From patchwork Wed Aug 16 14:25:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabiano Rosas X-Patchwork-Id: 1821864 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=HDrbjv1i; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=bgUKneSO; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=patchwork.ozlabs.org) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4RQr5l5qY4z1yNm for ; Thu, 17 Aug 2023 00:25:47 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qWHSc-0003ty-VM; Wed, 16 Aug 2023 10:25:22 -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 1qWHSb-0003rR-JV for qemu-devel@nongnu.org; Wed, 16 Aug 2023 10:25:21 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qWHSZ-0003jS-DF for qemu-devel@nongnu.org; Wed, 16 Aug 2023 10:25:21 -0400 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 4CD052190B; Wed, 16 Aug 2023 14:25:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1692195918; h=from:from:reply-to: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=jAsBqbZmyUB1R931rGfF3+iNeAKRaD7BagsRZjWBM0I=; b=HDrbjv1idM79n+u3HVqOEjE8Q/SSE+iyjUEuPS3BgUewojaF5U7MUR9XJi2jkoDOtUbJ4X WG7TYuZvoD+uqxL5hrmvmUnrKR9fJboKOQs48GZ9nsBPWyZnVvc0jkpEGHJJoHUxO9J1bg jPQlxa+ho8eHQ/OhkdW5Cq1t8XaDp18= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1692195918; h=from:from:reply-to: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=jAsBqbZmyUB1R931rGfF3+iNeAKRaD7BagsRZjWBM0I=; b=bgUKneSOFHz2OWc7CwozNOIs9zhLHS1ivFbvAeZtqFzbwUUgj7mxMju7FI+KhgSfZVsuZG Xk6/S1iCE7yfAaDg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id BBF41133F2; Wed, 16 Aug 2023 14:25:16 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id oHwNIUzc3GShdwAAMHmgww (envelope-from ); Wed, 16 Aug 2023 14:25:16 +0000 From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: Juan Quintela , Peter Xu , Wei Wang , Leonardo Bras Subject: [PATCH v4 2/8] migration: Fix possible races when shutting down the return path Date: Wed, 16 Aug 2023 11:25:04 -0300 Message-Id: <20230816142510.5637-3-farosas@suse.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230816142510.5637-1-farosas@suse.de> References: <20230816142510.5637-1-farosas@suse.de> MIME-Version: 1.0 Received-SPF: pass client-ip=195.135.220.28; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org We cannot call qemu_file_shutdown() on the return path file without taking the file lock. The return path thread could be running it's cleanup code and have just cleared the from_dst_file pointer. Checking ms->to_dst_file for errors could also race with migrate_fd_cleanup() which clears the to_dst_file pointer. Protect both accesses by taking the file lock. This was caught by inspection, it should be rare, but the next patches will start calling this code from other places, so let's do the correct thing. Signed-off-by: Fabiano Rosas Reviewed-by: Peter Xu --- migration/migration.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index f88c86079c..85c171f32c 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -2052,17 +2052,18 @@ static int open_return_path_on_source(MigrationState *ms, static int await_return_path_close_on_source(MigrationState *ms) { /* - * If this is a normal exit then the destination will send a SHUT and the - * rp_thread will exit, however if there's an error we need to cause - * it to exit. + * If this is a normal exit then the destination will send a SHUT + * and the rp_thread will exit, however if there's an error we + * need to cause it to exit. shutdown(2), if we have it, will + * cause it to unblock if it's stuck waiting for the destination. */ - if (qemu_file_get_error(ms->to_dst_file) && ms->rp_state.from_dst_file) { - /* - * shutdown(2), if we have it, will cause it to unblock if it's stuck - * waiting for the destination. - */ - qemu_file_shutdown(ms->rp_state.from_dst_file); + WITH_QEMU_LOCK_GUARD(&ms->qemu_file_lock) { + if (ms->to_dst_file && ms->rp_state.from_dst_file && + qemu_file_get_error(ms->to_dst_file)) { + qemu_file_shutdown(ms->rp_state.from_dst_file); + } } + trace_await_return_path_close_on_source_joining(); qemu_thread_join(&ms->rp_state.rp_thread); ms->rp_state.rp_thread_created = false;