From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A40A0C5ACAE for ; Wed, 11 Sep 2019 18:53:34 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 801D020578 for ; Wed, 11 Sep 2019 18:53:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 801D020578 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:55576 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i87kD-0007PK-IG for qemu-devel@archiver.kernel.org; Wed, 11 Sep 2019 14:53:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51097) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i87jJ-0006xj-Gy for qemu-devel@nongnu.org; Wed, 11 Sep 2019 14:52:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i87jI-0006Vo-HD for qemu-devel@nongnu.org; Wed, 11 Sep 2019 14:52:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55836) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i87jI-0006Um-BK for qemu-devel@nongnu.org; Wed, 11 Sep 2019 14:52:36 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6CF2110CC1E3 for ; Wed, 11 Sep 2019 18:52:35 +0000 (UTC) Received: from work-vm (ovpn-117-243.ams2.redhat.com [10.36.117.243]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 41DAD1001944; Wed, 11 Sep 2019 18:52:34 +0000 (UTC) Date: Wed, 11 Sep 2019 19:52:31 +0100 From: "Dr. David Alan Gilbert" To: Eric Blake Message-ID: <20190911185231.GO2894@work-vm> References: <20190911164202.31136-1-dgilbert@redhat.com> <20190911164202.31136-2-dgilbert@redhat.com> <1a03f787-5cf8-6b8e-7489-3f90c3311032@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1a03f787-5cf8-6b8e-7489-3f90c3311032@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.65]); Wed, 11 Sep 2019 18:52:35 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 1/3] rcu: Add automatically released rcu_read_lock variant X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pbonzini@redhat.com, berrange@redhat.com, qemu-devel@nongnu.org, quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Eric Blake (eblake@redhat.com) wrote: > On 9/11/19 11:42 AM, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > RCU_READ_LOCK_AUTO takes the rcu_read_lock and then uses glib's > > g_auto infrastrcture (and thus whatever the compilers hooks are) to > > release it on all exits of the block. > > > > Note this macro has a variable declaration in, and hence is not in > > a while loop. > > > > Signed-off-by: Dr. David Alan Gilbert > > --- > > include/qemu/rcu.h | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h > > index 22876d1428..6a25b27d28 100644 > > --- a/include/qemu/rcu.h > > +++ b/include/qemu/rcu.h > > @@ -154,6 +154,18 @@ extern void call_rcu1(struct rcu_head *head, RCUCBFunc *func); > > }), \ > > (RCUCBFunc *)g_free); > > > > +typedef char rcu_read_auto_t; > > Declaring new types ending in _t collides with the namespace reserved by > POSIX. While I don't think it will bite us, it's still worth > considering if a different name is better. Thanks, I've renamed it to 'RCUReadAuto' which is closer to what we normally use for typedef's (albeit normally of structs) Dave > > +static inline void rcu_read_auto_unlock(rcu_read_auto_t *r) > > +{ > > + rcu_read_unlock(); > > +} > > + > > +G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(rcu_read_auto_t, rcu_read_auto_unlock) > > + > > +#define RCU_READ_LOCK_AUTO g_auto(rcu_read_auto_t) \ > > + _rcu_read_auto = 'x'; \ > > I'm a bit lost at where _rcu_read_auto is declared. (I could understand > if an earlier macro had created that typedef via concatenating _ with > rcu_read_auto_t, but making the preprocessor drop _t is not possible. Is > this a typo, and if so, why did the compiler not complain?) > > > + rcu_read_lock(); > > + > > #ifdef __cplusplus > > } > > #endif > > > > -- > Eric Blake, Principal Software Engineer > Red Hat, Inc. +1-919-301-3226 > Virtualization: qemu.org | libvirt.org > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK