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Commit 19c60923 authored by Kirill Tkhai's avatar Kirill Tkhai Committed by Ingo Molnar
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locking/arch, x86: Add __down_read_killable() 



Similar to __down_write_killable(), add read killable primitive:
extract current __down_read() code to macros and teach it to get
different functions as slow_path argument:
store ax register to ret, and add sp register and preserve its value.

Add call_rwsem_down_read_failed_killable() assembly entry similar
to call_rwsem_down_read_failed():
push dx register to stack in additional to common registers,
as it's not declarated as modifiable in ____down_read().

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/150670118802.23930.1316107715255410256.stgit@localhost.localdomain


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a61ba2c8

arch/x86/include/asm/rwsem.h

+25 −10
Original line number Diff line number Diff line
@@ -60,18 +60,33 @@ 
/*

 * lock for reading

 */

#define ____down_read(sem, slow_path)					\

({									\

	struct rw_semaphore* ret;					\

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

		     LOCK_PREFIX _ASM_INC "(%[sem])\n\t"		\

		     /* adds 0x00000001 */				\

		     "  jns        1f\n"				\

		     "  call " slow_path "\n"				\

		     "1:\n\t"						\

		     "# ending down_read\n\t"				\

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

			ASM_CALL_CONSTRAINT				\

		     : [sem] "a" (sem)					\

		     : "memory", "cc");					\

	ret;								\

})



static inline void __down_read(struct rw_semaphore *sem)

{

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

		     LOCK_PREFIX _ASM_INC "(%[sem])\n\t"

		     /* adds 0x00000001 */

		     "  jns        1f\n"

		     "  call call_rwsem_down_read_failed\n"

		     "1:\n\t"

		     "# ending down_read\n\t"

		     : "+m" (sem->count)

		     : [sem] "a" (sem)

		     : "memory", "cc");

	____down_read(sem, "call_rwsem_down_read_failed");

}



static inline int __down_read_killable(struct rw_semaphore *sem)

{

	if (IS_ERR(____down_read(sem, "call_rwsem_down_read_failed_killable")))

		return -EINTR;

	return 0;

}



/*

arch/x86/lib/rwsem.S

+12 −0
Original line number Diff line number Diff line
@@ -98,6 +98,18 @@ ENTRY(call_rwsem_down_read_failed) 
	ret

ENDPROC(call_rwsem_down_read_failed)



ENTRY(call_rwsem_down_read_failed_killable)

	FRAME_BEGIN

	save_common_regs

	__ASM_SIZE(push,) %__ASM_REG(dx)

	movq %rax,%rdi

	call rwsem_down_read_failed_killable

	__ASM_SIZE(pop,) %__ASM_REG(dx)

	restore_common_regs

	FRAME_END

	ret

ENDPROC(call_rwsem_down_read_failed_killable)



ENTRY(call_rwsem_down_write_failed)

	FRAME_BEGIN

	save_common_regs