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

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Message-Id: <1459508695-14915-10-git-send-email-mhocko@kernel.org>
Date:	Fri,  1 Apr 2016 13:04:53 +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] xtensa, rwsem: provide __down_write_killable

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

which uses the same fast path as __down_write except it falls back to
rwsem_down_write_failed_killable slow path and return -EINTR if killed.

Signed-off-by: Michal Hocko <mhocko@...e.com>
---
 arch/xtensa/include/asm/rwsem.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/xtensa/include/asm/rwsem.h b/arch/xtensa/include/asm/rwsem.h
index 593483f6e1ff..6283823b8040 100644
--- a/arch/xtensa/include/asm/rwsem.h
+++ b/arch/xtensa/include/asm/rwsem.h
@@ -59,6 +59,19 @@ static inline void __down_write(struct rw_semaphore *sem)
 		rwsem_down_write_failed(sem);
 }
 
+static inline int __down_write_killable(struct rw_semaphore *sem)
+{
+	int tmp;
+
+	tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
+				(atomic_t *)(&sem->count));
+	if (tmp != RWSEM_ACTIVE_WRITE_BIAS)
+		if (IS_ERR(rwsem_down_write_failed_killable(sem)))
+			return -EINTR;
+
+	return 0;
+}
+
 static inline int __down_write_trylock(struct rw_semaphore *sem)
 {
 	int tmp;
-- 
2.8.0.rc3