[tip:locking/rwsem] locking/rwsem, alpha: Provide __down_write_killable()

[tip-bot for Michal Hocko]

Commit-ID:  7deb5eebc1e61b15c5c7f1ef19f216b20d7f7d00
Gitweb:     http://git.kernel.org/tip/7deb5eebc1e61b15c5c7f1ef19f216b20d7f7d00
Author:     Michal Hocko <mhocko@xxxxxxxx>
AuthorDate: Thu, 7 Apr 2016 17:12:27 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 13 Apr 2016 10:42:21 +0200

locking/rwsem, alpha: Provide __down_write_killable()

Introduce ___down_write() for the fast path and reuse it for __down_write()
resp. __down_write_killable() each using the respective generic slow path
(rwsem_down_write_failed() resp. rwsem_down_write_failed_killable()).

Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Chris Zankel <chris@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Signed-off-by: Jason Low <jason.low2@xxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: linux-alpha@xxxxxxxxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: linux-ia64@xxxxxxxxxxxxxxx
Cc: linux-s390@xxxxxxxxxxxxxxx
Cc: linux-sh@xxxxxxxxxxxxxxx
Cc: linux-xtensa@xxxxxxxxxxxxxxxx
Cc: sparclinux@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1460041951-22347-8-git-send-email-mhocko@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/alpha/include/asm/rwsem.h | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/arch/alpha/include/asm/rwsem.h b/arch/alpha/include/asm/rwsem.h
index a83bbea..0131a70 100644
--- a/arch/alpha/include/asm/rwsem.h
+++ b/arch/alpha/include/asm/rwsem.h
@@ -63,7 +63,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
 	return res >= 0 ? 1 : 0;
 }
 
-static inline void __down_write(struct rw_semaphore *sem)
+static inline long ___down_write(struct rw_semaphore *sem)
 {
 	long oldcount;
 #ifndef	CONFIG_SMP
@@ -83,10 +83,24 @@ static inline void __down_write(struct rw_semaphore *sem)
 	:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
 	:"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");
 #endif
-	if (unlikely(oldcount))
+	return oldcount;
+}
+
+static inline void __down_write(struct rw_semaphore *sem)
+{
+	if (unlikely(___down_write(sem)))
 		rwsem_down_write_failed(sem);
 }
 
+static inline int __down_write_killable(struct rw_semaphore *sem)
+{
+	if (unlikely(___down_write(sem)))
+		if (IS_ERR(rwsem_down_write_failed_killable(sem)))
+			return -EINTR;
+
+	return 0;
+}
+
 /*
  * trylock for writing -- returns 1 if successful, 0 if contention
  */