linux-kernel - [RFC][PATCH 0/7] locking/rwsem: Convert rwsem count to atomic_long

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Date:	Mon, 16 May 2016 17:37:59 -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>
Subject: [RFC][PATCH 0/7] locking/rwsem: Convert rwsem count to atomic_long_t

The first patch contains an optimization for acquiring the rwsem write lock
in the slowpath.

This rest of the series converts the rwsem count variable to an atomic_long_t
since it is used it as an atomic variable. This allows us to also remove
the rwsem_atomic_{add,update} abstraction and reduce 100+ lines of code.

 arch/alpha/include/asm/rwsem.h | 42 --------------------------------
 arch/ia64/include/asm/rwsem.h  |  7 ------
 arch/s390/include/asm/rwsem.h  | 37 -----------------------------
 arch/x86/include/asm/rwsem.h   | 18 --------------
 include/asm-generic/rwsem.h    | 16 -------------
 include/linux/rwsem.h          |  6 ++---
 kernel/locking/rwsem-xadd.c    | 54 ++++++++++++++++++++++++++----------------
 7 files changed, 36 insertions(+), 144 deletions(-)

-- 
2.1.4