From patchwork Wed Aug 16 14:25:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabiano Rosas X-Patchwork-Id: 1821867 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=tKQIVJqG; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=5UWiSaje; 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 4RQr6p2XPwz1yNm for ; Thu, 17 Aug 2023 00:26:42 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qWHSb-0003r5-CZ; Wed, 16 Aug 2023 10:25:21 -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 1qWHSZ-0003q9-Sf for qemu-devel@nongnu.org; Wed, 16 Aug 2023 10:25:19 -0400 Received: from smtp-out2.suse.de ([2001:67c:2178:6::1d]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qWHSX-0003hr-Kx for qemu-devel@nongnu.org; Wed, 16 Aug 2023 10:25:19 -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-out2.suse.de (Postfix) with ESMTPS id 4EA6A1F855; Wed, 16 Aug 2023 14:25:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1692195916; 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=gQVDJc/VWRXwS0mHPY1vDLVZJ1suUUTu444PbUJHcVk=; b=tKQIVJqGxZv89oNmVijG07kInwgyCZOzsU0qi0tg8t2rvi80eTih2QkG/3o2rbIxOpvPP4 ikjrj5NE+IRy2voFIkmGfWoCrmsnflcGLaPPbx3hSHORVmrNdie05bv8vHfEkXQpfymqP/ Z0XMzQZdO2QLmylAbiRhYFHq4gLW1fI= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1692195916; 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=gQVDJc/VWRXwS0mHPY1vDLVZJ1suUUTu444PbUJHcVk=; b=5UWiSajevqu0V9GEfwgqMtrtPnfSMH0Zyg7+1kGpHgM2YrkF1/YGyAaPuG7L8IGHfy6kY9 I+RXnAOYbzgzUBCQ== 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 C0649133F2; Wed, 16 Aug 2023 14:25:14 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id cLDWIUrc3GShdwAAMHmgww (envelope-from ); Wed, 16 Aug 2023 14:25:14 +0000 From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: Juan Quintela , Peter Xu , Wei Wang , Leonardo Bras Subject: [PATCH v4 1/8] migration: Fix possible race when setting rp_state.error Date: Wed, 16 Aug 2023 11:25:03 -0300 Message-Id: <20230816142510.5637-2-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=2001:67c:2178:6::1d; envelope-from=farosas@suse.de; helo=smtp-out2.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 don't need to set the rp_state.error right after a shutdown because qemu_file_shutdown() always sets the QEMUFile error, so the return path thread would have seen it and set the rp error itself. Setting the error outside of the thread is also racy because the thread could clear it after we set it. Reviewed-by: Peter Xu Signed-off-by: Fabiano Rosas --- migration/migration.c | 1 - 1 file changed, 1 deletion(-) diff --git a/migration/migration.c b/migration/migration.c index 5528acb65e..f88c86079c 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -2062,7 +2062,6 @@ static int await_return_path_close_on_source(MigrationState *ms) * waiting for the destination. */ qemu_file_shutdown(ms->rp_state.from_dst_file); - mark_source_rp_bad(ms); } trace_await_return_path_close_on_source_joining(); qemu_thread_join(&ms->rp_state.rp_thread); 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; 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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; From patchwork Wed Aug 16 14:25:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabiano Rosas X-Patchwork-Id: 1821876 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=lzdBD6gx; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=TeyIGGw7; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; 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Wed, 16 Aug 2023 10:25:23 -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-out2.suse.de (Postfix) with ESMTPS id 3EE161F855; Wed, 16 Aug 2023 14:25:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1692195920; 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=ratvuBX3qQ91vHO0LxE42YTYPtTJVqto9t43u0ml8kE=; b=lzdBD6gxI2H03t6dQDGa000JhHQ2b9JxjfhiORu/sfTI48C1HG8jqs+K4xnC2VEKf091U4 4ZIy7e7QPSuzXMy16TxM3sFulrU606t2XICrHu5bZ3e7EakoD63iqzPCaSpzTqcqUkMbg9 