From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3v1n0M1hK8zDqTx for ; Mon, 16 Jan 2017 06:45:38 +1100 (AEDT) Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v0FJi73E060652 for ; Sun, 15 Jan 2017 14:45:35 -0500 Received: from e37.co.us.ibm.com (e37.co.us.ibm.com [32.97.110.158]) by mx0b-001b2d01.pphosted.com with ESMTP id 280enmh2jf-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Sun, 15 Jan 2017 14:45:35 -0500 Received: from localhost by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sun, 15 Jan 2017 12:45:34 -0700 Date: Sun, 15 Jan 2017 11:45:26 -0800 From: "Paul E. McKenney" To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, will.deacon@arm.com, boqun.feng@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, Peter Zijlstra Subject: Re: [PATCH tip/core/rcu 2/3] srcu: Force full grace-period ordering Reply-To: paulmck@linux.vnet.ibm.com References: <20170114091941.GA22961@linux.vnet.ibm.com> <1484385601-23379-2-git-send-email-paulmck@linux.vnet.ibm.com> <20170114093550.GB14970@gmail.com> <20170114195417.GW5238@linux.vnet.ibm.com> <20170114214159.GA7098@linux.vnet.ibm.com> <20170115071123.GB26581@gmail.com> <20170115074034.GE5238@linux.vnet.ibm.com> <20170115075711.GA19506@gmail.com> <20170115092454.GF5238@linux.vnet.ibm.com> <20170115094058.GB28621@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20170115094058.GB28621@gmail.com> Message-Id: <20170115194526.GH5238@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sun, Jan 15, 2017 at 10:40:58AM +0100, Ingo Molnar wrote: > > * Paul E. McKenney wrote: > > > > [sounds of rummaging around in the Git tree] > > > > > > I found this commit of yours from ancient history (more than a year ago!): > > > > > > commit 12d560f4ea87030667438a169912380be00cea4b > > > Author: Paul E. McKenney > > > Date: Tue Jul 14 18:35:23 2015 -0700 > > > > > > rcu,locking: Privatize smp_mb__after_unlock_lock() > > > > > > RCU is the only thing that uses smp_mb__after_unlock_lock(), and is > > > likely the only thing that ever will use it, so this commit makes this > > > macro private to RCU. > > > > > > Signed-off-by: Paul E. McKenney > > > Cc: Will Deacon > > > Cc: Peter Zijlstra > > > Cc: Benjamin Herrenschmidt > > > Cc: "linux-arch@vger.kernel.org" > > > > > > So I concur and I'm fine with your patch - or with the status quo code as well. > > > > I already have the patch queued, so how about I keep it if I get an ack > > from the powerpc guys and drop it otherwise? > > Yeah, sounds good! Your patch made me look up 'RelAcq' so it has documentation > value as well ;-) ;-) ;-) ;-) Looking forward, my guess would be that if some other code needs smp_mb__after_unlock_lock() or if some other architecture needs non-smb_mb() special handling, I should consider making it work the same as smp_mb__after_atomic() and friends. Does that seem like a reasonable thought? Thanx, Paul