From patchwork Tue Nov 21 11:52:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13462895 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id C33ECC61D92 for ; Tue, 21 Nov 2023 11:54:02 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r5PJg-0003R9-4F; Tue, 21 Nov 2023 06:53:20 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r5PJc-0003OY-7X for qemu-devel@nongnu.org; Tue, 21 Nov 2023 06:53:16 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r5PJa-0004Hr-PY for qemu-devel@nongnu.org; Tue, 21 Nov 2023 06:53:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700567594; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=g5U/U6h9vjsb1p1rSaKlfb5FTQwoOb61k678GR2Ee94=; b=Hm4YQxfm1Hdcf94aI8bBZ+CkCOEGCooKoGdpan3xntRIayKZoHWzdvDV/eu6BH3D22mKTj d1JF3FdK7G7TD5ismjZit1CMuPGfexX3LhEmvhqRHem7nCwKIC29qWTNYbzggnyQ+pIBsq WBROBn/jkkZXP45OjL+Wh7fCu679q9s= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-552-LRawtiKJPbKCzTiDmrQ06A-1; Tue, 21 Nov 2023 06:53:11 -0500 X-MC-Unique: LRawtiKJPbKCzTiDmrQ06A-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C38752825E8F; Tue, 21 Nov 2023 11:53:10 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.39.194.112]) by smtp.corp.redhat.com (Postfix) with ESMTP id 32EAF492BFC; Tue, 21 Nov 2023 11:53:10 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 4/9] stream: Fix AioContext locking during bdrv_graph_wrlock() Date: Tue, 21 Nov 2023 12:52:57 +0100 Message-ID: <20231121115302.52214-5-kwolf@redhat.com> In-Reply-To: <20231121115302.52214-1-kwolf@redhat.com> References: <20231121115302.52214-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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=-0.035, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org In stream_prepare(), we need to temporarily drop the AioContext lock that job_prepare_locked() took for us while calling the graph write lock functions which can poll. All block nodes related to this block job are in the same AioContext, so we can pass any of them to bdrv_graph_wrlock()/ bdrv_graph_wrunlock(). Unfortunately, the one that we picked is base, which can be NULL - and in this case the AioContext lock is not released and deadlocks can occur. Fix this by passing s->target_bs, which is never NULL. Signed-off-by: Kevin Wolf Message-ID: <20231115172012.112727-4-kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/stream.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/block/stream.c b/block/stream.c index e3aa696289..01fe7c0f16 100644 --- a/block/stream.c +++ b/block/stream.c @@ -99,9 +99,9 @@ static int stream_prepare(Job *job) } } - bdrv_graph_wrlock(base); + bdrv_graph_wrlock(s->target_bs); bdrv_set_backing_hd_drained(unfiltered_bs, base, &local_err); - bdrv_graph_wrunlock(base); + bdrv_graph_wrunlock(s->target_bs); /* * This call will do I/O, so the graph can change again from here on.