From patchwork Tue Oct 27 15:15:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 301809 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=-9.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED 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 826A6C71156 for ; Tue, 27 Oct 2020 15:27:19 +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 E75AF222EA for ; Tue, 27 Oct 2020 15:27:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="XqqsmH/B" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E75AF222EA 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]:50072 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kXQsX-0003j7-PP for qemu-devel@archiver.kernel.org; Tue, 27 Oct 2020 11:27:17 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57906) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kXQhL-0006DQ-9J for qemu-devel@nongnu.org; Tue, 27 Oct 2020 11:15:43 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:32414) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kXQhA-0007gP-0U for qemu-devel@nongnu.org; Tue, 27 Oct 2020 11:15:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603811729; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=aojtNcYM5JZGocHlr42uqtul6nag2xreruX+X6NpCKo=; b=XqqsmH/Brw5oJY7K45fpVonCdT6+tUkebWLZDCbAQI3Rwy6l9zoqlMkSFDE99DgQGcLSoe bmtjG8iIJw10jEMsLZzBh+MqGaY5Y8WOq0fFG7h6EoiJOxM4t9cL3H/6s0F7nT10ORghCR +o+yA5lCatlrXY39SJLiKsaMEjK0zZA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-43-fLL_FNFrOtuRZIyp8XumJQ-1; Tue, 27 Oct 2020 11:15:26 -0400 X-MC-Unique: fLL_FNFrOtuRZIyp8XumJQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 25B4F8030DB; Tue, 27 Oct 2020 15:15:25 +0000 (UTC) Received: from merkur.redhat.com (ovpn-114-16.ams2.redhat.com [10.36.114.16]) by smtp.corp.redhat.com (Postfix) with ESMTP id 265AD55762; Tue, 27 Oct 2020 15:15:23 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PULL 5/5] block: End quiescent sections when a BDS is deleted Date: Tue, 27 Oct 2020 16:15:15 +0100 Message-Id: <20201027151515.213565-6-kwolf@redhat.com> In-Reply-To: <20201027151515.213565-1-kwolf@redhat.com> References: <20201027151515.213565-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/27 01:06:06 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Greg Kurz If a BDS gets deleted during blk_drain_all(), it might miss a call to bdrv_do_drained_end(). This means missing a call to aio_enable_external() and the AIO context remains disabled for ever. This can cause a device to become irresponsive and to disrupt the guest execution, ie. hang, loop forever or worse. This scenario is quite easy to encounter with virtio-scsi on POWER when punching multiple blockdev-create QMP commands while the guest is booting and it is still running the SLOF firmware. This happens because SLOF disables/re-enables PCI devices multiple times via IO/MEM/MASTER bits of PCI_COMMAND register after the initial probe/feature negotiation, as it tends to work with a single device at a time at various stages like probing and running block/network bootloaders without doing a full reset in-between. This naturally generates many dataplane stops and starts, and thus many drain sections that can race with blockdev_create_run(). In the end, SLOF bails out. It is somehow reproducible on x86 but it requires to generate articial dataplane start/stop activity with stop/cont QMP commands. In this case, seabios ends up looping for ever, waiting for the virtio-scsi device to send a response to a command it never received. Add a helper that pairs all previously called bdrv_do_drained_begin() with a bdrv_do_drained_end() and call it from bdrv_close(). While at it, update the "/bdrv-drain/graph-change/drain_all" test in test-bdrv-drain so that it can catch the issue. BugId: https://bugzilla.redhat.com/show_bug.cgi?id=1874441 Signed-off-by: Greg Kurz Message-Id: <160346526998.272601.9045392804399803158.stgit@bahia.lan> Signed-off-by: Kevin Wolf --- include/block/block.h | 6 ++++++ block.c | 9 +++++++++ block/io.c | 13 +++++++++++++ tests/test-bdrv-drain.c | 1 + 4 files changed, 29 insertions(+) diff --git a/include/block/block.h b/include/block/block.h index c9d7c58765..4bfe3b546b 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -781,6 +781,12 @@ void bdrv_drained_end(BlockDriverState *bs); */ void bdrv_drained_end_no_poll(BlockDriverState *bs, int *drained_end_counter); +/** + * End all quiescent sections started by bdrv_drain_all_begin(). This is + * only needed when deleting a BDS before bdrv_drain_all_end() is called. + */ +void bdrv_drain_all_end_quiesce(BlockDriverState *bs); + /** * End a quiescent section started by bdrv_subtree_drained_begin(). */ diff --git a/block.c b/block.c index 430edf79bb..ee5b28a979 100644 --- a/block.c +++ b/block.c @@ -4458,6 +4458,15 @@ static void bdrv_close(BlockDriverState *bs) } QLIST_INIT(&bs->aio_notifiers); bdrv_drained_end(bs); + + /* + * If we're still inside some bdrv_drain_all_begin()/end() sections, end + * them now since this BDS won't exist anymore when bdrv_drain_all_end() + * gets called. + */ + if (bs->quiesce_counter) { + bdrv_drain_all_end_quiesce(bs); + } } void bdrv_close_all(void) diff --git a/block/io.c b/block/io.c index c33cecd58d..9918f2499c 100644 --- a/block/io.c +++ b/block/io.c @@ -633,6 +633,19 @@ void bdrv_drain_all_begin(void) } } +void bdrv_drain_all_end_quiesce(BlockDriverState *bs) +{ + int drained_end_counter = 0; + + g_assert(bs->quiesce_counter > 0); + g_assert(!bs->refcnt); + + while (bs->quiesce_counter) { + bdrv_do_drained_end(bs, false, NULL, true, &drained_end_counter); + } + BDRV_POLL_WHILE(bs, qatomic_read(&drained_end_counter) > 0); +} + void bdrv_drain_all_end(void) { BlockDriverState *bs = NULL; diff --git a/tests/test-bdrv-drain.c b/tests/test-bdrv-drain.c index 1595bbc92e..8a29e33e00 100644 --- a/tests/test-bdrv-drain.c +++ b/tests/test-bdrv-drain.c @@ -594,6 +594,7 @@ static void test_graph_change_drain_all(void) g_assert_cmpint(bs_b->quiesce_counter, ==, 0); g_assert_cmpint(b_s->drain_count, ==, 0); + g_assert_cmpint(qemu_get_aio_context()->external_disable_cnt, ==, 0); bdrv_unref(bs_b); blk_unref(blk_b);