From: Vladimir Sementsov-Ogievskiy Date: Wed, 21 Oct 2020 14:58:41 +0000 (+0300) Subject: block/io: split out bdrv_find_conflicting_request X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=3183937ff943f0bd0c43bb2625be1a040677ce25;p=qmiga%2Fqemu.git block/io: split out bdrv_find_conflicting_request To be reused in separate. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Stefan Hajnoczi Message-Id: <20201021145859.11201-4-vsementsov@virtuozzo.com> Signed-off-by: Max Reitz --- diff --git a/block/io.c b/block/io.c index 27370107b2..640136b8bc 100644 --- a/block/io.c +++ b/block/io.c @@ -754,43 +754,54 @@ 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; }