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Subject[tip:locking/rwsem] locking/rwsem, x86: Provide __down_write_killable()
Commit-ID:  664b4e24c6145830885e854195376351b0eb3eee
Gitweb: http://git.kernel.org/tip/664b4e24c6145830885e854195376351b0eb3eee
Author: Michal Hocko <mhocko@suse.com>
AuthorDate: Thu, 7 Apr 2016 17:12:30 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 13 Apr 2016 10:42:22 +0200

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: Michal 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: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/rwsem.h | 41 ++++++++++++++++++++++++++++-------------
arch/x86/lib/rwsem.S | 8 ++++++++
2 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index 4a8292a..d759c5f 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -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;
}

/*
diff --git a/arch/x86/lib/rwsem.S b/arch/x86/lib/rwsem.S
index be110ef..4534a7e 100644
--- a/arch/x86/lib/rwsem.S
+++ b/arch/x86/lib/rwsem.S
@@ -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 */
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