From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54146) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dwK5Z-0003QR-2h for qemu-devel@nongnu.org; Sun, 24 Sep 2017 23:29:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dwK5V-0007iG-Vh for qemu-devel@nongnu.org; Sun, 24 Sep 2017 23:29:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49942) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dwK5V-0007hw-NT for qemu-devel@nongnu.org; Sun, 24 Sep 2017 23:29:41 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D89D4C04B944 for ; Mon, 25 Sep 2017 03:29:39 +0000 (UTC) Date: Mon, 25 Sep 2017 11:29:33 +0800 From: Peter Xu Message-ID: <20170925032933.GB19505@pxdev.xzpeter.org> References: <1506070572-7549-1-git-send-email-peterx@redhat.com> <1506070572-7549-3-git-send-email-peterx@redhat.com> <20170922130626.GE32000@lemon> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170922130626.GE32000@lemon> Subject: Re: [Qemu-devel] [PATCH 2/3] iothread: export iothread_stop() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: qemu-devel@nongnu.org, "Dr . David Alan Gilbert" , Stefan Hajnoczi , Paolo Bonzini On Fri, Sep 22, 2017 at 09:06:26PM +0800, Fam Zheng wrote: > On Fri, 09/22 16:56, Peter Xu wrote: > > So that internal iothread users can explicitly stop one iothread without > > destroying it. > > > > Since at it, fix iothread_stop() to allow re-entrance. Before this > > I don't think there is any re-entrace here. Maybe you mean > > s/re-entrance/calling multiple times/ > > ? Yes, you are right. > > > patch we may call iothread_stop() twice on single iothread, while that > > may not be correct since qemu_thread_join() is not allowed to run twice. > > From manual of pthread_join(): > > Is one call from iothread_stop_all() and one from object finalize? Yes. > > > > > Joining with a thread that has previously been joined results in > > undefined behavior. > > > > Signed-off-by: Peter Xu > > --- > > include/sysemu/iothread.h | 1 + > > iothread.c | 24 ++++++++++++++++-------- > > 2 files changed, 17 insertions(+), 8 deletions(-) > > > > diff --git a/include/sysemu/iothread.h b/include/sysemu/iothread.h > > index b07663f..110329b 100644 > > --- a/include/sysemu/iothread.h > > +++ b/include/sysemu/iothread.h > > @@ -52,6 +52,7 @@ GMainContext *iothread_get_g_main_context(IOThread *iothread); > > * "query-iothreads". > > */ > > IOThread *iothread_create(const char *id, Error **errp); > > +void iothread_stop(IOThread *iothread); > > void iothread_destroy(IOThread *iothread); > > > > #endif /* IOTHREAD_H */ > > diff --git a/iothread.c b/iothread.c > > index 74e400c..894756b 100644 > > --- a/iothread.c > > +++ b/iothread.c > > @@ -80,13 +80,10 @@ static void *iothread_run(void *opaque) > > return NULL; > > } > > > > -static int iothread_stop(Object *object, void *opaque) > > +void iothread_stop(IOThread *iothread) > > { > > - IOThread *iothread; > > - > > - iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); > > - if (!iothread || !iothread->ctx) { > > - return 0; > > + if (iothread->stopping) { > > + return; > > } > > iothread->stopping = true; > > aio_notify(iothread->ctx); > > @@ -94,6 +91,17 @@ static int iothread_stop(Object *object, void *opaque) > > g_main_loop_quit(iothread->main_loop); > > } > > qemu_thread_join(&iothread->thread); > > +} > > + > > +static int iothread_stop_iter(Object *object, void *opaque) > > +{ > > + IOThread *iothread; > > + > > + iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); > > + if (!iothread || !iothread->ctx) { > > + return 0; > > + } > > I think the check of iothread->ctx can be moved to iothread_stop() too. Yes, will do. -- Peter Xu