From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48368) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YuXEZ-0005cg-4b for qemu-devel@nongnu.org; Mon, 18 May 2015 22:26:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YuXEY-0000ua-Av for qemu-devel@nongnu.org; Mon, 18 May 2015 22:26:19 -0400 Date: Tue, 19 May 2015 10:26:08 +0800 From: Fam Zheng Message-ID: <20150519022608.GA9804@ad.nay.redhat.com> References: <1431669868-26804-1-git-send-email-famz@redhat.com> <1431669868-26804-7-git-send-email-famz@redhat.com> <555A30F4.7030207@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <555A30F4.7030207@redhat.com> Subject: Re: [Qemu-devel] [PATCH v3 06/12] nbd-server: Clear "can_read" when "device io" blocker is set List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz Cc: Kevin Wolf , qemu-block@nongnu.org, jcody@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com, Stefan Hajnoczi , pbonzini@redhat.com On Mon, 05/18 20:35, Max Reitz wrote: > On 15.05.2015 08:04, Fam Zheng wrote: > >So that NBD export cannot submit IO during bdrv_drain_all(). > > > >Signed-off-by: Fam Zheng > >--- > > nbd.c | 18 ++++++++++++++++++ > > 1 file changed, 18 insertions(+) > > But can_read is not cleared until nbd_update_can_read() is called, which is > only in nbd_request_get(), nbd_request_put(), and nbd_co_receive_request(), > which are all called from nbd_trip() - so the one request which clears > can_read will most probably be itself processed. > > Maybe we should call nbd_update_can_read() in nbd_op_blocker_changed(), for > all clients of the export? Or just once somewhere at the beginning of > processing a request, and if io_blocked is set, just yield... I think you're right. I'll fix that. Fam