Commit c3921ab7 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Add new 'cond_resched_bkl()' helper function 



It acts exactly like a regular 'cond_resched()', but will not get
optimized away when CONFIG_PREEMPT is set.

Normal kernel code is already preemptable in the presense of
CONFIG_PREEMPT, so cond_resched() is optimized away (see commit
02b67cc3 "sched: do not do
cond_resched() when CONFIG_PREEMPT").

But when wanting to conditionally reschedule while holding a lock, you
need to use "cond_sched_lock(lock)", and the new function is the BKL
equivalent of that.

Also make fs/locks.c use it.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 96623697

fs/locks.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -773,7 +773,7 @@ static int flock_lock_file(struct file *filp, struct file_lock *request) 
	 * give it the opportunity to lock the file.

	 * give it the opportunity to lock the file.

	 */

	 */

	if (found)

	if (found)

		cond_resched();

		cond_resched_bkl();





find_conflict:

find_conflict:

	for_each_lock(inode, before) {

	for_each_lock(inode, before) {

include/linux/sched.h

+5 −1
Original line number Original line Diff line number Diff line
@@ -2037,13 +2037,13 @@ static inline int need_resched(void) 
 * cond_resched_lock() will drop the spinlock before scheduling,

 * cond_resched_lock() will drop the spinlock before scheduling,

 * cond_resched_softirq() will enable bhs before scheduling.

 * cond_resched_softirq() will enable bhs before scheduling.

 */

 */

extern int _cond_resched(void);

#ifdef CONFIG_PREEMPT

#ifdef CONFIG_PREEMPT

static inline int cond_resched(void)

static inline int cond_resched(void)

{

{

	return 0;

	return 0;

}

}

#else

#else

extern int _cond_resched(void);

static inline int cond_resched(void)

static inline int cond_resched(void)

{

{

	return _cond_resched();

	return _cond_resched();
@@ -2051,6 +2051,10 @@ static inline int cond_resched(void) 
#endif

#endif

extern int cond_resched_lock(spinlock_t * lock);

extern int cond_resched_lock(spinlock_t * lock);

extern int cond_resched_softirq(void);

extern int cond_resched_softirq(void);

static inline int cond_resched_bkl(void)

{

	return _cond_resched();

}





/*

/*

 * Does a critical section need to be broken due to another

 * Does a critical section need to be broken due to another

kernel/sched.c

+0 −2
Original line number Original line Diff line number Diff line
@@ -5525,7 +5525,6 @@ static void __cond_resched(void) 
	} while (need_resched());

	} while (need_resched());

}

}





#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PREEMPT_VOLUNTARY)

int __sched _cond_resched(void)

int __sched _cond_resched(void)

{

{

	if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&

	if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&
@@ -5536,7 +5535,6 @@ int __sched _cond_resched(void) 
	return 0;

	return 0;

}

}

EXPORT_SYMBOL(_cond_resched);

EXPORT_SYMBOL(_cond_resched);

#endif





/*

/*

 * cond_resched_lock() - if a reschedule is pending, drop the given lock,

 * cond_resched_lock() - if a reschedule is pending, drop the given lock,

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