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Commit 664b4e24 authored by Michal Hocko's avatar Michal Hocko Committed by Ingo Molnar
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locking/rwsem, x86: Provide __down_write_killable() 



which uses the same fast path as __down_write() except it falls back to
call_rwsem_down_write_failed_killable() slow path and return -EINTR if
killed. To prevent from code duplication extract the skeleton of
__down_write() into a helper macro which just takes the semaphore
and the slow path function to be called.

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/1460041951-22347-11-git-send-email-mhocko@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 4edab14e

arch/x86/include/asm/rwsem.h

+28 −13
Original line number Diff line number Diff line
@@ -99,21 +99,36 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) 
/*

 * lock for writing

 */

#define ____down_write(sem, slow_path)			\

({							\

	long tmp;					\

	struct rw_semaphore* ret = sem;			\

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

		     LOCK_PREFIX "  xadd      %1,(%2)\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? */\

		     "  jz        1f\n"			\

		     "  call " slow_path "\n"		\

		     "1:\n"				\

		     "# ending down_write"		\

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

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

		     : "memory", "cc");			\

	ret;						\

})



static inline void __down_write(struct rw_semaphore *sem)

{

	long tmp;

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

		     LOCK_PREFIX "  xadd      %1,(%2)\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? */

		     "  jz        1f\n"

		     "  call call_rwsem_down_write_failed\n"

		     "1:\n"

		     "# ending down_write"

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

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

		     : "memory", "cc");

	____down_write(sem, "call_rwsem_down_write_failed");

}



static inline int __down_write_killable(struct rw_semaphore *sem)

{

	if (IS_ERR(____down_write(sem, "call_rwsem_down_write_failed_killable")))

		return -EINTR;



	return 0;

}



/*

arch/x86/lib/rwsem.S

+8 −0
Original line number Diff line number Diff line
@@ -106,6 +106,14 @@ ENTRY(call_rwsem_down_write_failed) 
	ret

ENDPROC(call_rwsem_down_write_failed)



ENTRY(call_rwsem_down_write_failed_killable)

	save_common_regs

	movq %rax,%rdi

	call rwsem_down_write_failed_killable

	restore_common_regs

	ret

ENDPROC(call_rwsem_down_write_failed_killable)



ENTRY(call_rwsem_wake)

	FRAME_BEGIN

	/* do nothing if still outstanding active readers */