From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lei Subject: Re: [PATCH V2] blk-mq: introduce BLK_STS_DEV_RESOURCE Date: Tue, 23 Jan 2018 22:27:10 +0800 Message-ID: <20180123142709.GC9792@ming.t460p> References: <20180123105611.7389-1-ming.lei@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-block-owner@vger.kernel.org To: "Martin K. Petersen" Cc: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig , Mike Snitzer , dm-devel@redhat.com, Laurence Oberman , Bart Van Assche List-Id: dm-devel.ids Hello Martin, On Tue, Jan 23, 2018 at 08:30:41AM -0500, Martin K. Petersen wrote: > > Ming, > > > + * Block layer and block driver specific status, which is ususally returnd > ^^^^^^^ > > + * from driver to block layer in IO path. > > Given that the comment blurb is long and the flag not defined until > later, it is not entirely obvious that you are documenting > BLK_STS_DEV_RESOURCE. So please make that clear at the beginning of the > comment. OK, how about the following document? /* * BLK_STS_DEV_RESOURC: Block layer and block driver specific status, * which is usually returned from driver to block layer in IO path. * * BLK_STS_DEV_RESOURCE is returned from driver to block layer if device * related resource is run out of, but driver can guarantee that queue * will be rerun in future for dispatching the current request when this * resource is available. * * Difference with BLK_STS_RESOURCE: * If driver isn't sure if the queue can be run again for dealing with the * current request after this kind of resource is available, please return * BLK_STS_SOURCE, for example, when memory allocation, DMA Mapping or other * system resource allocation fails and IO can't be submitted to device, * BLK_STS_RESOURCE should be used for avoiding IO hang. */ #define BLK_STS_DEV_RESOURCE ((__force blk_status_t)13) Thanks, Ming