[SCSI] sd: retry read_capacity on UNIT_ATTENTION
Hazard testing uncovered yet another bug in sd. Under heavy reset
activity the retry counter might be exhausted and the command will be
returned with sense UNIT_ATTENTION/0x29/00 (POWER ON, RESET, OR BUS
DEVICE RESET OCCURRED). In those cases we should just increase the
retry counter again, retrying one more to clear up this Unit Attention
state.
[jejb: update to work with RC16 devices and not to loop endlessly]
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 7955bc2..015a597 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1433,6 +1433,8 @@
#error RC16_LEN must not be more than SD_BUF_SIZE
#endif
+#define READ_CAPACITY_RETRIES_ON_RESET 10
+
static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp,
unsigned char *buffer)
{
@@ -1440,7 +1442,7 @@
struct scsi_sense_hdr sshdr;
int sense_valid = 0;
int the_result;
- int retries = 3;
+ int retries = 3, reset_retries = READ_CAPACITY_RETRIES_ON_RESET;
unsigned int alignment;
unsigned long long lba;
unsigned sector_size;
@@ -1469,6 +1471,13 @@
* Invalid Field in CDB, just retry
* silently with RC10 */
return -EINVAL;
+ if (sense_valid &&
+ sshdr.sense_key == UNIT_ATTENTION &&
+ sshdr.asc == 0x29 && sshdr.ascq == 0x00)
+ /* Device reset might occur several times,
+ * give it one more chance */
+ if (--reset_retries > 0)
+ continue;
}
retries--;
@@ -1527,7 +1536,7 @@
struct scsi_sense_hdr sshdr;
int sense_valid = 0;
int the_result;
- int retries = 3;
+ int retries = 3, reset_retries = READ_CAPACITY_RETRIES_ON_RESET;
sector_t lba;
unsigned sector_size;
@@ -1543,8 +1552,16 @@
if (media_not_present(sdkp, &sshdr))
return -ENODEV;
- if (the_result)
+ if (the_result) {
sense_valid = scsi_sense_valid(&sshdr);
+ if (sense_valid &&
+ sshdr.sense_key == UNIT_ATTENTION &&
+ sshdr.asc == 0x29 && sshdr.ascq == 0x00)
+ /* Device reset might occur several times,
+ * give it one more chance */
+ if (--reset_retries > 0)
+ continue;
+ }
retries--;
} while (the_result && retries);