Commit f3d4b4b1 authored by Ben Gardon's avatar Ben Gardon Committed by Paolo Bonzini
Browse files

sched: Add cond_resched_rwlock 



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: default avatarPeter Zijlstra <peterz@infradead.org>
Acked-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Acked-by: default avatarWaiman Long <longman@redhat.com>
Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarBen Gardon <bgardon@google.com>
Message-Id: <20210202185734.1680553-9-bgardon@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent a09a689a

include/linux/sched.h

+12 −0
Original line number Diff line number Diff line
@@ -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)

kernel/sched/core.c

+40 −0
Original line number Diff line number Diff line
@@ -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.

 *