_OOP:
- hrtimer_restart(&leap_timer);
- break;
- }
}
/*
* Called with the xtime lock held, so we can access and modify
@@ -643,9 +606,6 @@ int do_adjtimex(struct timex *txc)
(txc->tick < 900000/USER_HZ ||
txc->tick > 1100000/USER_HZ))
return -EINVAL;
-
- if (txc->modes & ADJ_STATUS && time_state != TIME_OK)
- hrtimer_cancel(&leap_timer);
}
if (txc->modes & ADJ_SETOFFSET) {
@@ -967,6 +927,4 @@ __setup("ntp_tick_adj=", ntp_tick_adj_setup);
void __init ntp_init(void)
{
ntp_clear();
- hrtimer_init(&leap_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
- leap_timer.function = ntp_leap_second;
}
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 5f45831..c444da0 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -169,15 +169,6 @@ static struct timespec raw_time;
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
-/* must hold xtime_lock */
-void timekeeping_leap_insert(int leapsecond)
-{
- xtime.tv_sec += leapsecond;
- wall_to_monotonic.tv_sec -= leapsecond;
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
-}
-
/**
* timekeeping_forward_now - update clock to the current time
*
@@ -828,9 +819,11 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
while (timekeeper.xtime_nsec >= nsecps) {
+ int leap;
timekeeper.xtime_nsec -= nsecps;
xtime.tv_sec++;
- second_overflow();
+ leap = second_overflow(xtime.tv_sec);
+ xtime.tv_sec += leap;
}
/* Accumulate raw time */
@@ -936,9 +929,12 @@ static void update_wall_time(void)
* xtime.tv_nsec isn't larger then NSEC_PER_SEC
*/
if (unlikely(xtime.tv_nsec >= NSEC_PER_SEC)) {
+ int leap;
xtime.tv_nsec -= NSEC_PER_SEC;
xtime.tv_sec++;
- second_overflow();
+ leap = second_overflow(xtime.tv_sec);
+ xtime.tv_sec += leap;
+
}
/* check to see if there is a new clocksource to use */
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 02/11] 3.0.x: ntp: Correct TAI offset during leap second
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
2012-07-17 17:33 ` [PATCH 01/11] 3.0.x: ntp: Fix leap-second hrtimer livelock John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "ntp: Correct TAI offset during leap second" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 03/11] 3.0.x: timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond John Stultz
` (10 subsequent siblings)
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable
Cc: Richard Cochran, Prarit Bhargava, Thomas Gleixner, Linux Kernel,
John Stultz
From: Richard Cochran <richardcochran@gmail.com>
This is a backport of dd48d708ff3e917f6d6b6c2b696c3f18c019feed
When repeating a UTC time value during a leap second (when the UTC
time should be 23:59:60), the TAI timescale should not stop. The kernel
NTP code increments the TAI offset one second too late. This patch fixes
the issue by incrementing the offset during the leap second itself.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
kernel/time/ntp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 4508f7f..f1eb182 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -378,6 +378,7 @@ int second_overflow(unsigned long secs)
if (secs % 86400 == 0) {
leap = -1;
time_state = TIME_OOP;
+ time_tai++;
printk(KERN_NOTICE
"Clock: inserting leap second 23:59:60 UTC\n");
}
@@ -392,7 +393,6 @@ int second_overflow(unsigned long secs)
}
break;
case TIME_OOP:
- time_tai++;
time_state = TIME_WAIT;
break;
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 03/11] 3.0.x: timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
2012-07-17 17:33 ` [PATCH 01/11] 3.0.x: ntp: Fix leap-second hrtimer livelock John Stultz
2012-07-17 17:33 ` [PATCH 02/11] 3.0.x: ntp: Correct TAI offset during leap second John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 04/11] 3.0.x: time: Move common updates to a function John Stultz
` (9 subsequent siblings)
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable
Cc: John Stultz, Thomas Gleixner, Prarit Bhargava, Linux Kernel, John Stultz
From: John Stultz <john.stultz@linaro.org>
This is a backport of fad0c66c4bb836d57a5f125ecd38bed653ca863a
which resolves a bug the previous commit.
Commit 6b43ae8a61 (ntp: Fix leap-second hrtimer livelock) broke the
leapsecond update of CLOCK_MONOTONIC. The missing leapsecond update to
wall_to_monotonic causes discontinuities in CLOCK_MONOTONIC.
Adjust wall_to_monotonic when NTP inserted a leapsecond.
Reported-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Tested-by: Richard Cochran <richardcochran@gmail.com>
Link: http://lkml.kernel.org/r/1338400497-12420-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
---
kernel/time/timekeeping.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index c444da0..ac5b225 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -824,6 +824,7 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
xtime.tv_sec++;
leap = second_overflow(xtime.tv_sec);
xtime.tv_sec += leap;
+ wall_to_monotonic.tv_sec -= leap;
}
/* Accumulate raw time */
@@ -934,7 +935,7 @@ static void update_wall_time(void)
xtime.tv_sec++;
leap = second_overflow(xtime.tv_sec);
xtime.tv_sec += leap;
-
+ wall_to_monotonic.tv_sec -= leap;
}
/* check to see if there is a new clocksource to use */
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 04/11] 3.0.x: time: Move common updates to a function
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (2 preceding siblings ...)
2012-07-17 17:33 ` [PATCH 03/11] 3.0.x: timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 17:49 ` Jonathan Nieder
2012-07-17 22:50 ` Patch "time: Move common updates to a function" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 05/11] 3.0.x: hrtimer: Provide clock_was_set_delayed() John Stultz
` (8 subsequent siblings)
12 siblings, 2 replies; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable
Cc: Thomas Gleixner, Eric Dumazet, Richard Cochran, Prarit Bhargava,
Linux Kernel, John Stultz
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of cc06268c6a87db156af2daed6e96a936b955cc82
While not a bugfix itself, it allows following fixes to backport
in a more straightforward manner.
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
kernel/time/timekeeping.c | 34 +++++++++++++++++-----------------
1 file changed, 17 insertions(+), 17 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index ac5b225..0b582eb 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -166,6 +166,19 @@ static struct timespec total_sleep_time;
*/
static struct timespec raw_time;
+/* must hold write on xtime_lock */
+static void timekeeping_update(bool clearntp)
+{
+ if (clearntp) {
+ timekeeper.ntp_error = 0;
+ ntp_clear();
+ }
+ update_vsyscall(&xtime, &wall_to_monotonic,
+ timekeeper.clock, timekeeper.mult);
+}
+
+
+
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
@@ -366,11 +379,7 @@ int do_settimeofday(const struct timespec *tv)
xtime = *tv;
- timekeeper.ntp_error = 0;
- ntp_clear();
-
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
+ timekeeping_update(true);
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -403,11 +412,7 @@ int timekeeping_inject_offset(struct timespec *ts)
xtime = timespec_add(xtime, *ts);
wall_to_monotonic = timespec_sub(wall_to_monotonic, *ts);
- timekeeper.ntp_error = 0;
- ntp_clear();
-
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
+ timekeeping_update(true);
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -630,10 +635,7 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
__timekeeping_inject_sleeptime(delta);
- timekeeper.ntp_error = 0;
- ntp_clear();
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
+ timekeeping_update(true);
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -938,9 +940,7 @@ static void update_wall_time(void)
wall_to_monotonic.tv_sec -= leap;
}
- /* check to see if there is a new clocksource to use */
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
+ timekeeping_update(false);
}
/**
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 05/11] 3.0.x: hrtimer: Provide clock_was_set_delayed()
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (3 preceding siblings ...)
2012-07-17 17:33 ` [PATCH 04/11] 3.0.x: time: Move common updates to a function John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "hrtimer: Provide clock_was_set_delayed()" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 06/11] 3.0.x: timekeeping: Fix leapsecond triggered load spike issue John Stultz
` (7 subsequent siblings)
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable; +Cc: John Stultz, Thomas Gleixner, Prarit Bhargava, Linux Kernel
This is a backport of f55a6faa384304c89cfef162768e88374d3312cb
clock_was_set() cannot be called from hard interrupt context because
it calls on_each_cpu().
For fixing the widely reported leap seconds issue it is necessary to
call it from hard interrupt context, i.e. the timer tick code, which
does the timekeeping updates.
Provide a new function which denotes it in the hrtimer cpu base
structure of the cpu on which it is called and raise the hrtimer
softirq. We then execute the clock_was_set() notificiation from
softirq context in run_hrtimer_softirq(). The hrtimer softirq is
rarely used, so polling the flag there is not a performance issue.
[ tglx: Made it depend on CONFIG_HIGH_RES_TIMERS. We really should get
rid of all this ifdeffery ASAP ]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reported-by: Jan Engelhardt <jengelh@inai.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-2-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
---
include/linux/hrtimer.h | 9 ++++++++-
kernel/hrtimer.c | 20 ++++++++++++++++++++
2 files changed, 28 insertions(+), 1 deletion(-)
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index fd0dc30..c9ec940 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -165,6 +165,7 @@ enum hrtimer_base_type {
* @lock: lock protecting the base and associated clock bases
* and timers
* @active_bases: Bitfield to mark bases with active timers
+ * @clock_was_set: Indicates that clock was set from irq context.
* @expires_next: absolute time of the next event which was scheduled
* via clock_set_next_event()
* @hres_active: State of high resolution mode
@@ -177,7 +178,8 @@ enum hrtimer_base_type {
*/
struct hrtimer_cpu_base {
raw_spinlock_t lock;
- unsigned long active_bases;
+ unsigned int active_bases;
+ unsigned int clock_was_set;
#ifdef CONFIG_HIGH_RES_TIMERS
ktime_t expires_next;
int hres_active;
@@ -286,6 +288,8 @@ extern void hrtimer_peek_ahead_timers(void);
# define MONOTONIC_RES_NSEC HIGH_RES_NSEC
# define KTIME_MONOTONIC_RES KTIME_HIGH_RES
+extern void clock_was_set_delayed(void);
+
#else
# define MONOTONIC_RES_NSEC LOW_RES_NSEC
@@ -306,6 +310,9 @@ static inline int hrtimer_is_hres_active(struct hrtimer *timer)
{
return 0;
}
+
+static inline void clock_was_set_delayed(void) { }
+
#endif
extern void clock_was_set(void);
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 2043c08..a256bab 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -717,6 +717,19 @@ static int hrtimer_switch_to_hres(void)
return 1;
}
+/*
+ * Called from timekeeping code to reprogramm the hrtimer interrupt
+ * device. If called from the timer interrupt context we defer it to
+ * softirq context.
+ */
+void clock_was_set_delayed(void)
+{
+ struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+
+ cpu_base->clock_was_set = 1;
+ __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+}
+
#else
static inline int hrtimer_hres_active(void) { return 0; }
@@ -1395,6 +1408,13 @@ void hrtimer_peek_ahead_timers(void)
static void run_hrtimer_softirq(struct softirq_action *h)
{
+ struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+
+ if (cpu_base->clock_was_set) {
+ cpu_base->clock_was_set = 0;
+ clock_was_set();
+ }
+
hrtimer_peek_ahead_timers();
}
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 06/11] 3.0.x: timekeeping: Fix leapsecond triggered load spike issue
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (4 preceding siblings ...)
