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a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1695058113; 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=bYUP+MM7SbKNQ/UCCiBh+qINj5V/1DPeXsfFNDPnhCI=; b=WIVrlYDh392+YtzQqJnxvB1dfHQ23bAbv7ODqgVMGOIg4mgBUaUdlAuDEMDdgX02cnaih5 3bNBlgWoAF/QtvBA== From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: Juan Quintela , Peter Xu , Stefan Hajnoczi , Leonardo Bras Subject: [PATCH 4/8] migration: Fix possible race when shutting down to_dst_file Date: Mon, 18 Sep 2023 14:28:18 -0300 Message-Id: <20230918172822.19052-5-farosas@suse.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230918172822.19052-1-farosas@suse.de> References: <20230918172822.19052-1-farosas@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @suse.de) X-ZM-MESSAGEID: 1695058205381100001 Content-Type: text/plain; charset="utf-8" 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 15b7258bb2..6e09463466 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1246,7 +1246,7 @@ static void migrate_fd_error(MigrationState *s, const= Error *error) static void migrate_fd_cancel(MigrationState *s) { int old_state ; - QEMUFile *f =3D migrate_get_current()->to_dst_file; + trace_migrate_fd_cancel(); =20 WITH_QEMU_LOCK_GUARD(&s->qemu_file_lock) { @@ -1272,11 +1272,13 @@ 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 =3D=3D MIGRATION_STATUS_CANCELLING && f) { - qemu_file_shutdown(f); + if (s->state =3D=3D 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 =3D=3D MIGRATION_STATUS_CANCELLING && s->block_inactive) { Error *local_err =3D NULL; @@ -1536,12 +1538,14 @@ void qmp_migrate_pause(Error **errp) { MigrationState *ms =3D migrate_get_current(); MigrationIncomingState *mis =3D migration_incoming_get_current(); - int ret; + int ret =3D 0; =20 if (ms->state =3D=3D MIGRATION_STATUS_POSTCOPY_ACTIVE) { /* Source side, during postcopy */ qemu_mutex_lock(&ms->qemu_file_lock); - ret =3D qemu_file_shutdown(ms->to_dst_file); + if (ms->to_dst_file) { + ret =3D qemu_file_shutdown(ms->to_dst_file); + } qemu_mutex_unlock(&ms->qemu_file_lock); if (ret) { error_setg(errp, "Failed to pause source migration"); --=20 2.35.3