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Fri, 9 Oct 2020 06:34:39 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-182.ams2.redhat.com [10.36.112.182]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7062160BFA; Fri, 9 Oct 2020 06:34:39 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 2A5AE112993C; Fri, 9 Oct 2020 08:34:33 +0200 (CEST) From: Markus Armbruster To: qemu-devel@nongnu.org Subject: [PULL 12/14] block: Add bdrv_co_enter()/leave() Date: Fri, 9 Oct 2020 08:34:30 +0200 Message-Id: <20201009063432.303441-13-armbru@redhat.com> In-Reply-To: <20201009063432.303441-1-armbru@redhat.com> References: <20201009063432.303441-1-armbru@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/09 02:34:37 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [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, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Kevin Wolf Add a pair of functions to temporarily move the current coroutine to the AioContext of a given BlockDriverState. Signed-off-by: Kevin Wolf Message-Id: <20201005155855.256490-13-kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi Signed-off-by: Markus Armbruster --- include/block/block.h | 17 +++++++++++++++++ block.c | 23 +++++++++++++++++++++++ 2 files changed, 40 insertions(+) diff --git a/include/block/block.h b/include/block/block.h index ce2ac39299..1027c58a41 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -640,6 +640,23 @@ bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag); */ AioContext *bdrv_get_aio_context(BlockDriverState *bs); +/** + * Move the current coroutine to the AioContext of @bs and return the old + * AioContext of the coroutine. Increase bs->in_flight so that draining @bs + * will wait for the operation to proceed until the corresponding + * bdrv_co_leave(). + * + * Consequently, you can't call drain inside a bdrv_co_enter/leave() section as + * this will deadlock. + */ +AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs); + +/** + * Ends a section started by bdrv_co_enter(). Move the current coroutine back + * to old_ctx and decrease bs->in_flight again. + */ +void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx); + /** * Transfer control to @co in the aio context of @bs */ diff --git a/block.c b/block.c index 52b2e2709f..8d9b9017d3 100644 --- a/block.c +++ b/block.c @@ -6303,6 +6303,29 @@ AioContext *bdrv_get_aio_context(BlockDriverState *bs) return bs ? bs->aio_context : qemu_get_aio_context(); } +AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs) +{ + Coroutine *self = qemu_coroutine_self(); + AioContext *old_ctx = qemu_coroutine_get_aio_context(self); + AioContext *new_ctx; + + /* + * Increase bs->in_flight to ensure that this operation is completed before + * moving the node to a different AioContext. Read new_ctx only afterwards. + */ + bdrv_inc_in_flight(bs); + + new_ctx = bdrv_get_aio_context(bs); + aio_co_reschedule_self(new_ctx); + return old_ctx; +} + +void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx) +{ + aio_co_reschedule_self(old_ctx); + bdrv_dec_in_flight(bs); +} + void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co) { aio_co_enter(bdrv_get_aio_context(bs), co);