jaB02JzK5J1fFG6m9sZQxG+8znMQBX0= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1692195920; 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=ratvuBX3qQ91vHO0LxE42YTYPtTJVqto9t43u0ml8kE=; b=TeyIGGw7cw/31LkRsvTOIEm91RQI4QtRVnopNeBTYOBIlAhX5mFyEeyhHK1iWWAmcrltdQ TBO/OJZ1cxpCOdDg== 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 B7F44133F2; Wed, 16 Aug 2023 14:25:18 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id yLL7H07c3GShdwAAMHmgww (envelope-from ); Wed, 16 Aug 2023 14:25:18 +0000 From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: Juan Quintela , Peter Xu , Wei Wang , Leonardo Bras Subject: [PATCH v4 3/8] migration: Fix possible race when shutting down to_dst_file Date: Wed, 16 Aug 2023 11:25:05 -0300 Message-Id: <20230816142510.5637-4-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=2001:67c:2178:6::1d; envelope-from=farosas@suse.de; helo=smtp-out2.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 It's not safe to call qemu_file_shutdown() on the to_dst_file without first checking for the file's presence under the lock. The cleanup of this file happens at postcopy_pause() and migrate_fd_cleanup() which are not necessarily running in the same thread as migrate_fd_cancel(). Reviewed-by: Peter Xu Signed-off-by: Fabiano Rosas --- migration/migration.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 85c171f32c..5e6a766235 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1245,7 +1245,7 @@ static void migrate_fd_error(MigrationState *s, const Error *error) static void migrate_fd_cancel(MigrationState *s) { int old_state ; - QEMUFile *f = migrate_get_current()->to_dst_file; + trace_migrate_fd_cancel(); WITH_QEMU_LOCK_GUARD(&s->qemu_file_lock) { @@ -1271,11 +1271,13 @@ static void migrate_fd_cancel(MigrationState *s) * If we're unlucky the migration code might be stuck somewhere in a * send/write while the network has failed and is waiting to timeout; * if we've got shutdown(2) available then we can force it to quit. - * The outgoing qemu file gets closed in migrate_fd_cleanup that is - * called in a bh, so there is no race against this cancel. */ - if (s->state == MIGRATION_STATUS_CANCELLING && f) { - qemu_file_shutdown(f); + if (s->state == MIGRATION_STATUS_CANCELLING) { + WITH_QEMU_LOCK_GUARD(&s->qemu_file_lock) { + if (s->to_dst_file) { + qemu_file_shutdown(s->to_dst_file); + } + } } if (s->state == MIGRATION_STATUS_CANCELLING && s->block_inactive) { Error *local_err = NULL; @@ -1519,12 +1521,14 @@ void qmp_migrate_pause(Error **errp) { MigrationState *ms = migrate_get_current(); MigrationIncomingState *mis = migration_incoming_get_current(); - int ret; + int ret = 0; if (ms->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) { /* Source side, during postcopy */ qemu_mutex_lock(&ms->qemu_file_lock); - ret = qemu_file_shutdown(ms->to_dst_file); + if (ms->to_dst_file) { + ret = qemu_file_shutdown(ms->to_dst_file); + } qemu_mutex_unlock(&ms->qemu_file_lock); if (ret) { error_setg(errp, "Failed to pause source migration"); From patchwork Wed Aug 16 14:25:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabiano Rosas X-Patchwork-Id: 1821874 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; 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Reviewed-by: Peter Xu Signed-off-by: Fabiano Rosas --- migration/migration.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 5e6a766235..195726eb4a 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1177,12 +1177,6 @@ static void migrate_fd_cleanup(MigrationState *s) qemu_fclose(tmp); } - if (s->postcopy_qemufile_src) { - migration_ioc_unregister_yank_from_file(s->postcopy_qemufile_src); - qemu_fclose(s->postcopy_qemufile_src); - s->postcopy_qemufile_src = NULL; - } - assert(!migration_is_active(s)); if (s->state == MIGRATION_STATUS_CANCELLING) { From patchwork Wed Aug 16 14:25:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabiano Rosas X-Patchwork-Id: 1821868 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; 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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'll start calling the await_return_path_close_on_source() function from other parts of the code, so move all of the related checks and tracepoints into it. Reviewed-by: Peter Xu Signed-off-by: Fabiano Rosas --- migration/migration.