linux-kernel - [RFC][PATCH 3/7] locking,x86: Remove x86 rwsem add and rwsem update

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Date:	Mon, 16 May 2016 17:38:02 -0700
From:	Jason Low <jason.low2@....com>
To:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Richard Henderson <rth@...ddle.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Matt Turner <mattst88@...il.com>,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Terry Rudd <terry.rudd@....com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Arnd Bergmann <arnd@...db.de>,
	Christoph Lameter <cl@...ux.com>,
	Davidlohr Bueso <dave@...olabs.net>,
	Waiman Long <Waiman.Long@....com>,
	Tim Chen <tim.c.chen@...ux.intel.com>,
	Peter Hurley <peter@...leysoftware.com>,
	Jason Low <jason.low2@...com>, Jason Low <jason.low2@....com>
Subject: [RFC][PATCH 3/7] locking,x86: Remove x86 rwsem add and rwsem update

The rwsem count has been converted to an atomic variable and the rwsem
code now directly uses atomic_long_add() and atomic_long_add_return(),
so we can remove the x86 implementation of rwsem_atomic_add() and
rwsem_atomic_update().

Signed-off-by: Jason Low <jason.low2@....com>
---
 arch/x86/include/asm/rwsem.h | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index d2f8d10..91cf42c 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -215,23 +215,5 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
 		     : "memory", "cc");
 }
 
-/*
- * implement atomic add functionality
- */
-static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
-{
-	asm volatile(LOCK_PREFIX _ASM_ADD "%1,%0"
-		     : "+m" (sem->count)
-		     : "er" (delta));
-}
-
-/*
- * implement exchange and add functionality
- */
-static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
-{
-	return delta + xadd(&sem->count, delta);
-}
-
 #endif /* __KERNEL__ */
 #endif /* _ASM_X86_RWSEM_H */
-- 
2.1.4