2012-07-17 17:33 ` [PATCH 05/11] 3.0.x: hrtimer: Provide clock_was_set_delayed() John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Fix leapsecond triggered load spike issue" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 07/11] 3.0.x: timekeeping: Maintain ktime_t based offsets for hrtimers John Stultz
` (6 subsequent siblings)
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable; +Cc: John Stultz, Thomas Gleixner, Prarit Bhargava, Linux Kernel
This is a backport of 4873fa070ae84a4115f0b3c9dfabc224f1bc7c51
The timekeeping code misses an update of the hrtimer subsystem after a
leap second happened. Due to that timers based on CLOCK_REALTIME are
either expiring a second early or late depending on whether a leap
second has been inserted or deleted until an operation is initiated
which causes that update. Unless the update happens by some other
means this discrepancy between the timekeeping and the hrtimer data
stays forever and timers are expired either early or late.
The reported immediate workaround - $ data -s "`date`" - is causing a
call to clock_was_set() which updates the hrtimer data structures.
See: http://www.sheeri.com/content/mysql-and-leap-second-high-cpu-and-fix
Add the missing clock_was_set() call to update_wall_time() in case of
a leap second event. The actual update is deferred to softirq context
as the necessary smp function call cannot be invoked from hard
interrupt context.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reported-by: Jan Engelhardt <jengelh@inai.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-3-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
---
kernel/time/timekeeping.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 0b582eb..9201474 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -827,6 +827,8 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
leap = second_overflow(xtime.tv_sec);
xtime.tv_sec += leap;
wall_to_monotonic.tv_sec -= leap;
+ if (leap)
+ clock_was_set_delayed();
}
/* Accumulate raw time */
@@ -938,6 +940,8 @@ static void update_wall_time(void)
leap = second_overflow(xtime.tv_sec);
xtime.tv_sec += leap;
wall_to_monotonic.tv_sec -= leap;
+ if (leap)
+ clock_was_set_delayed();
}
timekeeping_update(false);
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 07/11] 3.0.x: timekeeping: Maintain ktime_t based offsets for hrtimers
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (5 preceding siblings ...)
2012-07-17 17:33 ` [PATCH 06/11] 3.0.x: timekeeping: Fix leapsecond triggered load spike issue John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Maintain ktime_t based offsets for hrtimers" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 08/11] 3.0.x: hrtimers: Move lock held region in hrtimer_interrupt() John Stultz
` (5 subsequent siblings)
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable; +Cc: Thomas Gleixner, John Stultz, Prarit Bhargava, Linux Kernel
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of 5b9fe759a678e05be4937ddf03d50e950207c1c0
We need to update the hrtimer clock offsets from the hrtimer interrupt
context. To avoid conversions from timespec to ktime_t maintain a
ktime_t based representation of those offsets in the timekeeper. This
puts the conversion overhead into the code which updates the
underlying offsets and provides fast accessible values in the hrtimer
interrupt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-4-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
---
kernel/time/timekeeping.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 9201474..d647773 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -161,18 +161,34 @@ static struct timespec xtime __attribute__ ((aligned (16)));
static struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
static struct timespec total_sleep_time;
+/* Offset clock monotonic -> clock realtime */
+static ktime_t offs_real;
+
+/* Offset clock monotonic -> clock boottime */
+static ktime_t offs_boot;
+
/*
* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
*/
static struct timespec raw_time;
/* must hold write on xtime_lock */
+static void update_rt_offset(void)
+{
+ struct timespec tmp, *wtm = &wall_to_monotonic;
+
+ set_normalized_timespec(&tmp, -wtm->tv_sec, -wtm->tv_nsec);
+ offs_real = timespec_to_ktime(tmp);
+}
+
+/* must hold write on xtime_lock */
static void timekeeping_update(bool clearntp)
{
if (clearntp) {
timekeeper.ntp_error = 0;
ntp_clear();
}
+ update_rt_offset();
update_vsyscall(&xtime, &wall_to_monotonic,
timekeeper.clock, timekeeper.mult);
}
@@ -587,6 +603,7 @@ void __init timekeeping_init(void)
}
set_normalized_timespec(&wall_to_monotonic,
-boot.tv_sec, -boot.tv_nsec);
+ update_rt_offset();
total_sleep_time.tv_sec = 0;
total_sleep_time.tv_nsec = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -595,6 +612,12 @@ void __init timekeeping_init(void)
/* time in seconds when suspend began */
static struct timespec timekeeping_suspend_time;
+static void update_sleep_time(struct timespec t)
+{
+ total_sleep_time = t;
+ offs_boot = timespec_to_ktime(t);
+}
+
/**
* __timekeeping_inject_sleeptime - Internal function to add sleep interval
* @delta: pointer to a timespec delta value
@@ -606,7 +629,7 @@ static void __timekeeping_inject_sleeptime(struct timespec *delta)
{
xtime = timespec_add(xtime, *delta);
wall_to_monotonic = timespec_sub(wall_to_monotonic, *delta);
- total_sleep_time = timespec_add(total_sleep_time, *delta);
+ update_sleep_time(timespec_add(total_sleep_time, *delta));
}
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 08/11] 3.0.x: hrtimers: Move lock held region in hrtimer_interrupt()
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (6 preceding siblings ...)
2012-07-17 17:33 ` [PATCH 07/11] 3.0.x: timekeeping: Maintain ktime_t based offsets for hrtimers John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "hrtimers: Move lock held region in hrtimer_interrupt()" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 09/11] 3.0.x: timekeeping: Provide hrtimer update function John Stultz
` (4 subsequent siblings)
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable; +Cc: Thomas Gleixner, John Stultz, Prarit Bhargava, Linux Kernel
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of 196951e91262fccda81147d2bcf7fdab08668b40
We need to update the base offsets from this code and we need to do
that under base->lock. Move the lock held region around the
ktime_get() calls. The ktime_get() calls are going to be replaced with
a function which gets the time and the offsets atomically.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/1341960205-56738-6-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
---
kernel/hrtimer.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index a256bab..8fc6533 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1263,11 +1263,10 @@ void hrtimer_interrupt(struct clock_event_device *dev)
cpu_base->nr_events++;
dev->next_event.tv64 = KTIME_MAX;
+ raw_spin_lock(&cpu_base->lock);
entry_time = now = ktime_get();
retry:
expires_next.tv64 = KTIME_MAX;
-
- raw_spin_lock(&cpu_base->lock);
/*
* We set expires_next to KTIME_MAX here with cpu_base->lock
* held to prevent that a timer is enqueued in our queue via
@@ -1344,6 +1343,7 @@ retry:
* interrupt routine. We give it 3 attempts to avoid
* overreacting on some spurious event.
*/
+ raw_spin_lock(&cpu_base->lock);
now = ktime_get();
cpu_base->nr_retries++;
if (++retries < 3)
@@ -1356,6 +1356,7 @@ retry:
*/
cpu_base->nr_hangs++;
cpu_base->hang_detected = 1;
+ raw_spin_unlock(&cpu_base->lock);
delta = ktime_sub(now, entry_time);
if (delta.tv64 > cpu_base->max_hang_time.tv64)
cpu_base->max_hang_time = delta;
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 09/11] 3.0.x: timekeeping: Provide hrtimer update function
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (7 preceding siblings ...)
2012-07-17 17:33 ` [PATCH 08/11] 3.0.x: hrtimers: Move lock held region in hrtimer_interrupt() John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Provide hrtimer update function" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 10/11] 3.0.x: hrtimer: Update hrtimer base offsets each hrtimer_interrupt John Stultz
` (3 subsequent siblings)
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable; +Cc: Thomas Gleixner, John Stultz, Prarit Bhargava, Linux Kernel
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of f6c06abfb3972ad4914cef57d8348fcb2932bc3b
To finally fix the infamous leap second issue and other race windows
caused by functions which change the offsets between the various time
bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a
function which atomically gets the current monotonic time and updates
the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic
overhead. The previous patch which provides ktime_t offsets allows us
to make this function almost as cheap as ktime_get() which is going to
be replaced in hrtimer_interrupt().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
---
include/linux/hrtimer.h | 1 +
kernel/time/timekeeping.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index c9ec940..cc07d27 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -327,6 +327,7 @@ extern ktime_t ktime_get(void);
extern ktime_t ktime_get_real(void);
extern ktime_t ktime_get_boottime(void);
extern ktime_t ktime_get_monotonic_offset(void);
+extern ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot);
DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index d647773..f0c7565 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1126,6 +1126,40 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
} while (read_seqretry(&xtime_lock, seq));
}
+#ifdef CONFIG_HIGH_RES_TIMERS
+/**
+ * ktime_get_update_offsets - hrtimer helper
+ * @real: pointer to storage for monotonic -> realtime offset
+ * @_boot: pointer to storage for monotonic -> boottime offset
+ *
+ * Returns current monotonic time and updates the offsets
+ * Called from hrtimer_interupt() or retrigger_next_event()
+ */
+ktime_t ktime_get_update_offsets(ktime_t *real, ktime_t *boot)
+{
+ ktime_t now;
+ unsigned int seq;
+ u64 secs, nsecs;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+
+ secs = xtime.tv_sec;
+ nsecs = xtime.tv_nsec;
+ nsecs += timekeeping_get_ns();
+ /* If arch requires, add in gettimeoffset() */
+ nsecs += arch_gettimeoffset();
+
+ *real = offs_real;
+ *boot = offs_boot;
+ } while (read_seqretry(&xtime_lock, seq));
+
+ now = ktime_add_ns(ktime_set(secs, 0), nsecs);
+ now = ktime_sub(now, *real);
+ return now;
+}
+#endif
+
/**
* ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
*/
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 10/11] 3.0.x: hrtimer: Update hrtimer base offsets each hrtimer_interrupt
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (8 preceding siblings ...)
2012-07-17 17:33 ` [PATCH 09/11] 3.0.x: timekeeping: Provide hrtimer update function John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "hrtimer: Update hrtimer base offsets each hrtimer_interrupt" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 11/11] 3.0.x: timekeeping: Add missing update call in timekeeping_resume() John Stultz
` (2 subsequent siblings)
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable; +Cc: John Stultz, Thomas Gleixner, Prarit Bhargava, Linux Kernel
This is a backport of 5baefd6d84163443215f4a99f6a20f054ef11236
The update of the hrtimer base offsets on all cpus cannot be made
atomically from the timekeeper.lock held and interrupt disabled region
as smp function calls are not allowed there.
clock_was_set(), which enforces the update on all cpus, is called
either from preemptible process context in case of do_settimeofday()
or from the softirq context when the offset modification happened in
the timer interrupt itself due to a leap second.
In both cases there is a race window for an hrtimer interrupt between
dropping timekeeper lock, enabling interrupts and clock_was_set()
issuing the updates. Any interrupt which arrives in that window will
see the new time but operate on stale offsets.