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 195726eb4a..4edbee3a5d 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -2049,6 +2049,14 @@ static int open_return_path_on_source(MigrationState *ms, /* Returns 0 if the RP was ok, otherwise there was an error on the RP */ static int await_return_path_close_on_source(MigrationState *ms) { + int ret; + + if (!ms->rp_state.rp_thread_created) { + return 0; + } + + trace_migration_return_path_end_before(); + /* * 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 @@ -2066,7 +2074,10 @@ static int await_return_path_close_on_source(MigrationState *ms) qemu_thread_join(&ms->rp_state.rp_thread); ms->rp_state.rp_thread_created = false; trace_await_return_path_close_on_source_close(); - return ms->rp_state.error; + + ret = ms->rp_state.error; + trace_migration_return_path_end_after(ret); + return ret; } static inline void @@ -2362,20 +2373,8 @@ static void migration_completion(MigrationState *s) goto fail; } - /* - * If rp was opened we must clean up the thread before - * cleaning everything else up (since if there are no failures - * it will wait for the destination to send it's status in - * a SHUT command). - */ - if (s->rp_state.rp_thread_created) { - int rp_error; - trace_migration_return_path_end_before(); - rp_error = await_return_path_close_on_source(s); - trace_migration_return_path_end_after(rp_error); - if (rp_error) { - goto fail; - } + if (await_return_path_close_on_source(s)) { + goto fail; } if (qemu_file_get_error(s->to_dst_file)) { From patchwork Wed Aug 16 14:25:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabiano Rosas X-Patchwork-Id: 1821869 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; 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envelope-from=farosas@suse.de; helo=smtp-out2.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 Replace the return path retry logic with finishing and restarting the thread. This fixes a race when resuming the migration that leads to a segfault. Currently when doing postcopy we consider that an IO error on the return path file could be due to a network intermittency. We then keep the thread alive but have it do cleanup of the 'from_dst_file' and wait on the 'postcopy_pause_rp' semaphore. When the user issues a migrate resume, a new return path is opened and the thread is allowed to continue. There's a race condition in the above mechanism. It is possible for the new return path file to be setup *before* the cleanup code in the return path thread has had a chance to run, leading to the *new* file being closed and the pointer set to NULL. When the thread is released after the resume, it tries to dereference 'from_dst_file' and crashes: Thread 7 "return path" received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7fffd1dbf700 (LWP 9611)] 0x00005555560e4893 in qemu_file_get_error_obj (f=0x0, errp=0x0) at ../migration/qemu-file.c:154 154 return f->last_error; (gdb) bt #0 0x00005555560e4893 in qemu_file_get_error_obj (f=0x0, errp=0x0) at ../migration/qemu-file.c:154 #1 0x00005555560e4983 in qemu_file_get_error (f=0x0) at ../migration/qemu-file.c:206 #2 0x0000555555b9a1df in source_return_path_thread (opaque=0x555556e06000) at ../migration/migration.c:1876 #3 0x000055555602e14f in qemu_thread_start (args=0x55555782e780) at ../util/qemu-thread-posix.c:541 #4 0x00007ffff38d76ea in start_thread (arg=0x7fffd1dbf700) at pthread_create.c:477 #5 0x00007ffff35efa6f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Here's the race (important bit is open_return_path