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sched: Add cond_resched_rwlock

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Safely rescheduling while holding a spin lock is essential for keeping
long running kernel operations running smoothly. Add the facility to
cond_resched rwlocks.

CC: Ingo Molnar <mingo@redhat.com>
CC: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210202185734.1680553-9-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ben Gardon 2021-02-02 10:57:14 -08:00 committed by Paolo Bonzini
parent a09a689a53
commit f3d4b4b1dc
2 changed files with 52 additions and 0 deletions
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12
include/linux/sched.h
View file

@ -1883,12 +1883,24 @@ static inline int _cond_resched(void) { return 0; }
})
extern int __cond_resched_lock(spinlock_t *lock);
extern int __cond_resched_rwlock_read(rwlock_t *lock);
extern int __cond_resched_rwlock_write(rwlock_t *lock);
#define cond_resched_lock(lock) ({ \
___might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET);\
__cond_resched_lock(lock); \
})
#define cond_resched_rwlock_read(lock) ({ \
__might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \
__cond_resched_rwlock_read(lock); \
})
#define cond_resched_rwlock_write(lock) ({ \
__might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \
__cond_resched_rwlock_write(lock); \
})
static inline void cond_resched_rcu(void)
{
#if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)

40
kernel/sched/core.c
View file

@ -6695,6 +6695,46 @@ int __cond_resched_lock(spinlock_t *lock)
}
EXPORT_SYMBOL(__cond_resched_lock);
int __cond_resched_rwlock_read(rwlock_t *lock)
{
int resched = should_resched(PREEMPT_LOCK_OFFSET);
int ret = 0;
lockdep_assert_held_read(lock);
if (rwlock_needbreak(lock) || resched) {
read_unlock(lock);
if (resched)
preempt_schedule_common();
else
cpu_relax();
ret = 1;
read_lock(lock);
}
return ret;
}
EXPORT_SYMBOL(__cond_resched_rwlock_read);
int __cond_resched_rwlock_write(rwlock_t *lock)
{
int resched = should_resched(PREEMPT_LOCK_OFFSET);
int ret = 0;
lockdep_assert_held_write(lock);
if (rwlock_needbreak(lock) || resched) {
write_unlock(lock);
if (resched)
preempt_schedule_common();
else
cpu_relax();
ret = 1;
write_lock(lock);
}
return ret;
}
EXPORT_SYMBOL(__cond_resched_rwlock_write);
/**
* yield - yield the current processor to other threads.
*