From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51976) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fUxHU-0004x0-Cv for qemu-devel@nongnu.org; Mon, 18 Jun 2018 12:45:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fUxHT-0006KT-9q for qemu-devel@nongnu.org; Mon, 18 Jun 2018 12:45:28 -0400 From: Kevin Wolf Date: Mon, 18 Jun 2018 18:44:45 +0200 Message-Id: <20180618164504.24488-17-kwolf@redhat.com> In-Reply-To: <20180618164504.24488-1-kwolf@redhat.com> References: <20180618164504.24488-1-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 16/35] block: Allow AIO_WAIT_WHILE with NULL ctx List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org bdrv_drain_all() wants to have a single polling loop for draining the in-flight requests of all nodes. This means that the AIO_WAIT_WHILE() condition relies on activity in multiple AioContexts, which is polled from the mainloop context. We must therefore call AIO_WAIT_WHILE() from the mainloop thread and use the AioWait notification mechanism. Just randomly picking the AioContext of any non-mainloop thread would work, but instead of bothering to find such a context in the caller, we can just as well accept NULL for ctx. Signed-off-by: Kevin Wolf --- include/block/aio-wait.h | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h index 783d3678dd..c85a62f798 100644 --- a/include/block/aio-wait.h +++ b/include/block/aio-wait.h @@ -57,7 +57,8 @@ typedef struct { /** * AIO_WAIT_WHILE: * @wait: the aio wait object - * @ctx: the aio context + * @ctx: the aio context, or NULL if multiple aio contexts (for which the + * caller does not hold a lock) are involved in the polling condition. * @cond: wait while this conditional expression is true * * Wait while a condition is true. Use this to implement synchronous @@ -75,7 +76,7 @@ typedef struct { bool waited_ = false; \ AioWait *wait_ = (wait); \ AioContext *ctx_ = (ctx); \ - if (in_aio_context_home_thread(ctx_)) { \ + if (ctx_ && in_aio_context_home_thread(ctx_)) { \ while ((cond)) { \ aio_poll(ctx_, true); \ waited_ = true; \ @@ -86,9 +87,13 @@ typedef struct { /* Increment wait_->num_waiters before evaluating cond. */ \ atomic_inc(&wait_->num_waiters); \ while ((cond)) { \ - aio_context_release(ctx_); \ + if (ctx_) { \ + aio_context_release(ctx_); \ + } \ aio_poll(qemu_get_aio_context(), true); \ - aio_context_acquire(ctx_); \ + if (ctx_) { \ + aio_context_acquire(ctx_); \ + } \ waited_ = true; \ } \ atomic_dec(&wait_->num_waiters); \ -- 2.13.6