happening before migration_release_dst_files): migration | qmp | return path --------------------------+-----------------------------+--------------------------------- qmp_migrate_pause() shutdown(ms->to_dst_file) f->last_error = -EIO migrate_detect_error() postcopy_pause() set_state(PAUSED) wait(postcopy_pause_sem) qmp_migrate(resume) migrate_fd_connect() resume = state == PAUSED open_return_path <-- TOO SOON! set_state(RECOVER) post(postcopy_pause_sem) (incoming closes to_src_file) res = qemu_file_get_error(rp) migration_release_dst_files() ms->rp_state.from_dst_file = NULL post(postcopy_pause_rp_sem) postcopy_pause_return_path_thread() wait(postcopy_pause_rp_sem) rp = ms->rp_state.from_dst_file goto retry qemu_file_get_error(rp) SIGSEGV ------------------------------------------------------------------------------------------- We can keep the retry logic without having the thread alive and waiting. The only piece of data used by it is the 'from_dst_file' and it is only allowed to proceed after a migrate resume is issued and the semaphore released at migrate_fd_connect(). Move the retry logic to outside the thread by waiting for the thread to finish before pausing the migration. Reviewed-by: Peter Xu Signed-off-by: Fabiano Rosas --- migration/migration.c | 60 ++++++++----------------------------------- migration/migration.h | 1 - 2 files changed, 11 insertions(+), 50 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 4edbee3a5d..7dfcbc3634 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1775,18 +1775,6 @@ static void migrate_handle_rp_req_pages(MigrationState *ms, const char* rbname, } } -/* Return true to retry, false to quit */ -static bool postcopy_pause_return_path_thread(MigrationState *s) -{ - trace_postcopy_pause_return_path(); - - qemu_sem_wait(&s->postcopy_pause_rp_sem); - - trace_postcopy_pause_return_path_continued(); - - return true; -} - static int migrate_handle_rp_recv_bitmap(MigrationState *s, char *block_name) { RAMBlock *block = qemu_ram_block_by_name(block_name); @@ -1870,7 +1858,6 @@ static void *source_return_path_thread(void *opaque) trace_source_return_path_thread_entry(); rcu_register_thread(); -retry: while (!ms->rp_state.error && !qemu_file_get_error(rp) && migration_is_setup_or_active(ms->state)) { trace_source_return_path_thread_loop_top(); @@ -1992,26 +1979,7 @@ retry: } out: - res = qemu_file_get_error(rp); - if (res) { - if (res && migration_in_postcopy()) { - /* - * Maybe there is something we can do: it looks like a - * network down issue, and we pause for a recovery. - */ - migration_release_dst_files(ms); - rp = NULL; - if (postcopy_pause_return_path_thread(ms)) { - /* - * Reload rp, reset the rest. Referencing it is safe since - * it's reset only by us above, or when migration completes - */ - rp = ms->rp_state.from_dst_file; - ms->rp_state.error = false; - goto retry; - } - } - + if (qemu_file_get_error(rp)) { trace_source_return_path_thread_bad_end(); mark_source_rp_bad(ms); } @@ -2022,8 +1990,7 @@ out: return NULL; } -static int open_return_path_on_source(MigrationState *ms, - bool create_thread) +static int open_return_path_on_source(MigrationState *ms) { ms->rp_state.from_dst_file = qemu_file_get_return_path(ms->to_dst_file); if (!ms->rp_state.from_dst_file) { @@ -2032,11 +1999,6 @@ static int open_return_path_on_source(MigrationState *ms, trace_open_return_path_on_source(); - if (!create_thread) { - /* We're done */ - return 0; - } - qemu_thread_create(&ms->rp_state.rp_thread, "return path", source_return_path_thread, ms, QEMU_THREAD_JOINABLE); ms->rp_state.rp_thread_created = true; @@ -2076,6 +2038,7 @@ static int await_return_path_close_on_source(MigrationState *ms) trace_await_return_path_close_on_source_close(); ret = ms->rp_state.error; + ms->rp_state.error = false; trace_migration_return_path_end_after(ret); return ret; } @@ -2551,6 +2514,13 @@ static MigThrError postcopy_pause(MigrationState *s) qemu_file_shutdown(file); qemu_fclose(file); + /* + * We're already pausing, so ignore any errors on the return + * path and just wait for the thread to finish. It will be + * re-created when we resume. + */ + await_return_path_close_on_source(s); + migrate_set_state(&s->state, s->state, MIGRATION_STATUS_POSTCOPY_PAUSED); @@ -2568,12 +2538,6 @@ static MigThrError postcopy_pause(MigrationState *s) if (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER) { /* Woken up by a recover procedure. Give it a shot */ - /* - * Firstly, let's wake up the return path now, with a new - * return path channel. - */ - qemu_sem_post(&s->postcopy_pause_rp_sem); - /* Do the resume logic */ if (postcopy_do_resume(s) == 0) { /* Let's continue! */ @@ -3263,7 +3227,7 @@ void migrate_fd_connect(MigrationState *s, Error *error_in) * QEMU uses the return path. */ if (migrate_postcopy_ram() || migrate_return_path()) { - if (open_return_path_on_source(s, !resume)) { + if (open_return_path_on_source(s)) { error_setg(&local_err, "Unable to open return-path for postcopy"); migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED); migrate_set_error(s, local_err); @@ -3327,7 +3291,6 @@ static void migration_instance_finalize(Object *obj) qemu_sem_destroy(&ms->rate_limit_sem); qemu_sem_destroy(&ms->pause_sem); qemu_sem_destroy(&ms->postcopy_pause_sem); - qemu_sem_destroy(&ms->postcopy_pause_rp_sem); qemu_sem_destroy(&ms->rp_state.rp_sem); qemu_sem_destroy(&ms->rp_state.rp_pong_acks); qemu_sem_destroy(&ms->postcopy_qemufile_src_sem); @@ -3347,7 +3310,6 @@ static void migration_instance_init(Object *obj) migrate_params_init(&ms->parameters); qemu_sem_init(&ms->postcopy_pause_sem, 0); - qemu_sem_init(&ms->postcopy_pause_rp_sem, 0); qemu_sem_init(&ms->rp_state.rp_sem, 0); qemu_sem_init(&ms->rp_state.rp_pong_acks, 0); qemu_sem_init(&ms->rate_limit_sem, 0); diff --git a/migration/migration.h b/migration/migration.h index 6eea18db36..36eb5ba70b 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -382,7 +382,6 @@ struct MigrationState { /* Needed by postcopy-pause state */ QemuSemaphore postcopy_pause_sem; - QemuSemaphore postcopy_pause_rp_sem; /* * Whether we abort the migration if decompression errors are * detected at the destination. It is left at false for qemu From patchwork Wed Aug 16 14:25:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabiano Rosas X-Patchwork-Id: 1821871 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=sXKigsg0; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=V8ENgObP; 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 4RQr8m4vTfz1yXY for ; Thu, 17 Aug 2023 00:28:24 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qWHSm-0004Ei-Fh; Wed, 16 Aug 2023 10:25:32 -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 1qWHSl-0004CZ-Jq for qemu-devel@nongnu.org; Wed, 16 Aug 2023 10:25:31 -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 1qWHSj-0003nr-3U for qemu-devel@nongnu.org; Wed, 16 Aug 2023 10:25:31 -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 0EB85211AE; Wed, 16 Aug 2023 14:25:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1692195928; 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=DGhGE717fUJFvyUY5vhbyY/GLiHbUzH5b0cd6j63xVg=; b=sXKigsg0Uvi1sIiHxKJHLSbbF7vU2X2kJf+2VuxA70kHbsVO0K1pSHMNgXA2hh1Yfoe20J IE1uisSmeNC4+uHkf40hsqBUg2xLtGzKOvLMXgCU/u13gDuCeubi6WrhgoglnH9EJejCxo FnEHJ822ZelwZh6Vt2705LHEnV7N0YQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1692195928; 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=DGhGE717fUJFvyUY5vhbyY/GLiHbUzH5b0cd6j63xVg=; b=V8ENgObPzOl/SoSeAfxbcbekXhazIcjgw/bjbVHQvVTxxACIsoj6sNFEkVkAxvC+ZlJsTS thu0aElSUSzma1BQ== 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 8402C133F2; Wed, 16 Aug 2023 14:25:26 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id kLekE1bc3GShdwAAMHmgww (envelope-from ); Wed, 16 Aug 2023 14:25:26 +0000 From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: Juan Quintela , Peter Xu , Wei Wang , Leonardo Bras Subject: [PATCH v4 7/8] migration: Move return path cleanup to main migration thread Date: Wed, 16 Aug 2023 11:25:09 -0300 Message-Id: <20230816142510.5637-8-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 Now that the return path thread is allowed to finish during a paused migration, we can move the cleanup of the QEMUFiles to the main migration thread. Reviewed-by: Peter Xu Signed-off-by: Fabiano Rosas --- migration/migration.