From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40859) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKPn7-0001oB-Cg for qemu-devel@nongnu.org; Tue, 05 Jul 2016 08:49:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bKPn2-0004dd-Dn for qemu-devel@nongnu.org; Tue, 05 Jul 2016 08:49:28 -0400 Received: from mail-wm0-x22d.google.com ([2a00:1450:400c:c09::22d]:38214) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKPn2-0004dX-7G for qemu-devel@nongnu.org; Tue, 05 Jul 2016 08:49:24 -0400 Received: by mail-wm0-x22d.google.com with SMTP id r201so151194605wme.1 for ; Tue, 05 Jul 2016 05:49:24 -0700 (PDT) Sender: Paolo Bonzini References: <1467389770-9738-1-git-send-email-alex.bennee@linaro.org> <1467389770-9738-2-git-send-email-alex.bennee@linaro.org> <20160702001736.GA2295@flamenco> <87y45kiki8.fsf@linaro.org> <20160704223132.GB29624@flamenco> From: Paolo Bonzini Message-ID: Date: Tue, 5 Jul 2016 14:49:19 +0200 MIME-Version: 1.0 In-Reply-To: <20160704223132.GB29624@flamenco> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1/2] tcg: Ensure safe tb_jmp_cache lookup out of 'tb_lock' List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Emilio G. Cota" , =?UTF-8?Q?Alex_Benn=c3=a9e?= Cc: mttcg@listserver.greensocs.com, peter.maydell@linaro.org, claudio.fontana@huawei.com, Sergey Fedorov , Peter Crosthwaite , jan.kiszka@siemens.com, mark.burton@greensocs.com, a.rigo@virtualopensystems.com, qemu-devel@nongnu.org, serge.fdrv@gmail.com, bobby.prani@gmail.com, rth@twiddle.net, fred.konrad@greensocs.com On 05/07/2016 00:31, Emilio G. Cota wrote: > My mistake. An atomic_read here isn't needed: as the commit message > points out, we only need atomic_read when tb_lock isn't held. In this > case tb_lock is held, so we only use atomic accesses for writing > to the array. It's harmless though. In C11 and C++11 it would even be required, so I think it's better to add it even though our compilers don't yet enforce it. Paolo