So we need to make sure that an hrtimer interrupt always sees a
consistent state of time and offsets.
ktime_get_update_offsets() allows us to get the current monotonic time
and update the per cpu hrtimer base offsets from hrtimer_interrupt()
to capture a consistent state of monotonic time and the offsets. The
function replaces the existing ktime_get() calls in hrtimer_interrupt().
The overhead of the new function vs. ktime_get() is minimal as it just
adds two store operations.
This ensures that any changes to realtime or boottime offsets are
noticed and stored into the per-cpu hrtimer base structures, prior to
any hrtimer expiration and guarantees that timers are not expired early.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-8-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
---
kernel/hrtimer.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 8fc6533..957869f 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -657,6 +657,14 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
return 0;
}
+static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
+{
+ ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
+ ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
+
+ return ktime_get_update_offsets(offs_real, offs_boot);
+}
+
/*
* Retrigger next event is called after clock was set
*
@@ -665,22 +673,12 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
static void retrigger_next_event(void *arg)
{
struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
- struct timespec realtime_offset, xtim, wtm, sleep;
if (!hrtimer_hres_active())
return;
- /* Optimized out for !HIGH_RES */
- get_xtime_and_monotonic_and_sleep_offset(&xtim, &wtm, &sleep);
- set_normalized_timespec(&realtime_offset, -wtm.tv_sec, -wtm.tv_nsec);
-
- /* Adjust CLOCK_REALTIME offset */
raw_spin_lock(&base->lock);
- base->clock_base[HRTIMER_BASE_REALTIME].offset =
- timespec_to_ktime(realtime_offset);
- base->clock_base[HRTIMER_BASE_BOOTTIME].offset =
- timespec_to_ktime(sleep);
-
+ hrtimer_update_base(base);
hrtimer_force_reprogram(base, 0);
raw_spin_unlock(&base->lock);
}
@@ -710,7 +708,6 @@ static int hrtimer_switch_to_hres(void)
base->clock_base[i].resolution = KTIME_HIGH_RES;
tick_setup_sched_timer();
-
/* "Retrigger" the interrupt to get things going */
retrigger_next_event(NULL);
local_irq_restore(flags);
@@ -1264,7 +1261,7 @@ void hrtimer_interrupt(struct clock_event_device *dev)
dev->next_event.tv64 = KTIME_MAX;
raw_spin_lock(&cpu_base->lock);
- entry_time = now = ktime_get();
+ entry_time = now = hrtimer_update_base(cpu_base);
retry:
expires_next.tv64 = KTIME_MAX;
/*
@@ -1342,9 +1339,12 @@ retry:
* We need to prevent that we loop forever in the hrtimer
* interrupt routine. We give it 3 attempts to avoid
* overreacting on some spurious event.
+ *
+ * Acquire base lock for updating the offsets and retrieving
+ * the current time.
*/
raw_spin_lock(&cpu_base->lock);
- now = ktime_get();
+ now = hrtimer_update_base(cpu_base);
cpu_base->nr_retries++;
if (++retries < 3)
goto retry;
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* [PATCH 11/11] 3.0.x: timekeeping: Add missing update call in timekeeping_resume()
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (9 preceding siblings ...)
2012-07-17 17:33 ` [PATCH 10/11] 3.0.x: hrtimer: Update hrtimer base offsets each hrtimer_interrupt John Stultz
@ 2012-07-17 17:33 ` John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Add missing update call in timekeeping_resume()" has been added to the 3.0-stable tree gregkh
2012-07-17 17:57 ` [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue Willy Tarreau
2012-07-17 22:50 ` Greg KH
12 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 17:33 UTC (permalink / raw)
To: stable
Cc: Thomas Gleixner, LKML, Linux PM list, John Stultz, Ingo Molnar,
Peter Zijlstra, Prarit Bhargava, Linus Torvalds
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of 3e997130bd2e8c6f5aaa49d6e3161d4d29b43ab0
The leap second rework unearthed another issue of inconsistent data.
On timekeeping_resume() the timekeeper data is updated, but nothing
calls timekeeping_update(), so now the update code in the timer
interrupt sees stale values.
This has been the case before those changes, but then the timer
interrupt was using stale data as well so this went unnoticed for quite
some time.
Add the missing update call, so all the data is consistent everywhere.
Reported-by: Andreas Schwab <schwab@linux-m68k.org>
Reported-and-tested-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Reported-and-tested-by: Martin Steigerwald <Martin@lichtvoll.de>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: Linux PM list <linux-pm@vger.kernel.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
---
kernel/time/timekeeping.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index f0c7565..678ae31 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -693,6 +693,7 @@ static void timekeeping_resume(void)
timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
timekeeper.ntp_error = 0;
timekeeping_suspended = 0;
+ timekeeping_update(false);
write_sequnlock_irqrestore(&xtime_lock, flags);
touch_softlockup_watchdog();
--
1.7.9.5
^ permalink raw reply related [flat|nested] 33+ messages in thread
* Re: [PATCH 04/11] 3.0.x: time: Move common updates to a function
2012-07-17 17:33 ` [PATCH 04/11] 3.0.x: time: Move common updates to a function John Stultz
@ 2012-07-17 17:49 ` Jonathan Nieder
2012-07-17 22:50 ` Patch "time: Move common updates to a function" has been added to the 3.0-stable tree gregkh
1 sibling, 0 replies; 33+ messages in thread
From: Jonathan Nieder @ 2012-07-17 17:49 UTC (permalink / raw)
To: John Stultz
Cc: stable, Thomas Gleixner, Eric Dumazet, Richard Cochran,
Prarit Bhargava, Linux Kernel, John Stultz
John Stultz wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> This is a backport of cc06268c6a87db156af2daed6e96a936b955cc82
>
> While not a bugfix itself, it allows following fixes to backport
> in a more straightforward manner.
Nicely done; thank you.
^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (10 preceding siblings ...)
2012-07-17 17:33 ` [PATCH 11/11] 3.0.x: timekeeping: Add missing update call in timekeeping_resume() John Stultz
@ 2012-07-17 17:57 ` Willy Tarreau
2012-07-17 18:15 ` John Stultz
2012-07-17 22:50 ` Greg KH
12 siblings, 1 reply; 33+ messages in thread
From: Willy Tarreau @ 2012-07-17 17:57 UTC (permalink / raw)
To: John Stultz; +Cc: stable, Prarit Bhargava, Thomas Gleixner, Linux Kernel
Hi John,
On Tue, Jul 17, 2012 at 01:33:47PM -0400, John Stultz wrote:
> Here is backport of the leapsecond fixes to 3.0-stable. These are less
> straight forward, and should get closer review.
>
> This patch set addresses two issues:
>
> 1) Deadlock leapsecond issue that a few reports described.
>
> I spent some time over the weekend trying to find a way to reproduce
> the hard-hang issue some folks were reporting after the leapsecond.
> Initially I didn't think the 6b43ae8a619d17 leap-second hrimter livelock
> patch needed to be backported since, I assumed it required the ntp_lock
> split for it to be triggered, but looking again I found that the same
> issue could occur prior to splitting out the ntp_lock. So I've backported
> that fix (and its follow-on fixups) as well as created a test case
> to reproduce the hard-hang deadlock.
>
>
> 2) Early hrtimer/futex expiration issue that was more widely observed
>
> This is the load-spike issue that a number of folks saw that did not
> hard hang most boxes (although some reports did show nmi-watchdogs
> triggering due to sudden spinning in tight loops).
>
> I've booted and tested this entire patchset on two boxes and run through a
> number of leapsecond related stress tests. However, additional testing and
> review would be appreciated.
>
> The original commits backported in this set are:
>
> Deadlock issue fixes:
> ---------------------
> 6b43ae8a619d17c4935c3320d2ef9e92bdeed05d ntp: Fix leap-second hrtimer livelock
> dd48d708ff3e917f6d6b6c2b696c3f18c019feed ntp: Correct TAI offset during leap second
> fad0c66c4bb836d57a5f125ecd38bed653ca863a timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond
>
> Helper change: (allows the following fixes to backport more easily):
> --------------------------------------------------------------------
> cc06268c6a87db156af2daed6e96a936b955cc82 time: Move common updates to a function
>
> Hrtimer early-expiration issue fixes:
> -------------------------------
> f55a6faa384304c89cfef162768e88374d3312cb hrtimer: Provide clock_was_set_delayed()
> 4873fa070ae84a4115f0b3c9dfabc224f1bc7c51 timekeeping: Fix leapsecond triggered load spike issue
> 5b9fe759a678e05be4937ddf03d50e950207c1c0 timekeeping: Maintain ktime_t based offsets for hrtimers
> 196951e91262fccda81147d2bcf7fdab08668b40 hrtimers: Move lock held region in hrtimer_interrupt()
> f6c06abfb3972ad4914cef57d8348fcb2932bc3b timekeeping: Provide hrtimer update function
> 5baefd6d84163443215f4a99f6a20f054ef11236 hrtimer: Update hrtimer base offsets each hrtimer_interrupt
> 3e997130bd2e8c6f5aaa49d6e3161d4d29b43ab0 timekeeping: Add missing update call in timekeeping_resume()
>
>
> I've already done backports to all the stable kernels to 2.6.32, and
> will send out the rest soon.
That's very much appreciated, thank you! Do not hesitate to send me
your reproducers, I'll happily run some tests.
Best regards,
Willy
^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
2012-07-17 17:57 ` [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue Willy Tarreau
@ 2012-07-17 18:15 ` John Stultz
2012-07-17 18:20 ` John Stultz
2012-07-17 19:05 ` Willy Tarreau
0 siblings, 2 replies; 33+ messages in thread
From: John Stultz @ 2012-07-17 18:15 UTC (permalink / raw)
To: Willy Tarreau; +Cc: stable, Prarit Bhargava, Thomas Gleixner, Linux Kernel
[-- Attachment #1: Type: text/plain, Size: 893 bytes --]
On 07/17/2012 10:57 AM, Willy Tarreau wrote:
> Hi John,
>
> On Tue, Jul 17, 2012 at 01:33:47PM -0400, John Stultz wrote:
>> I've already done backports to all the stable kernels to 2.6.32, and
>> will send out the rest soon.
> That's very much appreciated, thank you! Do not hesitate to send me
> your reproducers, I'll happily run some tests.
Attached are two tests. One is general exerciser of the leapsecond code
(leap-a-day) which also notes if it sees the hrtimer/futuex early
expiration issue, and the other is a much faster (almost immediate)
reproducer for the leapsecond deadlock (leapcrash).
The leapcrash test will likely wedge unpatched systems in hardirq
context, and has caused lost (dirty) data in my testing, so BEWARE!
RUN AT YOUR OWN RISK!
And of course, the leap-a-day has the same potential, but doesn't tickle
the deadlock issue as aggressively.
thanks
-john
[-- Attachment #2: leap-a-day.c --]
[-- Type: text/x-csrc, Size: 5540 bytes --]
/* Leap second stress test
* by: john stultz (johnstul@us.ibm.com)
* (C) Copyright IBM 2012
* Licensed under the GPLv2
*
* This test signals the kernel to insert a leap second
* every day at midnight GMT. This allows for stessing the
* kernel's leap-second behavior, as well as how well applications
* handle the leap-second discontinuity.