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/migration/migration.c b/migration/migration.c index 7dfcbc3634..7fec57ad7f 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -98,6 +98,7 @@ static int migration_maybe_pause(MigrationState *s, int *current_active_state, int new_state); static void migrate_fd_cancel(MigrationState *s); +static int await_return_path_close_on_source(MigrationState *s); static bool migration_needs_multiple_sockets(void) { @@ -1177,6 +1178,12 @@ static void migrate_fd_cleanup(MigrationState *s) qemu_fclose(tmp); } + /* + * We already cleaned up to_dst_file, so errors from the return + * path might be due to that, ignore them. + */ + await_return_path_close_on_source(s); + assert(!migration_is_active(s)); if (s->state == MIGRATION_STATUS_CANCELLING) { @@ -1985,7 +1992,6 @@ out: } trace_source_return_path_thread_end(); - migration_release_dst_files(ms); rcu_unregister_thread(); return NULL; } @@ -2039,6 +2045,9 @@ static int await_return_path_close_on_source(MigrationState *ms) ret = ms->rp_state.error; ms->rp_state.error = false; + + migration_release_dst_files(ms); + trace_migration_return_path_end_after(ret); return ret; } From patchwork Wed Aug 16 14:25:10 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabiano Rosas X-Patchwork-Id: 1821866 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=YjqeTTZe; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=jEaURBvw; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; 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bh=9t0NjDORWhTRZt2oEHyswwgUTKKL0BZEn6qCStJ0d2w=; b=jEaURBvwpJySjtdmN3usxPYz3Z7758KYOnoIp3AhotHiMnilMSfuXHoNA5cZW/lVnHDLe7 WwVw39XtRDUT8gDA== 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 77331133F2; Wed, 16 Aug 2023 14:25:28 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id aGGAEFjc3GShdwAAMHmgww (envelope-from ); Wed, 16 Aug 2023 14:25:28 +0000 From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: Juan Quintela , Peter Xu , Wei Wang , Leonardo Bras Subject: [PATCH v4 8/8] migration: Add a wrapper to cleanup migration files Date: Wed, 16 Aug 2023 11:25:10 -0300 Message-Id: <20230816142510.5637-9-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=195.135.220.29; envelope-from=farosas@suse.de; helo=smtp-out2.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 currently have a pattern for cleaning up a migration QEMUFile: qemu_mutex_lock(&s->qemu_file_lock); file = s->file_name; s->file_name = NULL; qemu_mutex_unlock(&s->qemu_file_lock); migration_ioc_unregister_yank_from_file(file); qemu_file_shutdown(file); qemu_fclose(file); There are some considerations for this sequence: - we must clear the pointer under the lock, to avoid TOC/TOU bugs; - the close() and yank unregister expect be given a non-null parameter; - a close() in one thread should not race with a shutdown() in another; - we don't need to shutdown() right before close(); Create a wrapper function to make sure everything works correctly. Note: the return path didn't have a yank handler registered, I added it nonetheless for uniformity. Signed-off-by: Fabiano Rosas --- migration/migration.c | 91 +++++++++++++------------------------------ 1 file changed, 27 insertions(+), 64 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 7fec57ad7f..22ab7199e4 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -217,6 +217,26 @@ MigrationIncomingState *migration_incoming_get_current(void) return current_incoming; } +static void