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>

diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index 4a8292a..d759c5f 100644 (file)
--- 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 (file)
--- 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 */