*
* Usage: leap-a-day [-s]
*
* Options:
* -s: Each iteration, set the date to 10 seconds before midnight GMT.
* This speeds up the number of leapsecond transitions tested,
* but because it calls settimeofday frequently, advancing the
* time by 24 hours every ~16 seconds, it may cause application
* disruption.
*
* Other notes: Disabling NTP prior to running this is advised, as the two
* may conflict in thier commands to the kernel.
*
* To build:
* $ gcc leap-a-day.c -o leap-a-day -lrt
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <string.h>
#include <signal.h>
#define NSEC_PER_SEC 1000000000ULL
/* returns 1 if a <= b, 0 otherwise */
static inline int in_order(struct timespec a, struct timespec b)
{
if(a.tv_sec < b.tv_sec)
return 1;
if(a.tv_sec > b.tv_sec)
return 0;
if(a.tv_nsec > b.tv_nsec)
return 0;
return 1;
}
struct timespec timespec_add(struct timespec ts, unsigned long long ns)
{
ts.tv_nsec += ns;
while(ts.tv_nsec >= NSEC_PER_SEC) {
ts.tv_nsec -= NSEC_PER_SEC;
ts.tv_sec++;
}
return ts;
}
char* time_state_str(int state)
{
switch (state) {
case TIME_OK: return "TIME_OK";
case TIME_INS: return "TIME_INS";
case TIME_DEL: return "TIME_DEL";
case TIME_OOP: return "TIME_OOP";
case TIME_WAIT: return "TIME_WAIT";
case TIME_BAD: return "TIME_BAD";
}
return "ERROR";
}
/* clear NTP time_status & time_state */
void clear_time_state(void)
{
struct timex tx;
int ret;
/*
* XXX - The fact we have to call this twice seems
* to point to a slight issue in the kernel's ntp state
* managment. Needs to be investigated further.
*/
tx.modes = ADJ_STATUS;
tx.status = STA_PLL;
ret = adjtimex(&tx);
tx.modes = ADJ_STATUS;
tx.status = 0;
ret = adjtimex(&tx);
}
/* Make sure we cleanup on ctrl-c */
void handler(int unused)
{
clear_time_state();
exit(0);
}
/* Test for known hrtimer failure */
void test_hrtimer_failure(void)
{
struct timespec now, target;
clock_gettime(CLOCK_REALTIME, &now);
target = timespec_add(now, NSEC_PER_SEC/2);
clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &target, NULL);
clock_gettime(CLOCK_REALTIME, &now);
if (!in_order(target, now)) {
printf("ERROR: hrtimer early expiration failure observed.\n");
}
}
int main(int argc, char** argv)
{
int settime = 0;
int insert = 1;
signal(SIGINT, handler);
signal(SIGKILL, handler);
printf("This runs continuously. Press ctrl-c to stop\n");
/* Process arguments */
if (argc > 1) {
if (!strncmp(argv[1], "-s", 2)) {
printf("Setting time to speed up testing\n");
settime = 1;
} else {
printf("Usage: %s [-s]\n", argv[0]);
printf(" -s: Set time to right before leap second each iteration\n");
}
}
printf("\n");
while (1) {
int ret;
struct timespec ts;
struct timex tx;
time_t now, next_leap;
/* Get the current time */
clock_gettime(CLOCK_REALTIME, &ts);
/* Calculate the next possible leap second 23:59:60 GMT */
next_leap = ts.tv_sec;
next_leap += 86400 - (next_leap % 86400);
if (settime) {
struct timeval tv;
tv.tv_sec = next_leap - 10;
tv.tv_usec = 0;
settimeofday(&tv, NULL);
printf("Setting time to %s", ctime(&tv.tv_sec));
}
/* Reset NTP time state */
clear_time_state();
/* Set the leap second insert flag */
tx.modes = ADJ_STATUS;
if (insert)
tx.status = STA_INS;
else
tx.status = STA_DEL;
ret = adjtimex(&tx);
if (ret < 0 ) {
printf("Error: Problem setting STA_INS/STA_DEL!: %s\n",
time_state_str(ret));
return -1;
}
/* Validate STA_INS was set */
ret = adjtimex(&tx);
if (tx.status != STA_INS && tx.status != STA_DEL) {
printf("Error: STA_INS/STA_DEL not set!: %s\n",
time_state_str(ret));
return -1;
}
printf("Scheduling leap second for %s", ctime(&next_leap));
/* Wake up 3 seconds before leap */
ts.tv_sec = next_leap - 3;
ts.tv_nsec = 0;
while(clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &ts, NULL))
printf("Something woke us up, returning to sleep\n");
/* Validate STA_INS is still set */
ret = adjtimex(&tx);
if (tx.status != STA_INS && tx.status != STA_DEL) {
printf("Something cleared STA_INS/STA_DEL, setting it again.\n");
tx.modes = ADJ_STATUS;
if (insert)
tx.status = STA_INS;
else
tx.status = STA_DEL;
ret = adjtimex(&tx);
}
/* Check adjtimex output every half second */
now = tx.time.tv_sec;
while (now < next_leap+2) {
char buf[26];
ret = adjtimex(&tx);
ctime_r(&tx.time.tv_sec, buf);
buf[strlen(buf)-1] = 0; /*remove trailing\n */
printf("%s + %6ld us\t%s\n",
buf,
tx.time.tv_usec,
time_state_str(ret));
now = tx.time.tv_sec;
/* Sleep for another half second */
ts.tv_sec = 0;
ts.tv_nsec = NSEC_PER_SEC/2;
clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL);
}
/* Switch to using other mode */
insert = !insert;
/* Note if kernel has known hrtimer failure */
test_hrtimer_failure();
printf("Leap complete\n\n");
}
clear_time_state();
return 0;
}
[-- Attachment #3: leapcrash.c --]
[-- Type: text/x-csrc, Size: 1928 bytes --]
/* Demo leapsecond deadlock
* by: john stultz (johnstul@us.ibm.com)
* (C) Copyright IBM 2012
* Licensed under the GPL
*
* This test demonstrates leapsecond deadlock that is possibe
* on kernels from 2.6.26 to 3.3.
*
* WARNING: THIS WILL LIKELY HARDHANG SYSTEMS AND MAY LOSE DATA
* RUN AT YOUR OWN RISK!
* To build:
* $ gcc leapcrash.c -o leapcrash -lrt
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <string.h>
#include <signal.h>
/* clear NTP time_status & time_state */
void clear_time_state(void)
{
struct timex tx;
int ret;
/*
* XXX - The fact we have to call this twice seems
* to point to a slight issue in the kernel's ntp state
* managment. Needs to be investigated further.
*/
tx.modes = ADJ_STATUS;
tx.status = STA_PLL;
ret = adjtimex(&tx);
tx.modes = ADJ_STATUS;
tx.status = 0;
ret = adjtimex(&tx);
}
/* Make sure we cleanup on ctrl-c */
void handler(int unused)
{
clear_time_state();
exit(0);
}
int main(void)
{
struct timex tx;
struct timespec ts;
time_t next_leap;
int count =0;
setbuf(stdout, NULL);
signal(SIGINT, handler);
signal(SIGKILL, handler);
printf("This runs continuously. Press ctrl-c to stop\n");
clear_time_state();
/* Get the current time */
clock_gettime(CLOCK_REALTIME, &ts);
/* Calculate the next possible leap second 23:59:60 GMT */
next_leap = ts.tv_sec;
next_leap += 86400 - (next_leap % 86400);
while (1) {
struct timeval tv;
/* set the time to 2 seconds before the leap */
tv.tv_sec = next_leap - 2;
tv.tv_usec = 0;
settimeofday(&tv, NULL);
adjtimex(&tx);
/* hammer on adjtime w/ STA_INS */
while (tx.time.tv_sec < next_leap + 1) {
/* Set the leap second insert flag */
tx.modes = ADJ_STATUS;
tx.status = STA_INS;
adjtimex(&tx);
}
clear_time_state();
printf(".");
}
return 0;
}
^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
2012-07-17 18:15 ` John Stultz
@ 2012-07-17 18:20 ` John Stultz
2012-07-17 18:26 ` Jonathan Nieder
2012-07-17 19:05 ` Willy Tarreau
1 sibling, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 18:20 UTC (permalink / raw)
To: Willy Tarreau; +Cc: stable, Prarit Bhargava, Thomas Gleixner, Linux Kernel
On 07/17/2012 11:15 AM, John Stultz wrote:
> On 07/17/2012 10:57 AM, Willy Tarreau wrote:
>> Hi John,
>>
>> On Tue, Jul 17, 2012 at 01:33:47PM -0400, John Stultz wrote:
>>> I've already done backports to all the stable kernels to 2.6.32, and
>>> will send out the rest soon.
>> That's very much appreciated, thank you! Do not hesitate to send me
>> your reproducers, I'll happily run some tests.
>
> Attached are two tests. One is general exerciser of the leapsecond
> code (leap-a-day) which also notes if it sees the hrtimer/futuex early
> expiration issue, and the other is a much faster (almost immediate)
> reproducer for the leapsecond deadlock (leapcrash).
>
> The leapcrash test will likely wedge unpatched systems in hardirq
> context, and has caused lost (dirty) data in my testing, so BEWARE!
> RUN AT YOUR OWN RISK!
>
> And of course, the leap-a-day has the same potential, but doesn't
> tickle the deadlock issue as aggressively.
As a tangent, I'm looking to try to get these tests integrated with a
testing suite that developers, distros and other testing organizations
run regularly. I'm aware of LTP, however last I looked at it, it seems
to have become a bit messy, being somewhat of a catch all, and in casual
asking around not too many folks I know regularly use it (Is that no
longer the case?).
Are there any other test suites that folks would recommend I look into
for merging these (and other time related) tests?
thanks
-john
^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
2012-07-17 18:20 ` John Stultz
@ 2012-07-17 18:26 ` Jonathan Nieder
2012-07-17 19:04 ` John Stultz
0 siblings, 1 reply; 33+ messages in thread
From: Jonathan Nieder @ 2012-07-17 18:26 UTC (permalink / raw)
To: John Stultz
Cc: Willy Tarreau, stable, Prarit Bhargava, Thomas Gleixner, Linux Kernel
John Stultz wrote:
> Are there any other test suites that folks would recommend I look
> into for merging these (and other time related) tests?
Would it be possible to put them in the kernel tree somewhere, for
example under tools/testing/?
Thanks,
Jonathan
^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
2012-07-17 18:26 ` Jonathan Nieder
@ 2012-07-17 19:04 ` John Stultz
2012-07-17 19:14 ` Jonathan Nieder
0 siblings, 1 reply; 33+ messages in thread
From: John Stultz @ 2012-07-17 19:04 UTC (permalink / raw)
To: Jonathan Nieder
Cc: Willy Tarreau, stable, Prarit Bhargava, Thomas Gleixner, Linux Kernel
On 07/17/2012 11:26 AM, Jonathan Nieder wrote:
> John Stultz wrote:
>
>> Are there any other test suites that folks would recommend I look
>> into for merging these (and other time related) tests?
