From: Frederic Weisbecker <frederic@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
"David S . Miller" <davem@davemloft.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Pavan Kondeti <pkondeti@codeaurora.org>,
Ingo Molnar <mingo@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>
Subject: [PATCH 31/37] softirq: Support per vector masking
Date: Thu, 28 Feb 2019 18:12:36 +0100 [thread overview]
Message-ID: <20190228171242.32144-32-frederic@kernel.org> (raw)
In-Reply-To: <20190228171242.32144-1-frederic@kernel.org>
Provide the low level APIs to support per-vector masking. In order
to allow these to properly nest with itself and with full softirq
masking APIs, we provide two mechanisms:
1) Self nesting: use a caller stack saved/restored state model similar to
that of local_irq_save() and local_irq_restore():
bh = local_bh_disable_mask(BIT(NET_RX_SOFTIRQ));
[...]
bh2 = local_bh_disable_mask(BIT(TIMER_SOFTIRQ));
[...]
local_bh_enable_mask(bh2);
local_bh_enable_mask(bh);
2) Nest against full masking: save the per-vector disabled state prior
to the first full disable operation and restore it on the last full
enable operation:
bh = local_bh_disable_mask(BIT(NET_RX_SOFTIRQ));
[...]
local_bh_disable() <---- save state with NET_RX_SOFTIRQ disabled
[...]
local_bh_enable() <---- restore state with NET_RX_SOFTIRQ disabled
local_bh_enable_mask(bh);
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Pavan Kondeti <pkondeti@codeaurora.org>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
---
include/linux/bottom_half.h | 7 +++
kernel/softirq.c | 85 +++++++++++++++++++++++++++++++------
2 files changed, 80 insertions(+), 12 deletions(-)
diff --git a/include/linux/bottom_half.h b/include/linux/bottom_half.h
index ef9e4c752f56..a6996e3f4526 100644
--- a/include/linux/bottom_half.h
+++ b/include/linux/bottom_half.h
@@ -35,6 +35,10 @@ static inline void local_bh_disable(void)
__local_bh_disable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
}
+extern unsigned int local_bh_disable_mask(unsigned long ip,
+ unsigned int cnt, unsigned int mask);
+
+
extern void local_bh_enable_no_softirq(void);
extern void __local_bh_enable_ip(unsigned long ip, unsigned int cnt);
@@ -48,4 +52,7 @@ static inline void local_bh_enable(void)
__local_bh_enable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
}
+extern void local_bh_enable_mask(unsigned long ip, unsigned int cnt,
+ unsigned int mask);
+
#endif /* _LINUX_BH_H */
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 2cddaaff3bfa..bb841e5d9951 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -61,6 +61,7 @@ DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
struct softirq_nesting {
unsigned int disabled_all;
+ unsigned int enabled_vector;
};
static DEFINE_PER_CPU(struct softirq_nesting, softirq_nesting);
@@ -110,8 +111,10 @@ static bool ksoftirqd_running(unsigned long pending)
* softirq and whether we just have bh disabled.
*/
-void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
+static unsigned int local_bh_disable_common(unsigned long ip, unsigned int cnt,
+ bool per_vec, unsigned int vec_mask)
{
+ unsigned int enabled;
#ifdef CONFIG_TRACE_IRQFLAGS
unsigned long flags;
@@ -127,10 +130,31 @@ void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
*/
__preempt_count_add(cnt);
- if (__this_cpu_inc_return(softirq_nesting.disabled_all) == 1) {
- softirq_enabled_clear_mask(SOFTIRQ_ALL_MASK);
- trace_softirqs_off(ip);
- }
+ enabled = local_softirq_enabled();
+
+ /*
+ * Handle nesting of full/per-vector masking. Per vector masking
+ * takes effect only if full masking hasn't taken place yet.
+ */
+ if (!__this_cpu_read(softirq_nesting.disabled_all)) {
+ if (enabled & vec_mask) {
+ softirq_enabled_clear_mask(vec_mask);
+ if (!local_softirq_enabled())
+ trace_softirqs_off(ip);
+ }
+
+ /*
+ * Save the state prior to full masking. We'll restore it
+ * on next non-nesting full unmasking in case some vectors
+ * have been individually disabled before (case of full masking
+ * nesting inside per-vector masked code).
+ */
+ if (!per_vec)
+ __this_cpu_write(softirq_nesting.enabled_vector, enabled);
+ }
+
+ if (!per_vec)
+ __this_cpu_inc(softirq_nesting.disabled_all);
#ifdef CONFIG_TRACE_IRQFLAGS
raw_local_irq_restore(flags);
@@ -142,15 +166,38 @@ void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
#endif
trace_preempt_off(CALLER_ADDR0, get_lock_parent_ip());
}
+
+ return enabled;
+}
+
+void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
+{
+ local_bh_disable_common(ip, cnt, false, SOFTIRQ_ALL_MASK);
}
EXPORT_SYMBOL(__local_bh_disable_ip);
-static void local_bh_enable_common(unsigned long ip, unsigned int cnt)
+unsigned int local_bh_disable_mask(unsigned long ip, unsigned int cnt,
+ unsigned int vec_mask)
{
- if (__this_cpu_dec_return(softirq_nesting.disabled_all))
- return;
+ return local_bh_disable_common(ip, cnt, true, vec_mask);
+}
+EXPORT_SYMBOL(local_bh_disable_mask);
- softirq_enabled_set(SOFTIRQ_ALL_MASK);
+static void local_bh_enable_common(unsigned long ip, unsigned int cnt,
+ bool per_vec, unsigned int mask)
+{
+ /*
+ * Restore the previous softirq mask state. If this was the last
+ * full unmasking, restore what was saved.
