From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45403) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1euHwU-00019F-5s for qemu-devel@nongnu.org; Fri, 09 Mar 2018 08:20:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1euHwT-0007Vt-7a for qemu-devel@nongnu.org; Fri, 09 Mar 2018 08:20:14 -0500 From: Stefan Hajnoczi Date: Fri, 9 Mar 2018 13:19:46 +0000 Message-Id: <20180309131949.18640-5-stefanha@redhat.com> In-Reply-To: <20180309131949.18640-1-stefanha@redhat.com> References: <20180309131949.18640-1-stefanha@redhat.com> Subject: [Qemu-devel] [PULL 4/7] block: add aio_wait_bh_oneshot() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Stefan Hajnoczi , Peter Crosthwaite , Peter Maydell , Kevin Wolf , Paolo Bonzini , qemu-block@nongnu.org, Fam Zheng , "Michael S. Tsirkin" , Max Reitz , Richard Henderson Sometimes it's necessary for the main loop thread to run a BH in an IOThread and wait for its completion. This primitive is useful during startup/shutdown to synchronize and avoid race conditions. Signed-off-by: Stefan Hajnoczi Reviewed-by: Fam Zheng Acked-by: Paolo Bonzini Message-id: 20180307144205.20619-2-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- include/block/aio-wait.h | 13 +++++++++++++ util/aio-wait.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+) diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h index a48c744fa8..f7a3972200 100644 --- a/include/block/aio-wait.h +++ b/include/block/aio-wait.h @@ -113,4 +113,17 @@ typedef struct { */ void aio_wait_kick(AioWait *wait); +/** + * aio_wait_bh_oneshot: + * @ctx: the aio context + * @cb: the BH callback function + * @opaque: user data for the BH callback function + * + * Run a BH in @ctx and wait for it to complete. + * + * Must be called from the main loop thread with @ctx acquired exactly once. + * Note that main loop event processing may occur. + */ +void aio_wait_bh_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque); + #endif /* QEMU_AIO_WAIT */ diff --git a/util/aio-wait.c b/util/aio-wait.c index a487cdb852..975afddf4c 100644 --- a/util/aio-wait.c +++ b/util/aio-wait.c @@ -38,3 +38,34 @@ void aio_wait_kick(AioWait *wait) aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL); } } + +typedef struct { + AioWait wait; + bool done; + QEMUBHFunc *cb; + void *opaque; +} AioWaitBHData; + +/* Context: BH in IOThread */ +static void aio_wait_bh(void *opaque) +{ + AioWaitBHData *data = opaque; + + data->cb(data->opaque); + + data->done = true; + aio_wait_kick(&data->wait); +} + +void aio_wait_bh_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque) +{ + AioWaitBHData data = { + .cb = cb, + .opaque = opaque, + }; + + assert(qemu_get_current_aio_context() == qemu_get_aio_context()); + + aio_bh_schedule_oneshot(ctx, aio_wait_bh, &data); + AIO_WAIT_WHILE(&data.wait, ctx, !data.done); +} -- 2.14.3