migration_file_release(QEMUFile **file) +{ + MigrationState *ms = migrate_get_current(); + QEMUFile *tmp; + + /* + * Reset the pointer before releasing it to avoid holding the lock + * for too long. + */ + WITH_QEMU_LOCK_GUARD(&ms->qemu_file_lock) { + tmp = *file; + *file = NULL; + } + + if (tmp) { + migration_ioc_unregister_yank_from_file(tmp); + qemu_fclose(tmp); + } +} + void migration_incoming_transport_cleanup(MigrationIncomingState *mis) { if (mis->socket_address_list) { @@ -1155,8 +1175,6 @@ static void migrate_fd_cleanup(MigrationState *s) qemu_savevm_state_cleanup(); if (s->to_dst_file) { - QEMUFile *tmp; - trace_migrate_fd_cleanup(); qemu_mutex_unlock_iothread(); if (s->migration_thread_running) { @@ -1166,16 +1184,7 @@ static void migrate_fd_cleanup(MigrationState *s) qemu_mutex_lock_iothread(); multifd_save_cleanup(); - qemu_mutex_lock(&s->qemu_file_lock); - tmp = s->to_dst_file; - s->to_dst_file = NULL; - qemu_mutex_unlock(&s->qemu_file_lock); - /* - * Close the file handle without the lock to make sure the - * critical section won't block for long. - */ - migration_ioc_unregister_yank_from_file(tmp); - qemu_fclose(tmp); + migration_file_release(&s->to_dst_file); } /* @@ -1815,38 +1824,6 @@ static int migrate_handle_rp_resume_ack(MigrationState *s, uint32_t value) return 0; } -/* - * Release ms->rp_state.from_dst_file (and postcopy_qemufile_src if - * existed) in a safe way. - */ -static void migration_release_dst_files(MigrationState *ms) -{ - QEMUFile *file; - - WITH_QEMU_LOCK_GUARD(&ms->qemu_file_lock) { - /* - * Reset the from_dst_file pointer first before releasing it, as we - * can't block within lock section - */ - file = ms->rp_state.from_dst_file; - ms->rp_state.from_dst_file = NULL; - } - - /* - * Do the same to postcopy fast path socket too if there is. No - * locking needed because this qemufile should only be managed by - * return path thread. - */ - if (ms->postcopy_qemufile_src) { - migration_ioc_unregister_yank_from_file(ms->postcopy_qemufile_src); - qemu_file_shutdown(ms->postcopy_qemufile_src); - qemu_fclose(ms->postcopy_qemufile_src); - ms->postcopy_qemufile_src = NULL; - } - - qemu_fclose(file); -} - /* * Handles messages sent on the return path towards the source VM * @@ -2003,6 +1980,8 @@ static int open_return_path_on_source(MigrationState *ms) return -1; } + migration_ioc_register_yank(qemu_file_get_ioc(ms->rp_state.from_dst_file)); + trace_open_return_path_on_source(); qemu_thread_create(&ms->rp_state.rp_thread, "return path", @@ -2046,7 +2025,8 @@ static int await_return_path_close_on_source(MigrationState *ms) ret = ms->rp_state.error; ms->rp_state.error = false; - migration_release_dst_files(ms); + migration_file_release(&ms->rp_state.from_dst_file); + migration_file_release(&ms->postcopy_qemufile_src); trace_migration_return_path_end_after(ret); return ret; @@ -2502,26 +2482,9 @@ static MigThrError postcopy_pause(MigrationState *s) assert(s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE); while (true) { - QEMUFile *file; - - /* - * Current channel is possibly broken. Release it. Note that this is - * guaranteed even without lock because to_dst_file should only be - * modified by the migration thread. That also guarantees that the - * unregister of yank is safe too without the lock. It should be safe - * even to be within the qemu_file_lock, but we didn't do that to avoid - * taking more mutex (yank_lock) within qemu_file_lock. TL;DR: we make - * the qemu_file_lock critical section as small as possible. - */ + /* Current channel is possibly broken. Release it. */ assert(s->to_dst_file); - migration_ioc_unregister_yank_from_file(s->to_dst_file); - qemu_mutex_lock(&s->qemu_file_lock); - file = s->to_dst_file; - s->to_dst_file = NULL; - qemu_mutex_unlock(&s->qemu_file_lock); - - qemu_file_shutdown(file); - qemu_fclose(file); + migration_file_release(&s->to_dst_file); /* * We're already pausing, so ignore any errors on the return