+ */
+ if (!per_vec) {
+ if (__this_cpu_dec_return(softirq_nesting.disabled_all))
+ return;
+ else
+ mask = __this_cpu_read(softirq_nesting.enabled_vector);
+ }
+
+ softirq_enabled_set(mask);
trace_softirqs_on(ip);
}
@@ -161,7 +208,7 @@ static void __local_bh_enable_no_softirq(unsigned int cnt)
if (preempt_count() == cnt)
trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
- local_bh_enable_common(_RET_IP_, cnt);
+ local_bh_enable_common(_RET_IP_, cnt, false, SOFTIRQ_ALL_MASK);
__preempt_count_sub(cnt);
}
@@ -177,14 +224,15 @@ void local_bh_enable_no_softirq(void)
}
EXPORT_SYMBOL(local_bh_enable_no_softirq);
-void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
+static void local_bh_enable_ip_mask(unsigned long ip, unsigned int cnt,
+ bool per_vec, unsigned int mask)
{
WARN_ON_ONCE(in_irq());
lockdep_assert_irqs_enabled();
#ifdef CONFIG_TRACE_IRQFLAGS
local_irq_disable();
#endif
- local_bh_enable_common(ip, cnt);
+ local_bh_enable_common(ip, cnt, per_vec, mask);
/*
* Keep preemption disabled until we are done with
@@ -206,8 +254,21 @@ void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
#endif
preempt_check_resched();
}
+
+void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
+{
+ local_bh_enable_ip_mask(ip, cnt, false, SOFTIRQ_ALL_MASK);
+}
EXPORT_SYMBOL(__local_bh_enable_ip);
+void local_bh_enable_mask(unsigned long ip, unsigned int cnt,
+ unsigned int mask)
+{
+ local_bh_enable_ip_mask(ip, cnt, true, mask);
+}
+EXPORT_SYMBOL(local_bh_enable_mask);
+
+
/*
* We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
* but break the loop if need_resched() is set or after 2 ms.
--
2.21.0
next prev parent reply other threads:[~2019-02-28 17:14 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 17:12 [PATCH 00/37] softirq: Per vector masking v3 Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 01/37] locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 02/37] locking/lockdep: Use expanded masks on find_usage_*() functions Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 03/37] locking/lockdep: Introduce struct lock_usage Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 04/37] locking/lockdep: Convert usage_mask to u64 Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 05/37] locking/lockdep: Introduce lock usage mask iterator Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 06/37] locking/lockdep: Test all incompatible scenario at once in check_irq_usage() Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 07/37] locking/lockdep: Prepare valid_state() to handle plain masks Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 08/37] locking/lockdep: Prepare check_usage_*() " Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 09/37] locking/lockdep: Prepare state_verbose() to handle all softirqs Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 10/37] locking/lockdep: Make mark_lock() fastpath to work with multiple usage at once Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 11/37] locking/lockdep: Save stack trace for each softirq vector involved Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 12/37] locking/lockdep: Report all usages on mark_lock() verbosity mode Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 13/37] softirq: Macrofy softirq vectors Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 14/37] locking/lockdep: Define per vector softirq lock usage states Frederic Weisbecker
2019-04-09 12:03 ` Peter Zijlstra
2019-02-28 17:12 ` [PATCH 15/37] softirq: Pass softirq vector number to lockdep on vector execution Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 16/37] x86: Revert "x86/irq: Demote irq_cpustat_t::__softirq_pending to u16" Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 17/37] arch/softirq: Rename softirq_pending fields to softirq_data Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 18/37] softirq: Normalize softirq_pending naming scheme Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 19/37] softirq: Convert softirq_pending_*() to set/clear mask scheme Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 20/37] softirq: Introduce disabled softirq vectors bits Frederic Weisbecker
2019-03-01 11:29 ` Sebastian Andrzej Siewior
2019-02-28 17:12 ` [PATCH 21/37] softirq: Rename _local_bh_enable() to local_bh_enable_no_softirq() Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 22/37] softirq: Move vectors bits to bottom_half.h Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 23/37] x86: Init softirq enabled field Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 24/37] parisc: " Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 25/37] powerpc: " Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 26/37] softirq: Init softirq enabled field for default irq_stat definition Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 27/37] softirq: Check enabled vectors before processing Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 28/37] softirq: Remove stale comment Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 29/37] softirq: Uninline !CONFIG_TRACE_IRQFLAGS __local_bh_disable_ip() Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 30/37] softirq: Prepare for mixing all/per-vector masking Frederic Weisbecker
2019-02-28 17:12 ` Frederic Weisbecker [this message]
2019-02-28 17:12 ` [PATCH 32/37] locking/lockdep: Remove redundant softirqs on check Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 33/37] locking/lockdep: Update check_flags() according to new layout Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 34/37] locking/lockdep: Branch the new vec-finegrained softirq masking to lockdep Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 35/37] softirq: Allow to soft interrupt vector-specific masked contexts Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 36/37] locking: Introduce spin_[un]lock_bh_mask() Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 37/37] net: Make softirq vector masking finegrained on release_sock() Frederic Weisbecker
2019-02-28 17:33 ` [PATCH 00/37] softirq: Per vector masking v3 Linus Torvalds
2019-03-01 3:45 ` Frederic Weisbecker
2019-03-01 16:51 ` Linus Torvalds
2019-03-08 15:30 ` Frederic Weisbecker
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