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author | Konstantin Khlebnikov <khlebnikov@yandex-team.ru> | 2015-07-15 12:52:04 +0300 |
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committer | Luis Henriques <luis.henriques@canonical.com> | 2015-11-16 11:27:24 +0000 |
commit | b72279e4ca0b488f9724f830f0fe81c1a0c26cd8 (patch) | |
tree | 1122241c60bbf74a398d1cb3188897cb2c7842e4 | |
parent | 1f585b92809e14e13c4e31d2cd2117bbd9dd8074 (diff) | |
download | linux-stable-b72279e4ca0b488f9724f830f0fe81c1a0c26cd8.tar.gz linux-stable-b72279e4ca0b488f9724f830f0fe81c1a0c26cd8.tar.bz2 linux-stable-b72279e4ca0b488f9724f830f0fe81c1a0c26cd8.zip |
sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()
commit fe32d3cd5e8eb0f82e459763374aa80797023403 upstream.
These functions check should_resched() before unlocking spinlock/bh-enable:
preempt_count always non-zero => should_resched() always returns false.
cond_resched_lock() worked iff spin_needbreak is set.
This patch adds argument "preempt_offset" to should_resched().
preempt_count offset constants for that:
PREEMPT_DISABLE_OFFSET - offset after preempt_disable()
PREEMPT_LOCK_OFFSET - offset after spin_lock()
SOFTIRQ_DISABLE_OFFSET - offset after local_bh_distable()
SOFTIRQ_LOCK_OFFSET - offset after spin_lock_bh()
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: bdb438065890 ("sched: Extract the basic add/sub preempt_count modifiers")
Link: http://lkml.kernel.org/r/20150715095204.12246.98268.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[ luis: backported to 3.16:
- some of the changes done in preempt_mask.h instead of preempt.h
- adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
-rw-r--r-- | arch/x86/include/asm/preempt.h | 4 | ||||
-rw-r--r-- | include/asm-generic/preempt.h | 5 | ||||
-rw-r--r-- | include/linux/preempt.h | 5 | ||||
-rw-r--r-- | include/linux/preempt_mask.h | 14 | ||||
-rw-r--r-- | include/linux/sched.h | 6 | ||||
-rw-r--r-- | kernel/sched/core.c | 6 |
6 files changed, 22 insertions, 18 deletions
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h index 7024c12f7bfe..cebe6d05891e 100644 --- a/arch/x86/include/asm/preempt.h +++ b/arch/x86/include/asm/preempt.h @@ -93,9 +93,9 @@ static __always_inline bool __preempt_count_dec_and_test(void) /* * Returns true when we need to resched and can (barring IRQ state). */ -static __always_inline bool should_resched(void) +static __always_inline bool should_resched(int preempt_offset) { - return unlikely(!raw_cpu_read_4(__preempt_count)); + return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset); } #ifdef CONFIG_PREEMPT diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h index 1cd3f5d767a8..54352f4dde1a 100644 --- a/include/asm-generic/preempt.h +++ b/include/asm-generic/preempt.h @@ -74,9 +74,10 @@ static __always_inline bool __preempt_count_dec_and_test(void) /* * Returns true when we need to resched and can (barring IRQ state). */ -static __always_inline bool should_resched(void) +static __always_inline bool should_resched(int preempt_offset) { - return unlikely(!preempt_count() && tif_need_resched()); + return unlikely(preempt_count() == preempt_offset && + tif_need_resched()); } #ifdef CONFIG_PREEMPT diff --git a/include/linux/preempt.h b/include/linux/preempt.h index de83b4eb1642..8cd6725c5758 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -20,7 +20,8 @@ #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) extern void preempt_count_add(int val); extern void preempt_count_sub(int val); -#define preempt_count_dec_and_test() ({ preempt_count_sub(1); should_resched(); }) +#define preempt_count_dec_and_test() \ + ({ preempt_count_sub(1); should_resched(0); }) #else #define preempt_count_add(val) __preempt_count_add(val) #define preempt_count_sub(val) __preempt_count_sub(val) @@ -59,7 +60,7 @@ do { \ #define preempt_check_resched() \ do { \ - if (should_resched()) \ + if (should_resched(0)) \ __preempt_schedule(); \ } while (0) diff --git a/include/linux/preempt_mask.h b/include/linux/preempt_mask.h index 1f654ee836b7..5cb25f17331a 100644 --- a/include/linux/preempt_mask.h +++ b/include/linux/preempt_mask.h @@ -71,13 +71,21 @@ */ #define in_nmi() (preempt_count() & NMI_MASK) +/* + * The preempt_count offset after preempt_disable(); + */ #if defined(CONFIG_PREEMPT_COUNT) -# define PREEMPT_DISABLE_OFFSET 1 +# define PREEMPT_DISABLE_OFFSET PREEMPT_OFFSET #else -# define PREEMPT_DISABLE_OFFSET 0 +# define PREEMPT_DISABLE_OFFSET 0 #endif /* + * The preempt_count offset after spin_lock() + */ +#define PREEMPT_LOCK_OFFSET PREEMPT_DISABLE_OFFSET + +/* * The preempt_count offset needed for things like: * * spin_lock_bh() @@ -90,7 +98,7 @@ * * Work as expected. */ -#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_DISABLE_OFFSET) +#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_LOCK_OFFSET) /* * Are we running in atomic context? WARNING: this macro cannot diff --git a/include/linux/sched.h b/include/linux/sched.h index 4bab946551e9..a632aaad1e59 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2736,12 +2736,6 @@ extern int _cond_resched(void); extern int __cond_resched_lock(spinlock_t *lock); -#ifdef CONFIG_PREEMPT_COUNT -#define PREEMPT_LOCK_OFFSET PREEMPT_OFFSET -#else -#define PREEMPT_LOCK_OFFSET 0 -#endif - #define cond_resched_lock(lock) ({ \ __might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \ __cond_resched_lock(lock); \ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c1d7818dade9..c80729679806 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4172,7 +4172,7 @@ static void __cond_resched(void) int __sched _cond_resched(void) { - if (should_resched()) { + if (should_resched(0)) { __cond_resched(); return 1; } @@ -4190,7 +4190,7 @@ EXPORT_SYMBOL(_cond_resched); */ int __cond_resched_lock(spinlock_t *lock) { - int resched = should_resched(); + int resched = should_resched(PREEMPT_LOCK_OFFSET); int ret = 0; lockdep_assert_held(lock); @@ -4212,7 +4212,7 @@ int __sched __cond_resched_softirq(void) { BUG_ON(!in_softirq()); - if (should_resched()) { + if (should_resched(SOFTIRQ_DISABLE_OFFSET)) { local_bh_enable(); __cond_resched(); local_bh_disable(); |