scsi: replace sr_test_unit_ready() with scsi_test_unit_ready()

The usage of TUR has been confusing involving several different
commits updating different parts over time.  Currently, the only
differences between scsi_test_unit_ready() and sr_test_unit_ready()
are,

* scsi_test_unit_ready() also sets sdev->changed on NOT_READY.

* scsi_test_unit_ready() returns 0 if TUR ended with UNIT_ATTENTION or
  NOT_READY.

Due to the above two differences, sr is using its own
sr_test_unit_ready(), but sd - the sole user of the above extra
handling - doesn't even need them.

Where scsi_test_unit_ready() is used in sd_media_changed(), the code
is looking for device ready w/ media present state which is true iff
TUR succeeds w/o sense data or UA, and when the device is not ready
for whatever reason sd_media_changed() explicitly marks media as
missing so there's no reason to set sdev->changed automatically from
scsi_test_unit_ready() on NOT_READY.

Drop both special handlings from scsi_test_unit_ready(), which makes
it equivalant to sr_test_unit_ready(), and replace
sr_test_unit_ready() with scsi_test_unit_ready().  Also, drop the
unnecessary explicit NOT_READY check from sd_media_changed().
Checking return value is enough for testing device readiness.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

5 files changed, 6 insertions, 51 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index eafeeda6e194..13bf89145b18 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1984,8 +1984,7 @@ EXPORT_SYMBOL(scsi_mode_sense);
  *              in.
  *
  *      Returns zero if unsuccessful or an error if TUR failed.  For
- *      removable media, a return of NOT_READY or UNIT_ATTENTION is
- *      translated to success, with the ->changed flag updated.
+ *      removable media, UNIT_ATTENTION sets ->changed flag.
  **/
 int
 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
@@ -2012,16 +2011,6 @@ scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
         } while (scsi_sense_valid(sshdr) &&
                  sshdr->sense_key == UNIT_ATTENTION && --retries);
 
-        if (!sshdr)
-                /* could not allocate sense buffer, so can't process it */
-                return result;
-
-        if (sdev->removable && scsi_sense_valid(sshdr) &&
-            (sshdr->sense_key == UNIT_ATTENTION ||
-             sshdr->sense_key == NOT_READY)) {
-                sdev->changed = 1;
-                result = 0;
-        }
         if (!sshdr_external)
                 kfree(sshdr);
         return result;
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index b9ab3a590e4b..8d488a9fef00 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1045,15 +1045,7 @@ static int sd_media_changed(struct gendisk *disk)
                                               sshdr);
         }
 
-        /*
-         * Unable to test, unit probably not ready.   This usually
-         * means there is no disc in the drive.  Mark as changed,
-         * and we will figure it out later once the drive is
-         * available again.
-         */
-        if (retval || (scsi_sense_valid(sshdr) &&
-                       /* 0x3a is medium not present */
-                       sshdr->asc == 0x3a)) {
+        if (retval) {
                 set_media_not_present(sdkp);
                 retval = 1;
                 goto out;
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index c7e29bdec2cd..310b3fac6313 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -165,32 +165,6 @@ static void scsi_cd_put(struct scsi_cd *cd)
         mutex_unlock(&sr_ref_mutex);
 }
 
-/* identical to scsi_test_unit_ready except that it doesn't
- * eat the NOT_READY returns for removable media */
-int sr_test_unit_ready(struct scsi_device *sdev, struct scsi_sense_hdr *sshdr)
-{
-        int retries = MAX_RETRIES;
-        int the_result;
-        u8 cmd[] = {TEST_UNIT_READY, 0, 0, 0, 0, 0 };
-
-        /* issue TEST_UNIT_READY until the initial startup UNIT_ATTENTION
-         * conditions are gone, or a timeout happens
-         */
-        do {
-                the_result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL,
-                                              0, sshdr, SR_TIMEOUT,
-                                              retries--, NULL);
-                if (scsi_sense_valid(sshdr) &&
-                    sshdr->sense_key == UNIT_ATTENTION)
-                        sdev->changed = 1;
-
-        } while (retries > 0 &&
-                 (!scsi_status_is_good(the_result) ||
-                  (scsi_sense_valid(sshdr) &&
-                   sshdr->sense_key == UNIT_ATTENTION)));
-        return the_result;
-}
-
 /*
  * This function checks to see if the media has been changed in the
  * CDROM drive.  It is possible that we have already sensed a change,
@@ -213,7 +187,8 @@ static int sr_media_change(struct cdrom_device_info *cdi, int slot)
         }
 
         sshdr =  kzalloc(sizeof(*sshdr), GFP_KERNEL);
-        retval = sr_test_unit_ready(cd->device, sshdr);
+        retval = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES,
+                                      sshdr);
         /*
          * Media is considered to be present if TUR succeeds or fails with
          * sense data indicating something other than media-not-present
@@ -784,7 +759,7 @@ static void get_capabilities(struct scsi_cd *cd)
         }
 
         /* eat unit attentions */
-        sr_test_unit_ready(cd->device, &sshdr);
+        scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);
 
         /* ask for mode page 0x2a */
         rc = scsi_mode_sense(cd->device, 0, 0x2a, buffer, 128,
diff --git a/drivers/scsi/sr.h b/drivers/scsi/sr.h
index 1e144dfdbd4b..81fbc0b78a52 100644
--- a/drivers/scsi/sr.h
+++ b/drivers/scsi/sr.h
@@ -61,7 +61,6 @@ int sr_select_speed(struct cdrom_device_info *cdi, int speed);
 int sr_audio_ioctl(struct cdrom_device_info *, unsigned int, void *);
 
 int sr_is_xa(Scsi_CD *);
-int sr_test_unit_ready(struct scsi_device *sdev, struct scsi_sense_hdr *sshdr);
 
 /* sr_vendor.c */
 void sr_vendor_init(Scsi_CD *);
diff --git a/drivers/scsi/sr_ioctl.c b/drivers/scsi/sr_ioctl.c
index 3cd8ffbad577..8be30554119b 100644
--- a/drivers/scsi/sr_ioctl.c
+++ b/drivers/scsi/sr_ioctl.c
@@ -307,7 +307,7 @@ int sr_drive_status(struct cdrom_device_info *cdi, int slot)
                 /* we have no changer support */
                 return -EINVAL;
         }
-        if (0 == sr_test_unit_ready(cd->device, &sshdr))
+        if (!scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr))
                 return CDS_DISC_OK;
 
         /* SK/ASC/ASCQ of 2/4/1 means "unit is becoming ready" */