> Would it be possible to put them in the kernel tree somewhere, for
> example under tools/testing/?
Huh. I guess its possible. However I'd like to avoid starting
yet-another-testing-framework.
The idea of keeping kernel tests close to the code could be nice since
it might avoid the bit-rot many testing suites get where bad tests start
failing and no one cares enough or has the context to sort out fixing
false positives.
But looking at the ltp project page, it seems there have been some good
cleanups in fixing known failures since last I looked (4 or so years
back). So it might be LTP is the proper place for this.
thanks
-john
^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
2012-07-17 18:15 ` John Stultz
2012-07-17 18:20 ` John Stultz
@ 2012-07-17 19:05 ` Willy Tarreau
1 sibling, 0 replies; 33+ messages in thread
From: Willy Tarreau @ 2012-07-17 19:05 UTC (permalink / raw)
To: John Stultz; +Cc: stable, Prarit Bhargava, Thomas Gleixner, Linux Kernel
On Tue, Jul 17, 2012 at 11:15:30AM -0700, John Stultz wrote:
> Attached are two tests. One is general exerciser of the leapsecond code
> (leap-a-day) which also notes if it sees the hrtimer/futuex early
> expiration issue, and the other is a much faster (almost immediate)
> reproducer for the leapsecond deadlock (leapcrash).
>
> The leapcrash test will likely wedge unpatched systems in hardirq
> context, and has caused lost (dirty) data in my testing, so BEWARE!
> RUN AT YOUR OWN RISK!
Thank you, and nice note for the big warning above. I have some diskless
machines which don't risk anything, I will test there first :-)
Cheers,
Willy
^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
2012-07-17 19:04 ` John Stultz
@ 2012-07-17 19:14 ` Jonathan Nieder
2012-07-17 19:18 ` John Stultz
0 siblings, 1 reply; 33+ messages in thread
From: Jonathan Nieder @ 2012-07-17 19:14 UTC (permalink / raw)
To: John Stultz
Cc: Willy Tarreau, stable, Prarit Bhargava, Thomas Gleixner, Linux Kernel
John Stultz wrote:
> On 07/17/2012 11:26 AM, Jonathan Nieder wrote:
>> Would it be possible to put them in the kernel tree somewhere, for
>> example under tools/testing/?
>
> Huh. I guess its possible. However I'd like to avoid starting
> yet-another-testing-framework.
Too late: http://thread.gmane.org/gmane.linux.kernel/1223571/focus=1226221
:)
Jonathan
^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
2012-07-17 19:14 ` Jonathan Nieder
@ 2012-07-17 19:18 ` John Stultz
0 siblings, 0 replies; 33+ messages in thread
From: John Stultz @ 2012-07-17 19:18 UTC (permalink / raw)
To: Jonathan Nieder
Cc: Willy Tarreau, stable, Prarit Bhargava, Thomas Gleixner, Linux Kernel
On 07/17/2012 12:14 PM, Jonathan Nieder wrote:
> John Stultz wrote:
>> On 07/17/2012 11:26 AM, Jonathan Nieder wrote:
>>> Would it be possible to put them in the kernel tree somewhere, for
>>> example under tools/testing/?
>> Huh. I guess its possible. However I'd like to avoid starting
>> yet-another-testing-framework.
> Too late: http://thread.gmane.org/gmane.linux.kernel/1223571/focus=1226221
:)
Although Andrew's comment: "All these features are Linux-specific.
Standard interface features (eg POSIX) are and should be tested via
other externally-maintained test suites." suggests my time tests should
go elsewhere.
thanks
-john
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "hrtimer: Provide clock_was_set_delayed()" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 05/11] 3.0.x: hrtimer: Provide clock_was_set_delayed() John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, a.p.zijlstra, gregkh, jengelh, linux-kernel, mingo,
prarit, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
hrtimer: Provide clock_was_set_delayed()
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hrtimer-provide-clock_was_set_delayed.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:25:04 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:52 -0400
Subject: hrtimer: Provide clock_was_set_delayed()
To: stable@vger.kernel.org
Cc: John Stultz <johnstul@us.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Prarit Bhargava <prarit@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Message-ID: <1342546438-17534-6-git-send-email-johnstul@us.ibm.com>
From: John Stultz <johnstul@us.ibm.com>
This is a backport of f55a6faa384304c89cfef162768e88374d3312cb
clock_was_set() cannot be called from hard interrupt context because
it calls on_each_cpu().
For fixing the widely reported leap seconds issue it is necessary to
call it from hard interrupt context, i.e. the timer tick code, which
does the timekeeping updates.
Provide a new function which denotes it in the hrtimer cpu base
structure of the cpu on which it is called and raise the hrtimer
softirq. We then execute the clock_was_set() notificiation from
softirq context in run_hrtimer_softirq(). The hrtimer softirq is
rarely used, so polling the flag there is not a performance issue.
[ tglx: Made it depend on CONFIG_HIGH_RES_TIMERS. We really should get
rid of all this ifdeffery ASAP ]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reported-by: Jan Engelhardt <jengelh@inai.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1341960205-56738-2-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/hrtimer.h | 9 ++++++++-
kernel/hrtimer.c | 20 ++++++++++++++++++++
2 files changed, 28 insertions(+), 1 deletion(-)
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -165,6 +165,7 @@ enum hrtimer_base_type {
* @lock: lock protecting the base and associated clock bases
* and timers
* @active_bases: Bitfield to mark bases with active timers
+ * @clock_was_set: Indicates that clock was set from irq context.
* @expires_next: absolute time of the next event which was scheduled
* via clock_set_next_event()
* @hres_active: State of high resolution mode
@@ -177,7 +178,8 @@ enum hrtimer_base_type {
*/
struct hrtimer_cpu_base {
raw_spinlock_t lock;
- unsigned long active_bases;
+ unsigned int active_bases;
+ unsigned int clock_was_set;
#ifdef CONFIG_HIGH_RES_TIMERS
ktime_t expires_next;
int hres_active;
@@ -286,6 +288,8 @@ extern void hrtimer_peek_ahead_timers(vo
# define MONOTONIC_RES_NSEC HIGH_RES_NSEC
# define KTIME_MONOTONIC_RES KTIME_HIGH_RES
+extern void clock_was_set_delayed(void);
+
#else
# define MONOTONIC_RES_NSEC LOW_RES_NSEC
@@ -306,6 +310,9 @@ static inline int hrtimer_is_hres_active
{
return 0;
}
+
+static inline void clock_was_set_delayed(void) { }
+
#endif
extern void clock_was_set(void);
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -717,6 +717,19 @@ static int hrtimer_switch_to_hres(void)
return 1;
}
+/*
+ * Called from timekeeping code to reprogramm the hrtimer interrupt
+ * device. If called from the timer interrupt context we defer it to
+ * softirq context.
+ */
+void clock_was_set_delayed(void)
+{
+ struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+
+ cpu_base->clock_was_set = 1;
+ __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+}
+
#else
static inline int hrtimer_hres_active(void) { return 0; }
@@ -1395,6 +1408,13 @@ void hrtimer_peek_ahead_timers(void)
static void run_hrtimer_softirq(struct softirq_action *h)
{
+ struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+
+ if (cpu_base->clock_was_set) {
+ cpu_base->clock_was_set = 0;
+ clock_was_set();
+ }
+
hrtimer_peek_ahead_timers();
}
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "hrtimers: Move lock held region in hrtimer_interrupt()" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 08/11] 3.0.x: hrtimers: Move lock held region in hrtimer_interrupt() John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, a.p.zijlstra, gregkh, linux-kernel, mingo, prarit, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
hrtimers: Move lock held region in hrtimer_interrupt()
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:26:26 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:55 -0400
Subject: hrtimers: Move lock held region in hrtimer_interrupt()
To: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>, John Stultz <johnstul@us.ibm.com>, Prarit Bhargava <prarit@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Message-ID: <1342546438-17534-9-git-send-email-johnstul@us.ibm.com>
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of 196951e91262fccda81147d2bcf7fdab08668b40
We need to update the base offsets from this code and we need to do
that under base->lock. Move the lock held region around the
ktime_get() calls. The ktime_get() calls are going to be replaced with
a function which gets the time and the offsets atomically.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/1341960205-56738-6-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/hrtimer.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1263,11 +1263,10 @@ void hrtimer_interrupt(struct clock_even
cpu_base->nr_events++;
dev->next_event.tv64 = KTIME_MAX;
+ raw_spin_lock(&cpu_base->lock);
entry_time = now = ktime_get();
retry:
expires_next.tv64 = KTIME_MAX;
-
- raw_spin_lock(&cpu_base->lock);
/*
* We set expires_next to KTIME_MAX here with cpu_base->lock
* held to prevent that a timer is enqueued in our queue via
@@ -1344,6 +1343,7 @@ retry:
* interrupt routine. We give it 3 attempts to avoid
* overreacting on some spurious event.
*/
+ raw_spin_lock(&cpu_base->lock);
now = ktime_get();
cpu_base->nr_retries++;
if (++retries < 3)
@@ -1356,6 +1356,7 @@ retry:
*/
cpu_base->nr_hangs++;
cpu_base->hang_detected = 1;
+ raw_spin_unlock(&cpu_base->lock);
delta = ktime_sub(now, entry_time);
if (delta.tv64 > cpu_base->max_hang_time.tv64)
cpu_base->max_hang_time = delta;
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "hrtimer: Update hrtimer base offsets each hrtimer_interrupt" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 10/11] 3.0.x: hrtimer: Update hrtimer base offsets each hrtimer_interrupt John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, a.p.zijlstra, gregkh, linux-kernel, mingo, prarit, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
hrtimer: Update hrtimer base offsets each hrtimer_interrupt
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:26:57 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:57 -0400
Subject: hrtimer: Update hrtimer base offsets each hrtimer_interrupt
To: stable@vger.kernel.org
Cc: John Stultz <johnstul@us.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Prarit Bhargava <prarit@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Message-ID: <1342546438-17534-11-git-send-email-johnstul@us.ibm.com>
From: John Stultz <johnstul@us.ibm.com>
This is a backport of 5baefd6d84163443215f4a99f6a20f054ef11236
The update of the hrtimer base offsets on all cpus cannot be made
atomically from the timekeeper.lock held and interrupt disabled region
as smp function calls are not allowed there.
clock_was_set(), which enforces the update on all cpus, is called
either from preemptible process context in case of do_settimeofday()
or from the softirq context when the offset modification happened in
the timer interrupt itself due to a leap second.
In both cases there is a race window for an hrtimer interrupt between
dropping timekeeper lock, enabling interrupts and clock_was_set()
issuing the updates. Any interrupt which arrives in that window will
see the new time but operate on stale offsets.
So we need to make sure that an hrtimer interrupt always sees a
consistent state of time and offsets.
ktime_get_update_offsets() allows us to get the current monotonic time
and update the per cpu hrtimer base offsets from hrtimer_interrupt()
to capture a consistent state of monotonic time and the offsets. The
function replaces the existing ktime_get() calls in hrtimer_interrupt().
The overhead of the new function vs. ktime_get() is minimal as it just
adds two store operations.
