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Fri, 16 Apr 2021 08:09:30 +0000 From: Vladimir Sementsov-Ogievskiy To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, vsementsov@virtuozzo.com, eblake@redhat.com, mreitz@redhat.com, kwolf@redhat.com, rvkagan@yandex-team.ru, den@openvz.org Subject: [PATCH v3 03/33] block/nbd: ensure ->connection_thread is always valid Date: Fri, 16 Apr 2021 11:08:41 +0300 Message-Id: <20210416080911.83197-4-vsementsov@virtuozzo.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210416080911.83197-1-vsementsov@virtuozzo.com> References: <20210416080911.83197-1-vsementsov@virtuozzo.com> X-Originating-IP: [185.215.60.206] X-ClientProxiedBy: HE1P189CA0030.EURP189.PROD.OUTLOOK.COM (2603:10a6:7:53::43) To AM7PR08MB5494.eurprd08.prod.outlook.com (2603:10a6:20b:dc::15) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from localhost.localdomain (185.215.60.206) by HE1P189CA0030.EURP189.PROD.OUTLOOK.COM (2603:10a6:7:53::43) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4042.16 via Frontend Transport; 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envelope-from=vsementsov@virtuozzo.com; helo=EUR04-VI1-obe.outbound.protection.outlook.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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MSGID_FROM_MTA_HEADER=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_PASS=-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: 2.1.23 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" From: Roman Kagan Simplify lifetime management of BDRVNBDState->connect_thread by delaying the possible cleanup of it until the BDRVNBDState itself goes away. This also reverts 0267101af6 "block/nbd: fix possible use after free of s->connect_thread" as now s->connect_thread can't be cleared until the very end. Signed-off-by: Roman Kagan [vsementsov: rebase, revert 0267101af6 changes] Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Eric Blake --- block/nbd.c | 56 ++++++++++++++++++++--------------------------------- 1 file changed, 21 insertions(+), 35 deletions(-) diff --git a/block/nbd.c b/block/nbd.c index a407a3814b..272af60b44 100644 --- a/block/nbd.c +++ b/block/nbd.c @@ -144,17 +144,31 @@ typedef struct BDRVNBDState { NBDConnectThread *connect_thread; } BDRVNBDState; +static void nbd_free_connect_thread(NBDConnectThread *thr); static int nbd_establish_connection(BlockDriverState *bs, SocketAddress *saddr, Error **errp); static int nbd_co_establish_connection(BlockDriverState *bs, Error **errp); -static void nbd_co_establish_connection_cancel(BlockDriverState *bs, - bool detach); +static void nbd_co_establish_connection_cancel(BlockDriverState *bs); static int nbd_client_handshake(BlockDriverState *bs, Error **errp); static void nbd_yank(void *opaque); static void nbd_clear_bdrvstate(BlockDriverState *bs) { BDRVNBDState *s = (BDRVNBDState *)bs->opaque; + NBDConnectThread *thr = s->connect_thread; + bool thr_running; + + qemu_mutex_lock(&thr->mutex); + thr_running = thr->state == CONNECT_THREAD_RUNNING; + if (thr_running) { + thr->state = CONNECT_THREAD_RUNNING_DETACHED; + } + qemu_mutex_unlock(&thr->mutex); + + /* the runaway thread will clean it up itself */ + if (!thr_running) { + nbd_free_connect_thread(thr); + } yank_unregister_instance(BLOCKDEV_YANK_INSTANCE(bs->node_name)); @@ -297,7 +311,7 @@ static void coroutine_fn nbd_client_co_drain_begin(BlockDriverState *bs) qemu_co_sleep_wake(s->connection_co_sleep_ns_state); } - nbd_co_establish_connection_cancel(bs, false); + nbd_co_establish_connection_cancel(bs); reconnect_delay_timer_del(s); @@ -337,7 +351,7 @@ static void nbd_teardown_connection(BlockDriverState *bs) if (s->connection_co_sleep_ns_state) { qemu_co_sleep_wake(s->connection_co_sleep_ns_state); } - nbd_co_establish_connection_cancel(bs, true); + nbd_co_establish_connection_cancel(bs); } if (qemu_in_coroutine()) { s->teardown_co = qemu_coroutine_self(); @@ -448,11 +462,6 @@ nbd_co_establish_connection(BlockDriverState *bs, Error **errp) BDRVNBDState *s = bs->opaque; NBDConnectThread *thr = s->connect_thread; - if (!thr) { - /* detached */ - return -1; - } - qemu_mutex_lock(&thr->mutex); switch (thr->state) { @@ -496,12 +505,6 @@ nbd_co_establish_connection(BlockDriverState *bs, Error **errp) s->wait_connect = true; qemu_coroutine_yield(); - if (!s->connect_thread) { - /* detached */ - return -1; - } - assert(thr == s->connect_thread); - qemu_mutex_lock(&thr->mutex); switch (thr->state) { @@ -549,18 +552,12 @@ nbd_co_establish_connection(BlockDriverState *bs, Error **errp) * nbd_co_establish_connection_cancel * Cancel nbd_co_establish_connection asynchronously: it will finish soon, to * allow drained section to begin. - * - * If detach is true, also cleanup the state (or if thread is running, move it - * to CONNECT_THREAD_RUNNING_DETACHED state). s->connect_thread becomes NULL if - * detach is true. */ -static void nbd_co_establish_connection_cancel(BlockDriverState *bs, - bool detach) +static void nbd_co_establish_connection_cancel(BlockDriverState *bs) { BDRVNBDState *s = bs->opaque; NBDConnectThread *thr = s->connect_thread; bool wake = false; - bool do_free = false; qemu_mutex_lock(&thr->mutex); @@ -571,21 +568,10 @@ static void nbd_co_establish_connection_cancel(BlockDriverState *bs, s->wait_connect = false; wake = true; } - if (detach) { - thr->state = CONNECT_THREAD_RUNNING_DETACHED; - s->connect_thread = NULL; - } - } else if (detach) { - do_free = true; } qemu_mutex_unlock(&thr->mutex); - if (do_free) { - nbd_free_connect_thread(thr); - s->connect_thread = NULL; - } - if (wake) { aio_co_wake(s->connection_co); } @@ -2306,6 +2292,8 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags, goto fail; } + nbd_init_connect_thread(s); + /* * establish TCP connection, return error if it fails * TODO: Configurable retry-until-timeout behaviour. @@ -2322,8 +2310,6 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags, /* successfully connected */ s->state = NBD_CLIENT_CONNECTED; - nbd_init_connect_thread(s); - s->connection_co = qemu_coroutine_create(nbd_connection_entry, s); bdrv_inc_in_flight(bs); aio_co_schedule(bdrv_get_aio_context(bs), s->connection_co);