From patchwork Thu Apr 20 20:29:39 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?C=C3=A9dric_Le_Goater?= X-Patchwork-Id: 13219171 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 134CFC77B73 for ; Thu, 20 Apr 2023 20:30:55 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ppauu-0003U1-7b; Thu, 20 Apr 2023 16:30:08 -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 1ppaus-0003Ts-Gt for qemu-devel@nongnu.org; Thu, 20 Apr 2023 16:30:06 -0400 Received: from mail.ozlabs.org ([2404:9400:2221:ea00::3] helo=gandalf.ozlabs.org) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ppaul-0005aQ-OP for qemu-devel@nongnu.org; Thu, 20 Apr 2023 16:30:06 -0400 Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by gandalf.ozlabs.org (Postfix) with ESMTP id 4Q2TmC6C9Zz4xD8; Fri, 21 Apr 2023 06:29:47 +1000 (AEST) Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4Q2Tm80dzsz4x5Q; Fri, 21 Apr 2023 06:29:43 +1000 (AEST) From: =?utf-8?q?C=C3=A9dric_Le_Goater?= To: qemu-devel@nongnu.org Cc: Peter Maydell , Thomas Huth , Daniel Henrique Barboza , =?utf-8?q?Marc-Andr=C3=A9_?= =?utf-8?q?Lureau?= , =?utf-8?q?C=C3=A9dric_Le_?= =?utf-8?q?Goater?= , Stefan Hajnoczi , Paolo Bonzini , =?utf-8?q?Daniel_P_=2E_Berrang=C3=A9?= Subject: [PATCH] async: Suppress GCC13 false positive in aio_bh_poll() Date: Thu, 20 Apr 2023 22:29:39 +0200 Message-Id: <20230420202939.1982044-1-clg@kaod.org> X-Mailer: git-send-email 2.40.0 MIME-Version: 1.0 Received-SPF: pass client-ip=2404:9400:2221:ea00::3; envelope-from=SRS0=NXNv=AL=kaod.org=clg@ozlabs.org; helo=gandalf.ozlabs.org X-Spam_score_int: -39 X-Spam_score: -4.0 X-Spam_bar: ---- X-Spam_report: (-4.0 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham 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 From: Cédric Le Goater GCC13 reports an error : ../util/async.c: In function ‘aio_bh_poll’: include/qemu/queue.h:303:22: error: storing the address of local variable ‘slice’ in ‘*ctx.bh_slice_list.sqh_last’ [-Werror=dangling-pointer=] 303 | (head)->sqh_last = &(elm)->field.sqe_next; \ | ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~ ../util/async.c:169:5: note: in expansion of macro ‘QSIMPLEQ_INSERT_TAIL’ 169 | QSIMPLEQ_INSERT_TAIL(&ctx->bh_slice_list, &slice, next); | ^~~~~~~~~~~~~~~~~~~~ ../util/async.c:161:17: note: ‘slice’ declared here 161 | BHListSlice slice; | ^~~~~ ../util/async.c:161:17: note: ‘ctx’ declared here But the local variable 'slice' is removed from the global context list in following loop of the same routine. Add a pragma to silent GCC. Cc: Stefan Hajnoczi Cc: Paolo Bonzini Cc: Daniel P. Berrangé Signed-off-by: Cédric Le Goater Reviewed-by: Daniel Henrique Barboza Tested-by: Daniel Henrique Barboza Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Stefan Hajnoczi Reviewed-by: Thomas Huth Signed-off-by: Juan Quintela --- util/async.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/util/async.c b/util/async.c index 21016a1ac7..856e1a8a33 100644 --- a/util/async.c +++ b/util/async.c @@ -164,7 +164,21 @@ int aio_bh_poll(AioContext *ctx) /* Synchronizes with QSLIST_INSERT_HEAD_ATOMIC in aio_bh_enqueue(). */ QSLIST_MOVE_ATOMIC(&slice.bh_list, &ctx->bh_list); + + /* + * GCC13 [-Werror=dangling-pointer=] complains that the local variable + * 'slice' is being stored in the global 'ctx->bh_slice_list' but the + * list is emptied before this function returns. + */ +#if !defined(__clang__) +#pragma GCC diagnostic push +#pragma GCC diagnostic ignored "-Wpragmas" +#pragma GCC diagnostic ignored "-Wdangling-pointer=" +#endif QSIMPLEQ_INSERT_TAIL(&ctx->bh_slice_list, &slice, next); +#if !defined(__clang__) +#pragma GCC diagnostic pop +#endif while ((s = QSIMPLEQ_FIRST(&ctx->bh_slice_list))) { QEMUBH *bh;