From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59799) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WNMLu-0007oZ-Pa for qemu-devel@nongnu.org; Tue, 11 Mar 2014 09:04:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WNMLm-0001hA-BK for qemu-devel@nongnu.org; Tue, 11 Mar 2014 09:04:14 -0400 Received: from mail-ea0-x22b.google.com ([2a00:1450:4013:c01::22b]:56316) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WNMLm-0001gD-4T for qemu-devel@nongnu.org; Tue, 11 Mar 2014 09:04:06 -0400 Received: by mail-ea0-f171.google.com with SMTP id n15so4323236ead.30 for ; Tue, 11 Mar 2014 06:04:05 -0700 (PDT) Message-ID: <1394543062.3981.41.camel@localhost.localdomain> From: Marcel Apfelbaum Date: Tue, 11 Mar 2014 15:04:22 +0200 In-Reply-To: <1394542311.3981.37.camel@localhost.localdomain> References: <1394532550-21857-1-git-send-email-marcel.a@redhat.com> <1394532550-21857-2-git-send-email-marcel.a@redhat.com> <20140311124022.GA7761@stefanha-thinkpad.redhat.com> <1394542311.3981.37.camel@localhost.localdomain> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V2 1/2] tests/libqtest: Fix possible deadlock in qtest initialization Reply-To: marcel.a@redhat.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: kwolf@redhat.com, stefanha@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com, aliguori@amazon.com, afaerber@suse.de On Tue, 2014-03-11 at 14:51 +0200, Marcel Apfelbaum wrote: > On Tue, 2014-03-11 at 13:40 +0100, Stefan Hajnoczi wrote: > > On Tue, Mar 11, 2014 at 12:09:09PM +0200, Marcel Apfelbaum wrote: > > > @@ -78,12 +79,16 @@ static int socket_accept(int sock) > > > struct sockaddr_un addr; > > > socklen_t addrlen; > > > int ret; > > > + struct timeval timeout = { .tv_sec = SOCKET_TIMEOUT, > > > + .tv_usec = 0 }; > > > + > > > + setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (void *)&timeout, > > > + sizeof(timeout)); > > > > > > addrlen = sizeof(addr); > > > do { > > > ret = accept(sock, (struct sockaddr *)&addr, &addrlen); > > > } while (ret == -1 && errno == EINTR); > > > - g_assert_no_errno(ret); > > > close(sock); > > > > Did you mean to leave SO_RCVTIMEO set after this function completes? > Yes, I don't think it hurts. A 5 sec timeout should be like infinite, > Qemu running on the same machine. If you think ... otherwise, I can remove the timeout, but I think it is OK. > > > > > > @@ -91,7 +96,7 @@ static int socket_accept(int sock) > > > > > > static void kill_qemu(QTestState *s) > > > { > > > - if (s->qemu_pid != -1) { > > > + if (s && s->qemu_pid != -1) { > > > kill(s->qemu_pid, SIGTERM); > > > waitpid(s->qemu_pid, NULL, 0); > > > } > > > > This is a bug in libqtest.c, please don't silence the crash. > I didn't see it like hiding a crash, I thought that if there > is any problem during init it is because the Qemu failed to start, > meaning that you don't have a process to kill (Qemu exited already). > Al of the above happens -> you don't have a global state. > > Anyway, if you have a better way to deal with it, I have nothing against it :) > > Thanks, > Marcel > > > > > kill_qemu() gets called from the SIGABRT signal handler but I forgot > > that global_qtest isn't initialized yet while qtest_init() executes. > > > > In other words, the cleanup is broken if we fail inside qtest_init(). > > Can you drop this hunk and I'll send a patch to fix the underlying > > issue? I dropped it, please take care of it as it gets a segmentation fault if we abort in qtest_init. Thanks, Marcel > > > > > @@ -153,6 +158,8 @@ QTestState *qtest_init(const char *extra_args) > > > g_free(socket_path); > > > g_free(qmp_socket_path); > > > > > > + g_assert(s->fd >= 0 && s->qmp_fd >= 0); > > > + > > > > We probably shouldn't socket_accept() s->qmp_fd if s->fd already failed. > > Otherwise we'll wait another 5 seconds for the timeout to explire: > Yes, I already had this chunk, I have no idea why I dropped it, I'll > return it, thanks. > > Thanks, > Marcel > > > > s->fd = socket_accept(sock); > > if (s->fd >= 0) { > > s->qmp_fd = socket_accept(qmpsock); > > } > > > >