From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH -v3 7/8] locking: Move smp_cond_load_acquire() and friends into asm-generic/barrier.h Date: Wed, 1 Jun 2016 13:13:33 +0100 Message-ID: <20160601121333.GC355@arm.com> References: <20160531094134.606249808@infradead.org> <20160531094844.282806055@infradead.org> <574DED82.9080200@hpe.com> <20160601093158.GN3190@twins.programming.kicks-ass.net> <20160601120009.GB355@arm.com> <20160601120654.GR3190@twins.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Waiman Long , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, manfred@colorfullife.com, dave@stgolabs.net, paulmck@linux.vnet.ibm.com, boqun.feng@gmail.com, tj@kernel.org, pablo@netfilter.org, kaber@trash.net, davem@davemloft.net, oleg@redhat.com, netfilter-devel@vger.kernel.org, sasha.levin@oracle.com, hofrat@osadl.org To: Peter Zijlstra Return-path: Content-Disposition: inline In-Reply-To: <20160601120654.GR3190@twins.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org On Wed, Jun 01, 2016 at 02:06:54PM +0200, Peter Zijlstra wrote: > On Wed, Jun 01, 2016 at 01:00:10PM +0100, Will Deacon wrote: > > On Wed, Jun 01, 2016 at 11:31:58AM +0200, Peter Zijlstra wrote: > > > Will, since ARM64 seems to want to use this, does the below make sense > > > to you? > > > > Not especially -- I was going to override smp_cond_load_acquire anyway > > because I want to build it using cmpwait_acquire and get rid of the > > smp_acquire__after_ctrl_dep trick, which is likely slower on arm64. > > > > So I'd be happier nuking cmpwait from the generic interfaces and using > > smp_cond_load_acquire everywhere, if that's possible. > > Works for me; but that would loose using cmpwait() for > !smp_cond_load_acquire() spins, you fine with that? > > The two conversions in the patch were both !acquire spins. Maybe we could go the whole hog and add smp_cond_load_relaxed? Will