linux-kernel - [PATCH 09/11] s390, rwsem: provide __down_write

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Date:	Thu,  7 Apr 2016 17:12:29 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"David S. Miller" <davem@...emloft.net>,
	Tony Luck <tony.luck@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Chris Zankel <chris@...kel.net>,
	Max Filippov <jcmvbkbc@...il.com>, x86@...nel.org,
	linux-alpha@...r.kernel.org, linux-ia64@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
	sparclinux@...r.kernel.org, linux-xtensa@...ux-xtensa.org,
	linux-arch@...r.kernel.org, Michal Hocko <mhocko@...e.com>
Subject: [PATCH 09/11] s390, rwsem: provide __down_write_killable

From: Michal Hocko <mhocko@...e.com>

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@...e.com>
---
 arch/s390/include/asm/rwsem.h | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/rwsem.h b/arch/s390/include/asm/rwsem.h
index 8e52e72f3efc..8e7b2b7e10f3 100644
--- a/arch/s390/include/asm/rwsem.h
+++ b/arch/s390/include/asm/rwsem.h
@@ -90,7 +90,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
 /*
  * lock for writing
  */
-static inline void __down_write(struct rw_semaphore *sem)
+static inline long ___down_write(struct rw_semaphore *sem)
 {
 	signed long old, new, tmp;
 
@@ -104,10 +104,25 @@ static inline void __down_write(struct rw_semaphore *sem)
 		: "=&d" (old), "=&d" (new), "=Q" (sem->count)
 		: "Q" (sem->count), "m" (tmp)
 		: "cc", "memory");
-	if (old != 0)
+
+	return old;
+}
+
+static inline void __down_write(struct rw_semaphore *sem)
+{
+	if (___down_write(sem))
 		rwsem_down_write_failed(sem);
 }
 
+static inline int __down_write_killable(struct rw_semaphore *sem)
+{
+	if (___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
  */
-- 
2.8.0.rc3