This ensures that any changes to realtime or boottime offsets are
noticed and stored into the per-cpu hrtimer base structures, prior to
any hrtimer expiration and guarantees that timers are not expired early.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1341960205-56738-8-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/hrtimer.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -657,6 +657,14 @@ static inline int hrtimer_enqueue_reprog
return 0;
}
+static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
+{
+ ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
+ ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
+
+ return ktime_get_update_offsets(offs_real, offs_boot);
+}
+
/*
* Retrigger next event is called after clock was set
*
@@ -665,22 +673,12 @@ static inline int hrtimer_enqueue_reprog
static void retrigger_next_event(void *arg)
{
struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
- struct timespec realtime_offset, xtim, wtm, sleep;
if (!hrtimer_hres_active())
return;
- /* Optimized out for !HIGH_RES */
- get_xtime_and_monotonic_and_sleep_offset(&xtim, &wtm, &sleep);
- set_normalized_timespec(&realtime_offset, -wtm.tv_sec, -wtm.tv_nsec);
-
- /* Adjust CLOCK_REALTIME offset */
raw_spin_lock(&base->lock);
- base->clock_base[HRTIMER_BASE_REALTIME].offset =
- timespec_to_ktime(realtime_offset);
- base->clock_base[HRTIMER_BASE_BOOTTIME].offset =
- timespec_to_ktime(sleep);
-
+ hrtimer_update_base(base);
hrtimer_force_reprogram(base, 0);
raw_spin_unlock(&base->lock);
}
@@ -710,7 +708,6 @@ static int hrtimer_switch_to_hres(void)
base->clock_base[i].resolution = KTIME_HIGH_RES;
tick_setup_sched_timer();
-
/* "Retrigger" the interrupt to get things going */
retrigger_next_event(NULL);
local_irq_restore(flags);
@@ -1264,7 +1261,7 @@ void hrtimer_interrupt(struct clock_even
dev->next_event.tv64 = KTIME_MAX;
raw_spin_lock(&cpu_base->lock);
- entry_time = now = ktime_get();
+ entry_time = now = hrtimer_update_base(cpu_base);
retry:
expires_next.tv64 = KTIME_MAX;
/*
@@ -1342,9 +1339,12 @@ retry:
* We need to prevent that we loop forever in the hrtimer
* interrupt routine. We give it 3 attempts to avoid
* overreacting on some spurious event.
+ *
+ * Acquire base lock for updating the offsets and retrieving
+ * the current time.
*/
raw_spin_lock(&cpu_base->lock);
- now = ktime_get();
+ now = hrtimer_update_base(cpu_base);
cpu_base->nr_retries++;
if (++retries < 3)
goto retry;
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "ntp: Correct TAI offset during leap second" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 02/11] 3.0.x: ntp: Correct TAI offset during leap second John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, gregkh, john.stultz, linux-kernel, prarit,
richardcochran, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
ntp: Correct TAI offset during leap second
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ntp-correct-tai-offset-during-leap-second.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:24:12 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:49 -0400
Subject: ntp: Correct TAI offset during leap second
To: stable@vger.kernel.org
Cc: Richard Cochran <richardcochran@gmail.com>, Prarit Bhargava <prarit@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Linux Kernel <linux-kernel@vger.kernel.org>, John Stultz <john.stultz@linaro.org>
Message-ID: <1342546438-17534-3-git-send-email-johnstul@us.ibm.com>
From: Richard Cochran <richardcochran@gmail.com>
This is a backport of dd48d708ff3e917f6d6b6c2b696c3f18c019feed
When repeating a UTC time value during a leap second (when the UTC
time should be 23:59:60), the TAI timescale should not stop. The kernel
NTP code increments the TAI offset one second too late. This patch fixes
the issue by incrementing the offset during the leap second itself.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/time/ntp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -378,6 +378,7 @@ int second_overflow(unsigned long secs)
if (secs % 86400 == 0) {
leap = -1;
time_state = TIME_OOP;
+ time_tai++;
printk(KERN_NOTICE
"Clock: inserting leap second 23:59:60 UTC\n");
}
@@ -392,7 +393,6 @@ int second_overflow(unsigned long secs)
}
break;
case TIME_OOP:
- time_tai++;
time_state = TIME_WAIT;
break;
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "timekeeping: Add missing update call in timekeeping_resume()" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 11/11] 3.0.x: timekeeping: Add missing update call in timekeeping_resume() John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, a.p.zijlstra, gregkh, linux-kernel, linux-pm, Martin,
mingo, prarit, rjw, schwab, tglx, torvalds
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
timekeeping: Add missing update call in timekeeping_resume()
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
timekeeping-add-missing-update-call-in-timekeeping_resume.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:27:16 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:58 -0400
Subject: timekeeping: Add missing update call in timekeeping_resume()
To: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>, LKML <linux-kernel@vger.kernel.org>, Linux PM list <linux-pm@vger.kernel.org>, John Stultz <johnstul@us.ibm.com>, Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Prarit Bhargava <prarit@redhat.com>, Linus Torvalds <torvalds@linux-foundation.org>
Message-ID: <1342546438-17534-12-git-send-email-johnstul@us.ibm.com>
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of 3e997130bd2e8c6f5aaa49d6e3161d4d29b43ab0
The leap second rework unearthed another issue of inconsistent data.
On timekeeping_resume() the timekeeper data is updated, but nothing
calls timekeeping_update(), so now the update code in the timer
interrupt sees stale values.
This has been the case before those changes, but then the timer
interrupt was using stale data as well so this went unnoticed for quite
some time.
Add the missing update call, so all the data is consistent everywhere.
Reported-by: Andreas Schwab <schwab@linux-m68k.org>
Reported-and-tested-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Reported-and-tested-by: Martin Steigerwald <Martin@lichtvoll.de>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/time/timekeeping.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -693,6 +693,7 @@ static void timekeeping_resume(void)
timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
timekeeper.ntp_error = 0;
timekeeping_suspended = 0;
+ timekeeping_update(false);
write_sequnlock_irqrestore(&xtime_lock, flags);
touch_softlockup_watchdog();
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "ntp: Fix leap-second hrtimer livelock" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 01/11] 3.0.x: ntp: Fix leap-second hrtimer livelock John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, gregkh, john.stultz, levinsasha928, linux-kernel, prarit, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
ntp: Fix leap-second hrtimer livelock
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ntp-fix-leap-second-hrtimer-livelock.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:23:32 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:48 -0400
Subject: ntp: Fix leap-second hrtimer livelock
To: stable@vger.kernel.org
Cc: John Stultz <john.stultz@linaro.org>, Sasha Levin <levinsasha928@gmail.com>, Thomas Gleixner <tglx@linutronix.de>, Prarit Bhargava <prarit@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Message-ID: <1342546438-17534-2-git-send-email-johnstul@us.ibm.com>
From: John Stultz <john.stultz@linaro.org>
This is a backport of 6b43ae8a619d17c4935c3320d2ef9e92bdeed05d
This should have been backported when it was commited, but I
mistook the problem as requiring the ntp_lock changes
that landed in 3.4 in order for it to occur.
Unfortunately the same issue can happen (with only one cpu)
as follows:
do_adjtimex()
write_seqlock_irq(&xtime_lock);
process_adjtimex_modes()
process_adj_status()
ntp_start_leap_timer()
hrtimer_start()
hrtimer_reprogram()
tick_program_event()
clockevents_program_event()
ktime_get()
seq = req_seqbegin(xtime_lock); [DEADLOCK]
This deadlock will no always occur, as it requires the
leap_timer to force a hrtimer_reprogram which only happens
if its set and there's no sooner timer to expire.
NOTE: This patch, being faithful to the original commit,
introduces a bug (we don't update wall_to_monotonic),
which will be resovled by backporting a following fix.
Original commit message below:
Since commit 7dffa3c673fbcf835cd7be80bb4aec8ad3f51168 the ntp
subsystem has used an hrtimer for triggering the leapsecond
adjustment. However, this can cause a potential livelock.
Thomas diagnosed this as the following pattern:
CPU 0 CPU 1
do_adjtimex()
spin_lock_irq(&ntp_lock);
process_adjtimex_modes(); timer_interrupt()
process_adj_status(); do_timer()
ntp_start_leap_timer(); write_lock(&xtime_lock);
hrtimer_start(); update_wall_time();
hrtimer_reprogram(); ntp_tick_length()
tick_program_event() spin_lock(&ntp_lock);
clockevents_program_event()
ktime_get()
seq = req_seqbegin(xtime_lock);
This patch tries to avoid the problem by reverting back to not using
an hrtimer to inject leapseconds, and instead we handle the leapsecond
processing in the second_overflow() function.
The downside to this change is that on systems that support highres
timers, the leap second processing will occur on a HZ tick boundary,
(ie: ~1-10ms, depending on HZ) after the leap second instead of
possibly sooner (~34us in my tests w/ x86_64 lapic).
This patch applies on top of tip/timers/core.
CC: Sasha Levin <levinsasha928@gmail.com>
CC: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Diagnoised-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/timex.h | 2
kernel/time/ntp.c | 122 +++++++++++++++-------------------------------
kernel/time/timekeeping.c | 18 ++----
3 files changed, 48 insertions(+), 94 deletions(-)
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -266,7 +266,7 @@ static inline int ntp_synced(void)
/* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */
extern u64 tick_length;
-extern void second_overflow(void);
+extern int second_overflow(unsigned long secs);
extern void update_ntp_one_tick(void);
extern int do_adjtimex(struct timex *);
extern void hardpps(const struct timespec *, const struct timespec *);
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -31,8 +31,6 @@ unsigned long tick_nsec;
u64 tick_length;
static u64 tick_length_base;
-static struct hrtimer leap_timer;
-
#define MAX_TICKADJ 500LL /* usecs */
#define MAX_TICKADJ_SCALED \
(((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
@@ -350,60 +348,60 @@ void ntp_clear(void)
}
/*
- * Leap second processing. If in leap-insert state at the end of the
- * day, the system clock is set back one second; if in leap-delete
- * state, the system clock is set ahead one second.
+ * this routine handles the overflow of the microsecond field
+ *
+ * The tricky bits of code to handle the accurate clock support
+ * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
+ * They were originally developed for SUN and DEC kernels.
+ * All the kudos should go to Dave for this stuff.
+ *
+ * Also handles leap second processing, and returns leap offset
*/
-static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
+int second_overflow(unsigned long secs)
{
- enum hrtimer_restart res = HRTIMER_NORESTART;
-
- write_seqlock(&xtime_lock);
+ int leap = 0;
+ s64 delta;
+ /*
+ * Leap second processing. If in leap-insert state at the end of the
+ * day, the system clock is set back one second; if in leap-delete
+ * state, the system clock is set ahead one second.
