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Wed, 21 Oct 2020 14:59:15 +0000 From: Vladimir Sementsov-Ogievskiy To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, vsementsov@virtuozzo.com, eblake@redhat.com, armbru@redhat.com, fam@euphon.net, stefanha@redhat.com, mreitz@redhat.com, kwolf@redhat.com, den@virtuozzo.com Subject: [PATCH v7 03/21] block/io: split out bdrv_find_conflicting_request Date: Wed, 21 Oct 2020 17:58:41 +0300 Message-Id: <20201021145859.11201-4-vsementsov@virtuozzo.com> X-Mailer: git-send-email 2.21.3 In-Reply-To: <20201021145859.11201-1-vsementsov@virtuozzo.com> References: <20201021145859.11201-1-vsementsov@virtuozzo.com> X-Originating-IP: [185.215.60.82] X-ClientProxiedBy: AM0PR03CA0091.eurprd03.prod.outlook.com (2603:10a6:208:69::32) To AM7PR08MB5494.eurprd08.prod.outlook.com (2603:10a6:20b:dc::15) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from kvm.sw.ru (185.215.60.82) by AM0PR03CA0091.eurprd03.prod.outlook.com (2603:10a6:208:69::32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.18 via Frontend Transport; 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envelope-from=vsementsov@virtuozzo.com; helo=EUR05-DB8-obe.outbound.protection.outlook.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/21 10:59:20 X-ACL-Warn: Detected OS = Windows NT kernel [generic] [fuzzy] 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" To be reused in separate. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Stefan Hajnoczi --- block/io.c | 71 +++++++++++++++++++++++++++++++----------------------- 1 file changed, 41 insertions(+), 30 deletions(-) diff --git a/block/io.c b/block/io.c index bf6d4d5e77..c2d9b1f849 100644 --- a/block/io.c +++ b/block/io.c @@ -728,43 +728,54 @@ static bool tracked_request_overlaps(BdrvTrackedRequest *req, return true; } +/* Called with self->bs->reqs_lock held */ +static BdrvTrackedRequest * +bdrv_find_conflicting_request(BdrvTrackedRequest *self) +{ + BdrvTrackedRequest *req; + + QLIST_FOREACH(req, &self->bs->tracked_requests, list) { + if (req == self || (!req->serialising && !self->serialising)) { + continue; + } + if (tracked_request_overlaps(req, self->overlap_offset, + self->overlap_bytes)) + { + /* + * Hitting this means there was a reentrant request, for + * example, a block driver issuing nested requests. This must + * never happen since it means deadlock. + */ + assert(qemu_coroutine_self() != req->co); + + /* + * If the request is already (indirectly) waiting for us, or + * will wait for us as soon as it wakes up, then just go on + * (instead of producing a deadlock in the former case). + */ + if (!req->waiting_for) { + return req; + } + } + } + + return NULL; +} + static bool coroutine_fn bdrv_wait_serialising_requests_locked(BlockDriverState *bs, BdrvTrackedRequest *self) { BdrvTrackedRequest *req; - bool retry; bool waited = false; - do { - retry = false; - QLIST_FOREACH(req, &bs->tracked_requests, list) { - if (req == self || (!req->serialising && !self->serialising)) { - continue; - } - if (tracked_request_overlaps(req, self->overlap_offset, - self->overlap_bytes)) - { - /* Hitting this means there was a reentrant request, for - * example, a block driver issuing nested requests. This must - * never happen since it means deadlock. - */ - assert(qemu_coroutine_self() != req->co); - - /* If the request is already (indirectly) waiting for us, or - * will wait for us as soon as it wakes up, then just go on - * (instead of producing a deadlock in the former case). */ - if (!req->waiting_for) { - self->waiting_for = req; - qemu_co_queue_wait(&req->wait_queue, &bs->reqs_lock); - self->waiting_for = NULL; - retry = true; - waited = true; - break; - } - } - } - } while (retry); + while ((req = bdrv_find_conflicting_request(self))) { + self->waiting_for = req; + qemu_co_queue_wait(&req->wait_queue, &bs->reqs_lock); + self->waiting_for = NULL; + waited = true; + } + return waited; }