From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39104) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cxush-00041b-Nl for qemu-devel@nongnu.org; Tue, 11 Apr 2017 08:26:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cxusg-0003oz-Os for qemu-devel@nongnu.org; Tue, 11 Apr 2017 08:26:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35369) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cxusg-0003nl-Ig for qemu-devel@nongnu.org; Tue, 11 Apr 2017 08:26:46 -0400 From: Fam Zheng Date: Tue, 11 Apr 2017 20:26:23 +0800 Message-Id: <20170411122632.14050-3-famz@redhat.com> In-Reply-To: <20170411122632.14050-1-famz@redhat.com> References: <20170411122632.14050-1-famz@redhat.com> Subject: [Qemu-devel] [PULL 02/11] block: Quiesce old aio context during bdrv_set_aio_context List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , famz@redhat.com The fact that the bs->aio_context is changing can confuse the dataplane iothread, because of the now fine granularity aio context lock. bdrv_drain should rather be a bdrv_drained_begin/end pair, but since bs->aio_context is changing, we can just use aio_disable_external and bdrv_parent_drained_begin. Reported-by: Ed Swierk Signed-off-by: Fam Zheng Acked-by: Stefan Hajnoczi Reviewed-by: Stefan Hajnoczi Reviewed-by: Kevin Wolf --- block.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index b8a3011..a995a8e 100644 --- a/block.c +++ b/block.c @@ -4396,11 +4396,12 @@ void bdrv_attach_aio_context(BlockDriverState *bs, void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) { - AioContext *ctx; + AioContext *ctx = bdrv_get_aio_context(bs); + aio_disable_external(ctx); + bdrv_parent_drained_begin(bs); bdrv_drain(bs); /* ensure there are no in-flight requests */ - ctx = bdrv_get_aio_context(bs); while (aio_poll(ctx, false)) { /* wait for all bottom halves to execute */ } @@ -4412,6 +4413,8 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) */ aio_context_acquire(new_context); bdrv_attach_aio_context(bs, new_context); + bdrv_parent_drained_end(bs); + aio_enable_external(ctx); aio_context_release(new_context); } -- 2.9.3