From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:60544) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gw3Ub-0002h9-2o for qemu-devel@nongnu.org; Tue, 19 Feb 2019 06:23:17 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gw3Ua-0001L8-Bf for qemu-devel@nongnu.org; Tue, 19 Feb 2019 06:23:17 -0500 Date: Tue, 19 Feb 2019 12:23:08 +0100 From: Kevin Wolf Message-ID: <20190219112308.GI4727@localhost.localdomain> References: <20190218161822.3573-1-kwolf@redhat.com> <20190218161822.3573-12-kwolf@redhat.com> <3efe273b-16af-4927-b684-57cf71275923@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3efe273b-16af-4927-b684-57cf71275923@redhat.com> Subject: Re: [Qemu-devel] [PATCH 11/12] block: Use normal drain for bdrv_set_aio_context() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: qemu-block@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, berrange@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org Am 18.02.2019 um 21:57 hat Eric Blake geschrieben: > On 2/18/19 10:18 AM, Kevin Wolf wrote: > > Now that bdrv_set_aio_context() works inside drained sections, it can > > also use the real drain function instead of open coding something > > similar. > > > > Signed-off-by: Kevin Wolf > > --- > > block.c | 14 +++++--------- > > 1 file changed, 5 insertions(+), 9 deletions(-) > > > > diff --git a/block.c b/block.c > > index aefb5701f5..7024172db8 100644 > > --- a/block.c > > +++ b/block.c > > @@ -5268,18 +5268,15 @@ void bdrv_attach_aio_context(BlockDriverState *bs, > > bs->walking_aio_notifiers = false; > > } > > > > +/* The caller must own the AioContext lock for the old AioContext of bs, but it > > + * must not own the AioContext lock for new_context. */ > > Is this comment still accurate, given > > > void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) > > { > > - AioContext *ctx = bdrv_get_aio_context(bs); > > - > > - if (ctx == new_context) { > > + if (bdrv_get_aio_context(bs) == new_context) { > > return; > > } > > the short-circuiting when the old context is the new context? Hm, yes, old == new is an exception where you quite obviously can't have old locked and new unlocked at the same time. So is adding this enough? (unless new_context is the same as the current context of bs) Kevin