From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46603) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aqhEy-0003HR-NU for qemu-devel@nongnu.org; Thu, 14 Apr 2016 09:23:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aqhEv-00047i-BV for qemu-devel@nongnu.org; Thu, 14 Apr 2016 09:23:24 -0400 Received: from mail-pa0-x244.google.com ([2607:f8b0:400e:c03::244]:34274) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aqhEv-000478-2t for qemu-devel@nongnu.org; Thu, 14 Apr 2016 09:23:21 -0400 Received: by mail-pa0-x244.google.com with SMTP id hb4so6862381pac.1 for ; Thu, 14 Apr 2016 06:23:20 -0700 (PDT) Sender: Paolo Bonzini References: <1460629215-11567-1-git-send-email-den@openvz.org> From: Paolo Bonzini Message-ID: <570F99C5.3050801@redhat.com> Date: Thu, 14 Apr 2016 15:23:17 +0200 MIME-Version: 1.0 In-Reply-To: <1460629215-11567-1-git-send-email-den@openvz.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for 2.6 1/1] nbd: fix assert() on qemu-nbd stop List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Denis V. Lunev" , qemu-devel@nongnu.org Cc: Pavel Butsykin , Max Reitz On 14/04/2016 12:20, Denis V. Lunev wrote: > From: Pavel Butsykin > > From time to time qemu-nbd is crashing on the following assert: > assert(state == TERMINATING); > nbd_export_closed > nbd_export_put > main > and the state at the moment of the crash is evaluated to TERMINATE. > > During shutdown process of the client the nbd_client_thread thread sends > SIGTERM signal and the main thread calls the nbd_client_closed callback. > If the SIGTERM callback will be executed after change the state to > TERMINATING, then the state will once again be TERMINATE. > > To solve the issue, we must change the state to TERMINATE only if the state > is RUNNING. In the other case we are shutting down already. > > Signed-off-by: Pavel Butsykin > Signed-off-by: Denis V. Lunev > CC: Paolo Bonzini > --- > qemu-nbd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/qemu-nbd.c b/qemu-nbd.c > index ca4a724..956013f 100644 > --- a/qemu-nbd.c > +++ b/qemu-nbd.c > @@ -213,7 +213,7 @@ static int find_partition(BlockBackend *blk, int partition, > > static void termsig_handler(int signum) > { > - state = TERMINATE; > + atomic_cmpxchg(&state, RUNNING, TERMINATE); Just a simple "if" is enough (the rest of the file is not using any of atomic{mb_,}{read,set}. I'm not able to send further pull requests for 2.6, can the block maintainers help? Paolo > qemu_notify_event(); > } > >