On Sun, Apr 25, 2021 at 08:02:10PM -0700, Bart Van Assche wrote: > On 4/25/21 1:57 AM, Ming Lei wrote: > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > > index c289991ffaed..7cbaee282b6d 100644 > > --- a/drivers/scsi/scsi_lib.c > > +++ b/drivers/scsi/scsi_lib.c > > @@ -1568,7 +1568,11 @@ static void scsi_mq_done(struct scsi_cmnd *cmd) > > if (unlikely(test_and_set_bit(SCMD_STATE_COMPLETE, &cmd->state))) > > return; > > trace_scsi_dispatch_cmd_done(cmd); > > - blk_mq_complete_request(cmd->request); > > + > > + if (unlikely(host_byte(cmd->result) != DID_OK)) > > + blk_mq_complete_request_locally(cmd->request); > > + else > > + blk_mq_complete_request(cmd->request); > > } > > This change is so tricky that it deserves a comment. > > An even better approach would be *not* to export > blk_mq_complete_request_locally() from the block layer to block drivers > and instead modify the block layer such that it completes a request on > the same CPU if request completion happens from inside the context of a > tag iteration function. That would save driver writers the trouble of > learning yet another block layer API. Yeah, that is possible, and one request flag(eg. RQF_ITERATED) can be added. The flag is set before calling ->fn(), and evaluated in blk_mq_complete_request_remote(). Thanks, Ming