+ */
switch (time_state) {
case TIME_OK:
+ if (time_status & STA_INS)
+ time_state = TIME_INS;
+ else if (time_status & STA_DEL)
+ time_state = TIME_DEL;
break;
case TIME_INS:
- timekeeping_leap_insert(-1);
- time_state = TIME_OOP;
- printk(KERN_NOTICE
- "Clock: inserting leap second 23:59:60 UTC\n");
- hrtimer_add_expires_ns(&leap_timer, NSEC_PER_SEC);
- res = HRTIMER_RESTART;
+ if (secs % 86400 == 0) {
+ leap = -1;
+ time_state = TIME_OOP;
+ printk(KERN_NOTICE
+ "Clock: inserting leap second 23:59:60 UTC\n");
+ }
break;
case TIME_DEL:
- timekeeping_leap_insert(1);
- time_tai--;
- time_state = TIME_WAIT;
- printk(KERN_NOTICE
- "Clock: deleting leap second 23:59:59 UTC\n");
+ if ((secs + 1) % 86400 == 0) {
+ leap = 1;
+ time_tai--;
+ time_state = TIME_WAIT;
+ printk(KERN_NOTICE
+ "Clock: deleting leap second 23:59:59 UTC\n");
+ }
break;
case TIME_OOP:
time_tai++;
time_state = TIME_WAIT;
- /* fall through */
+ break;
+
case TIME_WAIT:
if (!(time_status & (STA_INS | STA_DEL)))
time_state = TIME_OK;
break;
}
- write_sequnlock(&xtime_lock);
-
- return res;
-}
-
-/*
- * this routine handles the overflow of the microsecond field
- *
- * The tricky bits of code to handle the accurate clock support
- * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
- * They were originally developed for SUN and DEC kernels.
- * All the kudos should go to Dave for this stuff.
- */
-void second_overflow(void)
-{
- s64 delta;
/* Bump the maxerror field */
time_maxerror += MAXFREQ / NSEC_PER_USEC;
@@ -423,23 +421,25 @@ void second_overflow(void)
pps_dec_valid();
if (!time_adjust)
- return;
+ goto out;
if (time_adjust > MAX_TICKADJ) {
time_adjust -= MAX_TICKADJ;
tick_length += MAX_TICKADJ_SCALED;
- return;
+ goto out;
}
if (time_adjust < -MAX_TICKADJ) {
time_adjust += MAX_TICKADJ;
tick_length -= MAX_TICKADJ_SCALED;
- return;
+ goto out;
}
tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
<< NTP_SCALE_SHIFT;
time_adjust = 0;
+out:
+ return leap;
}
#ifdef CONFIG_GENERIC_CMOS_UPDATE
@@ -501,27 +501,6 @@ static void notify_cmos_timer(void)
static inline void notify_cmos_timer(void) { }
#endif
-/*
- * Start the leap seconds timer:
- */
-static inline void ntp_start_leap_timer(struct timespec *ts)
-{
- long now = ts->tv_sec;
-
- if (time_status & STA_INS) {
- time_state = TIME_INS;
- now += 86400 - now % 86400;
- hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS);
-
- return;
- }
-
- if (time_status & STA_DEL) {
- time_state = TIME_DEL;
- now += 86400 - (now + 1) % 86400;
- hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS);
- }
-}
/*
* Propagate a new txc->status value into the NTP state:
@@ -546,22 +525,6 @@ static inline void process_adj_status(st
time_status &= STA_RONLY;
time_status |= txc->status & ~STA_RONLY;
- switch (time_state) {
- case TIME_OK:
- ntp_start_leap_timer(ts);
- break;
- case TIME_INS:
- case TIME_DEL:
- time_state = TIME_OK;
- ntp_start_leap_timer(ts);
- case TIME_WAIT:
- if (!(time_status & (STA_INS | STA_DEL)))
- time_state = TIME_OK;
- break;
- case TIME_OOP:
- hrtimer_restart(&leap_timer);
- break;
- }
}
/*
* Called with the xtime lock held, so we can access and modify
@@ -643,9 +606,6 @@ int do_adjtimex(struct timex *txc)
(txc->tick < 900000/USER_HZ ||
txc->tick > 1100000/USER_HZ))
return -EINVAL;
-
- if (txc->modes & ADJ_STATUS && time_state != TIME_OK)
- hrtimer_cancel(&leap_timer);
}
if (txc->modes & ADJ_SETOFFSET) {
@@ -967,6 +927,4 @@ __setup("ntp_tick_adj=", ntp_tick_adj_se
void __init ntp_init(void)
{
ntp_clear();
- hrtimer_init(&leap_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
- leap_timer.function = ntp_leap_second;
}
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -169,15 +169,6 @@ static struct timespec raw_time;
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
-/* must hold xtime_lock */
-void timekeeping_leap_insert(int leapsecond)
-{
- xtime.tv_sec += leapsecond;
- wall_to_monotonic.tv_sec -= leapsecond;
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
-}
-
/**
* timekeeping_forward_now - update clock to the current time
*
@@ -828,9 +819,11 @@ static cycle_t logarithmic_accumulation(
timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
while (timekeeper.xtime_nsec >= nsecps) {
+ int leap;
timekeeper.xtime_nsec -= nsecps;
xtime.tv_sec++;
- second_overflow();
+ leap = second_overflow(xtime.tv_sec);
+ xtime.tv_sec += leap;
}
/* Accumulate raw time */
@@ -936,9 +929,12 @@ static void update_wall_time(void)
* xtime.tv_nsec isn't larger then NSEC_PER_SEC
*/
if (unlikely(xtime.tv_nsec >= NSEC_PER_SEC)) {
+ int leap;
xtime.tv_nsec -= NSEC_PER_SEC;
xtime.tv_sec++;
- second_overflow();
+ leap = second_overflow(xtime.tv_sec);
+ xtime.tv_sec += leap;
+
}
/* check to see if there is a new clocksource to use */
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "timekeeping: Fix leapsecond triggered load spike issue" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 06/11] 3.0.x: timekeeping: Fix leapsecond triggered load spike issue John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, a.p.zijlstra, gregkh, jengelh, linux-kernel, mingo,
prarit, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
timekeeping: Fix leapsecond triggered load spike issue
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:25:50 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:53 -0400
Subject: timekeeping: Fix leapsecond triggered load spike issue
To: stable@vger.kernel.org
Cc: John Stultz <johnstul@us.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Prarit Bhargava <prarit@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Message-ID: <1342546438-17534-7-git-send-email-johnstul@us.ibm.com>
From: John Stultz <johnstul@us.ibm.com>
This is a backport of 4873fa070ae84a4115f0b3c9dfabc224f1bc7c51
The timekeeping code misses an update of the hrtimer subsystem after a
leap second happened. Due to that timers based on CLOCK_REALTIME are
either expiring a second early or late depending on whether a leap
second has been inserted or deleted until an operation is initiated
which causes that update. Unless the update happens by some other
means this discrepancy between the timekeeping and the hrtimer data
stays forever and timers are expired either early or late.
The reported immediate workaround - $ data -s "`date`" - is causing a
call to clock_was_set() which updates the hrtimer data structures.
See: http://www.sheeri.com/content/mysql-and-leap-second-high-cpu-and-fix
Add the missing clock_was_set() call to update_wall_time() in case of
a leap second event. The actual update is deferred to softirq context
as the necessary smp function call cannot be invoked from hard
interrupt context.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reported-by: Jan Engelhardt <jengelh@inai.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1341960205-56738-3-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/time/timekeeping.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -827,6 +827,8 @@ static cycle_t logarithmic_accumulation(
leap = second_overflow(xtime.tv_sec);
xtime.tv_sec += leap;
wall_to_monotonic.tv_sec -= leap;
+ if (leap)
+ clock_was_set_delayed();
}
/* Accumulate raw time */
@@ -938,6 +940,8 @@ static void update_wall_time(void)
leap = second_overflow(xtime.tv_sec);
xtime.tv_sec += leap;
wall_to_monotonic.tv_sec -= leap;
+ if (leap)
+ clock_was_set_delayed();
}
timekeeping_update(false);
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 03/11] 3.0.x: timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, gregkh, john.stultz, linux-kernel, prarit,
richardcochran, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:24:29 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:50 -0400
Subject: timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond
To: stable@vger.kernel.org
Cc: John Stultz <john.stultz@linaro.org>, Thomas Gleixner <tglx@linutronix.de>, Prarit Bhargava <prarit@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>, John Stultz <johnstul@us.ibm.com>
Message-ID: <1342546438-17534-4-git-send-email-johnstul@us.ibm.com>
From: John Stultz <john.stultz@linaro.org>
This is a backport of fad0c66c4bb836d57a5f125ecd38bed653ca863a
which resolves a bug the previous commit.
Commit 6b43ae8a61 (ntp: Fix leap-second hrtimer livelock) broke the
leapsecond update of CLOCK_MONOTONIC. The missing leapsecond update to
wall_to_monotonic causes discontinuities in CLOCK_MONOTONIC.
Adjust wall_to_monotonic when NTP inserted a leapsecond.
