From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57332) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YuPtf-0003lS-97 for qemu-devel@nongnu.org; Mon, 18 May 2015 14:36:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YuPte-0000df-6S for qemu-devel@nongnu.org; Mon, 18 May 2015 14:36:15 -0400 Message-ID: <555A30F4.7030207@redhat.com> Date: Mon, 18 May 2015 20:35:32 +0200 From: Max Reitz MIME-Version: 1.0 References: <1431669868-26804-1-git-send-email-famz@redhat.com> <1431669868-26804-7-git-send-email-famz@redhat.com> In-Reply-To: <1431669868-26804-7-git-send-email-famz@redhat.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit 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: Fam Zheng , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, jcody@redhat.com, armbru@redhat.com, Stefan Hajnoczi , pbonzini@redhat.com 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... Max