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Commit 76f8507f authored by Kirill Tkhai's avatar Kirill Tkhai Committed by Ingo Molnar
Browse files

locking/rwsem: Add down_read_killable() 



Similar to down_read() and down_write_killable(),
add killable version of down_read(), based on
__down_read_killable() function, added in previous
patches.

Signed-off-by: default avatarKirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arnd@arndb.de
Cc: avagin@virtuozzo.com
Cc: davem@davemloft.net
Cc: fenghua.yu@intel.com
Cc: gorcunov@virtuozzo.com
Cc: heiko.carstens@de.ibm.com
Cc: hpa@zytor.com
Cc: ink@jurassic.park.msu.ru
Cc: mattst88@gmail.com
Cc: rientjes@google.com
Cc: rth@twiddle.net
Cc: schwidefsky@de.ibm.com
Cc: tony.luck@intel.com
Cc: viro@zeniv.linux.org.uk
Link: http://lkml.kernel.org/r/150670119884.23930.2585570605960763239.stgit@localhost.localdomain


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 19c60923

include/asm-generic/rwsem.h

+10 −0
Original line number Diff line number Diff line
@@ -37,6 +37,16 @@ static inline void __down_read(struct rw_semaphore *sem) 
		rwsem_down_read_failed(sem);

}



static inline int __down_read_killable(struct rw_semaphore *sem)

{

	if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) {

		if (IS_ERR(rwsem_down_read_failed_killable(sem)))

			return -EINTR;

	}



	return 0;

}



static inline int __down_read_trylock(struct rw_semaphore *sem)

{

	long tmp;

include/linux/rwsem.h

+1 −0
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ static inline int rwsem_is_contended(struct rw_semaphore *sem) 
 * lock for reading

 */

extern void down_read(struct rw_semaphore *sem);

extern int __must_check down_read_killable(struct rw_semaphore *sem);



/*

 * trylock for reading -- returns 1 if successful, 0 if contention

kernel/locking/rwsem.c

+16 −0
Original line number Diff line number Diff line
@@ -28,6 +28,22 @@ void __sched down_read(struct rw_semaphore *sem) 


EXPORT_SYMBOL(down_read);



int __sched down_read_killable(struct rw_semaphore *sem)

{

	might_sleep();

	rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);



	if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_killable)) {

		rwsem_release(&sem->dep_map, 1, _RET_IP_);

		return -EINTR;

	}



	rwsem_set_reader_owned(sem);

	return 0;

}



EXPORT_SYMBOL(down_read_killable);



/*

 * trylock for reading -- returns 1 if successful, 0 if contention

 */