| Message ID | 20250403211937.2225615-2-bvanassche@acm.org |
|---|---|
| State | New |
| Headers | show |
| Series | Optimize the hot path in the UFS driver | expand |
On 03/04/2025 22:17, Bart Van Assche wrote: > /* Variant of blk_mq_rq_from_pdu() that verifies the type of its argument. */ > -static inline struct request *scsi_cmd_to_rq(struct scsi_cmnd *scmd) > -{ > - return blk_mq_rq_from_pdu(scmd); > -} > +#define scsi_cmd_to_rq(scmd) \ > + _Generic(scmd, \ > + const struct scsi_cmnd *: (const struct request *) \ > + blk_mq_rq_from_pdu((void *)scmd), \ > + struct scsi_cmnd *: blk_mq_rq_from_pdu((void *)scmd)) > > /* Out of curiosity, how this that better than this: static inline struct request *scsi_cmd_to_rq(const struct scsi_cmnd *scmd) { return blk_mq_rq_from_pdu((void *)scmd); }
On 4/4/25 3:39 AM, John Garry wrote: > On 03/04/2025 22:17, Bart Van Assche wrote: >> /* Variant of blk_mq_rq_from_pdu() that verifies the type of its >> argument. */ >> -static inline struct request *scsi_cmd_to_rq(struct scsi_cmnd *scmd) >> -{ >> - return blk_mq_rq_from_pdu(scmd); >> -} >> +#define scsi_cmd_to_rq(scmd) \ >> + _Generic(scmd, \ >> + const struct scsi_cmnd *: (const struct request *) \ >> + blk_mq_rq_from_pdu((void *)scmd), \ >> + struct scsi_cmnd *: blk_mq_rq_from_pdu((void *)scmd)) >> /* > > Out of curiosity, how this that better than this: > > static inline struct request *scsi_cmd_to_rq(const struct scsi_cmnd *scmd) > { > return blk_mq_rq_from_pdu((void *)scmd); > } Yikes. With the inline function variant constness can be removed silently as follows: const struct scsi_cmnd *scmd; struct request *rq = scsi_cmd_to_rq(scmd); With patch 01/24, the compiler will issue a warning for the above code. Bart.
diff --git a/drivers/scsi/scsi_logging.c b/drivers/scsi/scsi_logging.c index b02af340c2d3..5aaff629b999 100644 --- a/drivers/scsi/scsi_logging.c +++ b/drivers/scsi/scsi_logging.c @@ -28,7 +28,7 @@ static void scsi_log_release_buffer(char *bufptr) static inline const char *scmd_name(const struct scsi_cmnd *scmd) { - struct request *rq = scsi_cmd_to_rq((struct scsi_cmnd *)scmd); + const struct request *rq = scsi_cmd_to_rq(scmd); if (!rq->q || !rq->q->disk) return NULL; @@ -94,7 +94,7 @@ void scmd_printk(const char *level, const struct scsi_cmnd *scmd, if (!logbuf) return; off = sdev_format_header(logbuf, logbuf_len, scmd_name(scmd), - scsi_cmd_to_rq((struct scsi_cmnd *)scmd)->tag); + scsi_cmd_to_rq(scmd)->tag); if (off < logbuf_len) { va_start(args, fmt); off += vscnprintf(logbuf + off, logbuf_len - off, fmt, args); @@ -374,8 +374,8 @@ EXPORT_SYMBOL(__scsi_print_sense); void scsi_print_sense(const struct scsi_cmnd *cmd) { scsi_log_print_sense(cmd->device, scmd_name(cmd), - scsi_cmd_to_rq((struct scsi_cmnd *)cmd)->tag, - cmd->sense_buffer, SCSI_SENSE_BUFFERSIZE); + scsi_cmd_to_rq(cmd)->tag, cmd->sense_buffer, + SCSI_SENSE_BUFFERSIZE); } EXPORT_SYMBOL(scsi_print_sense); @@ -393,7 +393,7 @@ void scsi_print_result(const struct scsi_cmnd *cmd, const char *msg, return; off = sdev_format_header(logbuf, logbuf_len, scmd_name(cmd), - scsi_cmd_to_rq((struct scsi_cmnd *)cmd)->tag); + scsi_cmd_to_rq(cmd)->tag); if (off >= logbuf_len) goto out_printk; diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h index 8ecfb94049db..154fbb39ca0c 100644 --- a/include/scsi/scsi_cmnd.h +++ b/include/scsi/scsi_cmnd.h @@ -144,10 +144,11 @@ struct scsi_cmnd { }; /* Variant of blk_mq_rq_from_pdu() that verifies the type of its argument. */ -static inline struct request *scsi_cmd_to_rq(struct scsi_cmnd *scmd) -{ - return blk_mq_rq_from_pdu(scmd); -} +#define scsi_cmd_to_rq(scmd) \ + _Generic(scmd, \ + const struct scsi_cmnd *: (const struct request *) \ + blk_mq_rq_from_pdu((void *)scmd), \ + struct scsi_cmnd *: blk_mq_rq_from_pdu((void *)scmd)) /* * Return the driver private allocation behind the command.
Instead of requiring the caller to cast away constness, make scsi_cmd_to_rq() accept const arguments. Cc: Hannes Reinecke <hare@suse.de> Cc: John Garry <john.g.garry@oracle.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> --- drivers/scsi/scsi_logging.c | 10 +++++----- include/scsi/scsi_cmnd.h | 9 +++++---- 2 files changed, 10 insertions(+), 9 deletions(-)