Reported-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Tested-by: Richard Cochran <richardcochran@gmail.com>
Link: http://lkml.kernel.org/r/1338400497-12420-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/time/timekeeping.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -824,6 +824,7 @@ static cycle_t logarithmic_accumulation(
xtime.tv_sec++;
leap = second_overflow(xtime.tv_sec);
xtime.tv_sec += leap;
+ wall_to_monotonic.tv_sec -= leap;
}
/* Accumulate raw time */
@@ -934,7 +935,7 @@ static void update_wall_time(void)
xtime.tv_sec++;
leap = second_overflow(xtime.tv_sec);
xtime.tv_sec += leap;
-
+ wall_to_monotonic.tv_sec -= leap;
}
/* check to see if there is a new clocksource to use */
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "timekeeping: Maintain ktime_t based offsets for hrtimers" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 07/11] 3.0.x: timekeeping: Maintain ktime_t based offsets for hrtimers John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, a.p.zijlstra, gregkh, linux-kernel, mingo, prarit, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
timekeeping: Maintain ktime_t based offsets for hrtimers
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:26:11 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:54 -0400
Subject: timekeeping: Maintain ktime_t based offsets for hrtimers
To: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>, John Stultz <johnstul@us.ibm.com>, Prarit Bhargava <prarit@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Message-ID: <1342546438-17534-8-git-send-email-johnstul@us.ibm.com>
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of 5b9fe759a678e05be4937ddf03d50e950207c1c0
We need to update the hrtimer clock offsets from the hrtimer interrupt
context. To avoid conversions from timespec to ktime_t maintain a
ktime_t based representation of those offsets in the timekeeper. This
puts the conversion overhead into the code which updates the
underlying offsets and provides fast accessible values in the hrtimer
interrupt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1341960205-56738-4-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/time/timekeeping.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -161,18 +161,34 @@ static struct timespec xtime __attribute
static struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
static struct timespec total_sleep_time;
+/* Offset clock monotonic -> clock realtime */
+static ktime_t offs_real;
+
+/* Offset clock monotonic -> clock boottime */
+static ktime_t offs_boot;
+
/*
* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
*/
static struct timespec raw_time;
/* must hold write on xtime_lock */
+static void update_rt_offset(void)
+{
+ struct timespec tmp, *wtm = &wall_to_monotonic;
+
+ set_normalized_timespec(&tmp, -wtm->tv_sec, -wtm->tv_nsec);
+ offs_real = timespec_to_ktime(tmp);
+}
+
+/* must hold write on xtime_lock */
static void timekeeping_update(bool clearntp)
{
if (clearntp) {
timekeeper.ntp_error = 0;
ntp_clear();
}
+ update_rt_offset();
update_vsyscall(&xtime, &wall_to_monotonic,
timekeeper.clock, timekeeper.mult);
}
@@ -587,6 +603,7 @@ void __init timekeeping_init(void)
}
set_normalized_timespec(&wall_to_monotonic,
-boot.tv_sec, -boot.tv_nsec);
+ update_rt_offset();
total_sleep_time.tv_sec = 0;
total_sleep_time.tv_nsec = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -595,6 +612,12 @@ void __init timekeeping_init(void)
/* time in seconds when suspend began */
static struct timespec timekeeping_suspend_time;
+static void update_sleep_time(struct timespec t)
+{
+ total_sleep_time = t;
+ offs_boot = timespec_to_ktime(t);
+}
+
/**
* __timekeeping_inject_sleeptime - Internal function to add sleep interval
* @delta: pointer to a timespec delta value
@@ -606,7 +629,7 @@ static void __timekeeping_inject_sleepti
{
xtime = timespec_add(xtime, *delta);
wall_to_monotonic = timespec_sub(wall_to_monotonic, *delta);
- total_sleep_time = timespec_add(total_sleep_time, *delta);
+ update_sleep_time(timespec_add(total_sleep_time, *delta));
}
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "timekeeping: Provide hrtimer update function" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 09/11] 3.0.x: timekeeping: Provide hrtimer update function John Stultz
@ 2012-07-17 22:49 ` gregkh
0 siblings, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:49 UTC (permalink / raw)
To: johnstul, a.p.zijlstra, gregkh, linux-kernel, mingo, prarit, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
timekeeping: Provide hrtimer update function
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
timekeeping-provide-hrtimer-update-function.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:26:41 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:56 -0400
Subject: timekeeping: Provide hrtimer update function
To: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>, John Stultz <johnstul@us.ibm.com>, Prarit Bhargava <prarit@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Message-ID: <1342546438-17534-10-git-send-email-johnstul@us.ibm.com>
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of f6c06abfb3972ad4914cef57d8348fcb2932bc3b
To finally fix the infamous leap second issue and other race windows
caused by functions which change the offsets between the various time
bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a
function which atomically gets the current monotonic time and updates
the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic
overhead. The previous patch which provides ktime_t offsets allows us
to make this function almost as cheap as ktime_get() which is going to
be replaced in hrtimer_interrupt().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/hrtimer.h | 1 +
kernel/time/timekeeping.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -327,6 +327,7 @@ extern ktime_t ktime_get(void);
extern ktime_t ktime_get_real(void);
extern ktime_t ktime_get_boottime(void);
extern ktime_t ktime_get_monotonic_offset(void);
+extern ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot);
DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1126,6 +1126,40 @@ void get_xtime_and_monotonic_and_sleep_o
} while (read_seqretry(&xtime_lock, seq));
}
+#ifdef CONFIG_HIGH_RES_TIMERS
+/**
+ * ktime_get_update_offsets - hrtimer helper
+ * @real: pointer to storage for monotonic -> realtime offset
+ * @_boot: pointer to storage for monotonic -> boottime offset
+ *
+ * Returns current monotonic time and updates the offsets
+ * Called from hrtimer_interupt() or retrigger_next_event()
+ */
+ktime_t ktime_get_update_offsets(ktime_t *real, ktime_t *boot)
+{
+ ktime_t now;
+ unsigned int seq;
+ u64 secs, nsecs;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+
+ secs = xtime.tv_sec;
+ nsecs = xtime.tv_nsec;
+ nsecs += timekeeping_get_ns();
+ /* If arch requires, add in gettimeoffset() */
+ nsecs += arch_gettimeoffset();
+
+ *real = offs_real;
+ *boot = offs_boot;
+ } while (read_seqretry(&xtime_lock, seq));
+
+ now = ktime_add_ns(ktime_set(secs, 0), nsecs);
+ now = ktime_sub(now, *real);
+ return now;
+}
+#endif
+
/**
* ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
*/
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Patch "time: Move common updates to a function" has been added to the 3.0-stable tree
2012-07-17 17:33 ` [PATCH 04/11] 3.0.x: time: Move common updates to a function John Stultz
2012-07-17 17:49 ` Jonathan Nieder
@ 2012-07-17 22:50 ` gregkh
1 sibling, 0 replies; 33+ messages in thread
From: gregkh @ 2012-07-17 22:50 UTC (permalink / raw)
To: johnstul, eric.dumazet, gregkh, john.stultz, linux-kernel,
prarit, richardcochran, tglx
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
time: Move common updates to a function
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
time-move-common-updates-to-a-function.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From johnstul@us.ibm.com Tue Jul 17 15:24:46 2012
From: John Stultz <johnstul@us.ibm.com>
Date: Tue, 17 Jul 2012 13:33:51 -0400
Subject: time: Move common updates to a function
To: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>, Eric Dumazet <eric.dumazet@gmail.com>, Richard Cochran <richardcochran@gmail.com>, Prarit Bhargava <prarit@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>, John Stultz <john.stultz@linaro.org>
Message-ID: <1342546438-17534-5-git-send-email-johnstul@us.ibm.com>
From: Thomas Gleixner <tglx@linutronix.de>
This is a backport of cc06268c6a87db156af2daed6e96a936b955cc82
While not a bugfix itself, it allows following fixes to backport
in a more straightforward manner.
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/time/timekeeping.c | 34 +++++++++++++++++-----------------
1 file changed, 17 insertions(+), 17 deletions(-)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -166,6 +166,19 @@ static struct timespec total_sleep_time;
*/
static struct timespec raw_time;
+/* must hold write on xtime_lock */
+static void timekeeping_update(bool clearntp)
+{
+ if (clearntp) {
+ timekeeper.ntp_error = 0;
+ ntp_clear();
+ }
+ update_vsyscall(&xtime, &wall_to_monotonic,
+ timekeeper.clock, timekeeper.mult);
+}
+
+
+
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
@@ -366,11 +379,7 @@ int do_settimeofday(const struct timespe
xtime = *tv;
- timekeeper.ntp_error = 0;
- ntp_clear();
-
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
+ timekeeping_update(true);
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -403,11 +412,7 @@ int timekeeping_inject_offset(struct tim
xtime = timespec_add(xtime, *ts);
wall_to_monotonic = timespec_sub(wall_to_monotonic, *ts);
- timekeeper.ntp_error = 0;
- ntp_clear();
-
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
+ timekeeping_update(true);
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -630,10 +635,7 @@ void timekeeping_inject_sleeptime(struct
__timekeeping_inject_sleeptime(delta);
- timekeeper.ntp_error = 0;
- ntp_clear();
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
+ timekeeping_update(true);
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -938,9 +940,7 @@ static void update_wall_time(void)
wall_to_monotonic.tv_sec -= leap;
}
- /* check to see if there is a new clocksource to use */
- update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
- timekeeper.mult);
+ timekeeping_update(false);
}
/**
Patches currently in stable-queue which might be from johnstul@us.ibm.com are
queue-3.0/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.0/time-move-common-updates-to-a-function.patch
queue-3.0/timekeeping-fix-clock_monotonic-inconsistency-during-leapsecond.patch
queue-3.0/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.0/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.0/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.0/hrtimer-provide-clock_was_set_delayed.patch
queue-3.0/ntp-fix-leap-second-hrtimer-livelock.patch
queue-3.0/timekeeping-provide-hrtimer-update-function.patch
queue-3.0/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
queue-3.0/ntp-correct-tai-offset-during-leap-second.patch
^ permalink raw reply [flat|nested] 33+ messages in thread
* Re: [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
` (11 preceding siblings ...)
2012-07-17 17:57 ` [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue Willy Tarreau
@ 2012-07-17 22:50 ` Greg KH
12 siblings, 0 replies; 33+ messages in thread
From: Greg KH @ 2012-07-17 22:50 UTC (permalink / raw)
To: John Stultz; +Cc: stable, Prarit Bhargava, Thomas Gleixner, Linux Kernel
On Tue, Jul 17, 2012 at 01:33:47PM -0400, John Stultz wrote:
> Here is backport of the leapsecond fixes to 3.0-stable. These are less
> straight forward, and should get closer review.
Thanks, all applied now.
greg k-h
^ permalink raw reply [flat|nested] 33+ messages in thread
end of thread, other threads:[~2012-07-17 22:52 UTC | newest]
Thread overview: 33+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-07-17 17:33 [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue John Stultz
2012-07-17 17:33 ` [PATCH 01/11] 3.0.x: ntp: Fix leap-second hrtimer livelock John Stultz
2012-07-17 22:49 ` Patch "ntp: Fix leap-second hrtimer livelock" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 02/11] 3.0.x: ntp: Correct TAI offset during leap second John Stultz
2012-07-17 22:49 ` Patch "ntp: Correct TAI offset during leap second" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 03/11] 3.0.x: timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 04/11] 3.0.x: time: Move common updates to a function John Stultz
2012-07-17 17:49 ` Jonathan Nieder
2012-07-17 22:50 ` Patch "time: Move common updates to a function" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 05/11] 3.0.x: hrtimer: Provide clock_was_set_delayed() John Stultz
2012-07-17 22:49 ` Patch "hrtimer: Provide clock_was_set_delayed()" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 06/11] 3.0.x: timekeeping: Fix leapsecond triggered load spike issue John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Fix leapsecond triggered load spike issue" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 07/11] 3.0.x: timekeeping: Maintain ktime_t based offsets for hrtimers John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Maintain ktime_t based offsets for hrtimers" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 08/11] 3.0.x: hrtimers: Move lock held region in hrtimer_interrupt() John Stultz
2012-07-17 22:49 ` Patch "hrtimers: Move lock held region in hrtimer_interrupt()" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 09/11] 3.0.x: timekeeping: Provide hrtimer update function John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Provide hrtimer update function" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 10/11] 3.0.x: hrtimer: Update hrtimer base offsets each hrtimer_interrupt John Stultz
2012-07-17 22:49 ` Patch "hrtimer: Update hrtimer base offsets each hrtimer_interrupt" has been added to the 3.0-stable tree gregkh
2012-07-17 17:33 ` [PATCH 11/11] 3.0.x: timekeeping: Add missing update call in timekeeping_resume() John Stultz
2012-07-17 22:49 ` Patch "timekeeping: Add missing update call in timekeeping_resume()" has been added to the 3.0-stable tree gregkh
2012-07-17 17:57 ` [PATCH 00/11] 3.0-stable: Fix for leapsecond deadlock & hrtimer/futex issue Willy Tarreau
2012-07-17 18:15 ` John Stultz
2012-07-17 18:20 ` John Stultz
2012-07-17 18:26 ` Jonathan Nieder
2012-07-17 19:04 ` John Stultz
2012-07-17 19:14 ` Jonathan Nieder
2012-07-17 19:18 ` John Stultz
2012-07-17 19:05 ` Willy Tarreau
2012-07-17 22:50 ` Greg KH
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