From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Bart Van Assche To: "ming.lei@redhat.com" CC: "hch@lst.de" , "linux-block@vger.kernel.org" , "jthumshirn@suse.de" , "stern@rowland.harvard.edu" , "axboe@kernel.dk" , "jianchao.w.wang@oracle.com" Subject: Re: [PATCH v5 1/9] block: Change the preempt-only flag into a counter Date: Wed, 8 Aug 2018 15:27:31 +0000 Message-ID: References: <20180807225133.27221-1-bart.vanassche@wdc.com> <20180807225133.27221-2-bart.vanassche@wdc.com> <20180808082136.GA13518@ming.t460p> In-Reply-To: <20180808082136.GA13518@ming.t460p> Content-Type: text/plain; charset="utf-7" MIME-Version: 1.0 List-ID: On Wed, 2018-08-08 at 16:21 +-0800, Ming Lei wrote: +AD4- On Tue, Aug 07, 2018 at 03:51:25PM -0700, Bart Van Assche wrote: +AD4- +AD4- The RQF+AF8-PREEMPT flag is used for three purposes: +AD4- +AD4- - In the SCSI core, for making sure that power management reque= sts +AD4- +AD4- are executed if a device is in the +ACI-quiesced+ACI- state. +AD4- +AD4- - For domain validation by SCSI drivers that use the parallel p= ort. +AD4- +AD4- - In the IDE driver, for IDE preempt requests. +AD4-=20 +AD4- I think the above description may not be accurate, BLK+AF8-MQ+AF8-REQ= +AF8-PREEMPT is +AD4- always set inside scsi+AF8-execute(), that means any scsi+AF8-execute= () callers +AD4- can use the flag of RQF+AF8-PREEMPT, of course, not limited to the ab= ove +AD4- three cases. Hello Ming, What I described is for which cases we really need the RQF+AF8-PREEMPT flag= rather than in which cases the RQF+AF8-PREEMPT flag is set today. I think we shoul= d split the RQF+AF8-PREEMPT flag into three flags, one flag per case mentioned abov= e. Bart.