From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zhong Subject: [PATCH scsi] Short the path length of scsi_cmd_to_driver() Date: Thu, 27 Sep 2012 17:51:35 +0800 Message-ID: <1348739495.3596.55.camel@ThinkPad-T420> References: <1348464626.2475.13.camel@ThinkPad-T420> <1348465493.2467.3.camel@dabdike> <1348470210.2475.47.camel@ThinkPad-T420> <1348472104.2467.8.camel@dabdike> <1348721055.2509.0.camel@dabdike> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1348721055.2509.0.camel@dabdike> Sender: linux-kernel-owner@vger.kernel.org To: James Bottomley Cc: "Martin K. Petersen" , LKML , linux-scsi@vger.kernel.org, "Paul E. McKenney" List-Id: linux-scsi@vger.kernel.org Hi James, Martin, Here is the updated version, please help to review. Thanks, Zhong ======== As suggested by James: this patch tries to short the path length of scsi_cmd_to_driver(). As only REQ_TYPE_BLOCK_PC commands can be submitted without a driver, so we could avoid the related NULL checking, as long as we make sure we don't use it for REQ_TYPE_BLOCK_PC type commands. Plus, this fixes a bug where you get different behaviors from REQ_TYPE_BLOCK_PC commands when a driver is and isn't attached. And Martin pointed out that we could have eh action be triggered for REQ_TYPE_FS type only. Signed-off-by: Li Zhong --- drivers/scsi/scsi_error.c | 8 +++++--- include/scsi/scsi_cmnd.h | 12 ++---------- 2 files changed, 7 insertions(+), 13 deletions(-) diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index de2337f..4001559 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -789,7 +789,6 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd, int cmnd_size, int timeout, unsigned sense_bytes) { struct scsi_device *sdev = scmd->device; - struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd); struct Scsi_Host *shost = sdev->host; DECLARE_COMPLETION_ONSTACK(done); unsigned long timeleft; @@ -845,8 +844,11 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd, scsi_eh_restore_cmnd(scmd, &ses); - if (sdrv && sdrv->eh_action) - rtn = sdrv->eh_action(scmd, cmnd, cmnd_size, rtn); + if (scmd->request->cmd_type == REQ_TYPE_FS) { + struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd); + if (sdrv->eh_action) + rtn = sdrv->eh_action(scmd, cmnd, cmnd_size, rtn); + } return rtn; } diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h index ac06cc5..de5f5d8 100644 --- a/include/scsi/scsi_cmnd.h +++ b/include/scsi/scsi_cmnd.h @@ -132,18 +132,10 @@ struct scsi_cmnd { unsigned char tag; /* SCSI-II queued command tag */ }; +/* make sure not to use it with REQ_TYPE_BLOCK_PC commands */ static inline struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd) { - struct scsi_driver **sdp; - - if (!cmd->request->rq_disk) - return NULL; - - sdp = (struct scsi_driver **)cmd->request->rq_disk->private_data; - if (!sdp) - return NULL; - - return *sdp; + return *(struct scsi_driver **)cmd->request->rq_disk->private_data; } extern struct scsi_cmnd *scsi_get_command(struct scsi_device *, gfp_t); -- 1.7.7.6