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 93D7FC49ED9 for ; Thu, 12 Sep 2019 09:55:31 +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 6B9B8206A5 for ; Thu, 12 Sep 2019 09:55:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6B9B8206A5 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]:60088 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8Lp4-0000y7-59 for qemu-devel@archiver.kernel.org; Thu, 12 Sep 2019 05:55:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49287) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8Lnf-0007tK-Qz for qemu-devel@nongnu.org; Thu, 12 Sep 2019 05:54:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i8Lne-0004dS-P3 for qemu-devel@nongnu.org; Thu, 12 Sep 2019 05:54:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37356) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i8Lne-0004cl-GS for qemu-devel@nongnu.org; Thu, 12 Sep 2019 05:54:02 -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 3691310CC1E0; Thu, 12 Sep 2019 09:54:01 +0000 (UTC) Received: from work-vm (unknown [10.36.118.12]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 54BBD10AFDEA; Thu, 12 Sep 2019 09:54:00 +0000 (UTC) Date: Thu, 12 Sep 2019 10:53:57 +0100 From: "Dr. David Alan Gilbert" To: Ivan Ren Message-ID: <20190912095357.GA7230@work-vm> References: <1567044996-2362-1-git-send-email-ivanren@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1567044996-2362-1-git-send-email-ivanren@tencent.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]); Thu, 12 Sep 2019 09:54:01 +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] migration: multifd_send_thread always post p->sem_sync when error happen 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: qemu-devel@nongnu.org, quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Queued * Ivan Ren (renyime@gmail.com) wrote: > From: Ivan Ren > > When encounter error, multifd_send_thread should always notify who pay > attention to it before exit. Otherwise it may block migration_thread > at multifd_send_sync_main forever. > > Error as follow: > ------------------------------------------------------------------------------- > (gdb) bt > #0 0x00007f4d669dfa0b in do_futex_wait.constprop.1 () from /lib64/libpthread.so.0 > #1 0x00007f4d669dfa9f in __new_sem_wait_slow.constprop.0 () from /lib64/libpthread.so.0 > #2 0x00007f4d669dfb3b in sem_wait@@GLIBC_2.2.5 () from /lib64/libpthread.so.0 > #3 0x0000562ccf0a5614 in qemu_sem_wait (sem=sem@entry=0x562cd1b698e8) at util/qemu-thread-posix.c:319 > #4 0x0000562ccecb4752 in multifd_send_sync_main (rs=) at /qemu/migration/ram.c:1099 > #5 0x0000562ccecb95f4 in ram_save_iterate (f=0x562cd0ecc000, opaque=) at /qemu/migration/ram.c:3550 > #6 0x0000562ccef43c23 in qemu_savevm_state_iterate (f=0x562cd0ecc000, postcopy=false) at migration/savevm.c:1189 > #7 0x0000562ccef3dcf3 in migration_iteration_run (s=0x562cd09fabf0) at migration/migration.c:3131 > #8 migration_thread (opaque=opaque@entry=0x562cd09fabf0) at migration/migration.c:3258 > #9 0x0000562ccf0a4c26 in qemu_thread_start (args=) at util/qemu-thread-posix.c:502 > #10 0x00007f4d669d9e25 in start_thread () from /lib64/libpthread.so.0 > #11 0x00007f4d6670635d in clone () from /lib64/libc.so.6 > (gdb) f 4 > #4 0x0000562ccecb4752 in multifd_send_sync_main (rs=) at /qemu/migration/ram.c:1099 > 1099 qemu_sem_wait(&p->sem_sync); > (gdb) list > 1094 } > 1095 for (i = 0; i < migrate_multifd_channels(); i++) { > 1096 MultiFDSendParams *p = &multifd_send_state->params[i]; > 1097 > 1098 trace_multifd_send_sync_main_wait(p->id); > 1099 qemu_sem_wait(&p->sem_sync); > 1100 } > 1101 trace_multifd_send_sync_main(multifd_send_state->packet_num); > 1102 } > 1103 > (gdb) p i > $1 = 0 > (gdb) p multifd_send_state->params[0].pending_job > $2 = 2 //It means the job before MULTIFD_FLAG_SYNC has already fail > (gdb) p multifd_send_state->params[0].quit > $3 = true > > Signed-off-by: Ivan Ren > --- > migration/ram.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index b01a37e7ca..0047286b7e 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -1112,6 +1112,7 @@ static void *multifd_send_thread(void *opaque) > rcu_register_thread(); > > if (multifd_send_initial_packet(p, &local_err) < 0) { > + ret = -1; > goto out; > } > /* initial packet */ > @@ -1179,9 +1180,7 @@ out: > * who pay attention to me. > */ > if (ret != 0) { > - if (flags & MULTIFD_FLAG_SYNC) { > - qemu_sem_post(&p->sem_sync); > - } > + qemu_sem_post(&p->sem_sync); > qemu_sem_post(&multifd_send_state->channels_ready); > } > > -- > 2.17.2 (Apple Git-113) > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK