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 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 8B8DFC77B7D for ; Wed, 17 May 2023 16:53:22 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pzKNM-00043k-2r; Wed, 17 May 2023 12:51:44 -0400 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 1pzKNI-0003zz-0o for qemu-devel@nongnu.org; Wed, 17 May 2023 12:51:40 -0400 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 1pzKNG-0001SE-61 for qemu-devel@nongnu.org; Wed, 17 May 2023 12:51:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684342297; 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=CNWzPU7pGQLYS7VpRfgExLTx8ajdrV+obUyytQcMbTE=; b=XhK9zjWiLOunSJUvhkl9SqsZWThwRZu4JJHSXIB7e29QV3PvM6RYjCjhZtmRAhCHM074Ew +maywOcuiiHEqCH+QTk4dx7bcwAuE/iByzEoSoW6BXXuuztFr1HixM+JUzUJjH9445SLsA vp3QT0b3qQlBK3XHzOG5skbWtn+tHIg= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-42-prXHn0HjNK-W0K6EVhQDMQ-1; Wed, 17 May 2023 12:51:34 -0400 X-MC-Unique: prXHn0HjNK-W0K6EVhQDMQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 14F961824602; Wed, 17 May 2023 16:51:34 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.39.194.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5CE3640C6EC4; Wed, 17 May 2023 16:51:33 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, richard.henderson@linaro.org, qemu-devel@nongnu.org Subject: [PULL 11/18] qemu-img: Take graph lock more selectively Date: Wed, 17 May 2023 18:51:09 +0200 Message-Id: <20230517165116.475123-12-kwolf@redhat.com> In-Reply-To: <20230517165116.475123-1-kwolf@redhat.com> References: <20230517165116.475123-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 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=-0.001, 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_H2=-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 If we take a reader lock, we can't call any functions that take a writer lock internally without causing deadlocks once the reader lock is actually enforced in the main thread, too. Take the reader lock only where it is actually needed. Signed-off-by: Kevin Wolf Message-Id: <20230510203601.418015-5-kwolf@redhat.com> Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- qemu-img.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/qemu-img.c b/qemu-img.c index 9f9f0a7629..27f48051b0 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -2938,8 +2938,6 @@ static BlockGraphInfoList *collect_image_info_list(bool image_opts, } bs = blk_bs(blk); - GRAPH_RDLOCK_GUARD_MAINLOOP(); - /* * Note that the returned BlockGraphInfo object will not have * information about this image's backing node, because we have opened @@ -2947,7 +2945,10 @@ static BlockGraphInfoList *collect_image_info_list(bool image_opts, * duplicate the backing chain information that we obtain by walking * the chain manually here. */ + bdrv_graph_rdlock_main_loop(); bdrv_query_block_graph_info(bs, &info, &err); + bdrv_graph_rdunlock_main_loop(); + if (err) { error_report_err(err); blk_unref(blk); -- 2.40.1