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Commit 916633a4 authored by Michal Hocko's avatar Michal Hocko Committed by Ingo Molnar
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locking/rwsem: Provide down_write_killable() 



Now that all the architectures implement the necessary glue code
we can introduce down_write_killable(). The only difference wrt. regular
down_write() is that the slow path waits in TASK_KILLABLE state and the
interruption by the fatal signal is reported as -EINTR to the caller.

Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Signed-off-by: Jason Low <jason.low2@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/1460041951-22347-12-git-send-email-mhocko@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 664b4e24

arch/x86/include/asm/rwsem.h

+3 −3
Original line number Diff line number Diff line
@@ -102,9 +102,9 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) 
#define ____down_write(sem, slow_path)			\

({							\

	long tmp;					\

	struct rw_semaphore* ret = sem;			\

	struct rw_semaphore* ret;			\

	asm volatile("# beginning down_write\n\t"	\

		     LOCK_PREFIX "  xadd      %1,(%2)\n\t"	\

		     LOCK_PREFIX "  xadd      %1,(%3)\n\t"	\

		     /* adds 0xffff0001, returns the old value */ \

		     "  test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" \

		     /* was the active mask 0 before? */\
@@ -112,7 +112,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) 
		     "  call " slow_path "\n"		\

		     "1:\n"				\

		     "# ending down_write"		\

		     : "+m" (sem->count), "=d" (tmp), "+a" (ret)	\

		     : "+m" (sem->count), "=d" (tmp), "=a" (ret)	\

		     : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) \

		     : "memory", "cc");			\

	ret;						\

include/linux/lockdep.h

+15 −0
Original line number Diff line number Diff line
@@ -444,6 +444,18 @@ do { \ 
	lock_acquired(&(_lock)->dep_map, _RET_IP_);			\

} while (0)



#define LOCK_CONTENDED_RETURN(_lock, try, lock)			\

({								\

	int ____err = 0;					\

	if (!try(_lock)) {					\

		lock_contended(&(_lock)->dep_map, _RET_IP_);	\

		____err = lock(_lock);				\

	}							\

	if (!____err)						\

		lock_acquired(&(_lock)->dep_map, _RET_IP_);	\

	____err;						\

})



#else /* CONFIG_LOCK_STAT */



#define lock_contended(lockdep_map, ip) do {} while (0)
@@ -452,6 +464,9 @@ do { \ 
#define LOCK_CONTENDED(_lock, try, lock) \

	lock(_lock)



#define LOCK_CONTENDED_RETURN(_lock, try, lock) \

	lock(_lock)



#endif /* CONFIG_LOCK_STAT */



#ifdef CONFIG_LOCKDEP

include/linux/rwsem.h

+1 −0
Original line number Diff line number Diff line
@@ -118,6 +118,7 @@ extern int down_read_trylock(struct rw_semaphore *sem); 
 * lock for writing

 */

extern void down_write(struct rw_semaphore *sem);

extern int __must_check down_write_killable(struct rw_semaphore *sem);



/*

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

kernel/locking/rwsem.c

+19 −0
Original line number Diff line number Diff line
@@ -54,6 +54,25 @@ void __sched down_write(struct rw_semaphore *sem) 


EXPORT_SYMBOL(down_write);



/*

 * lock for writing

 */

int __sched down_write_killable(struct rw_semaphore *sem)

{

	might_sleep();

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



	if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock, __down_write_killable)) {

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

		return -EINTR;

	}



	rwsem_set_owner(sem);

	return 0;

}



EXPORT_SYMBOL(down_write_killable);



/*

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

 */