| Message ID | 1446228283-32627-1-git-send-email-krisman@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
>>>>> "Gabriel" == Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com> writes:
Gabriel> This patch clears the PS bit in the buffer returned by Mode
Gabriel> Select, right before it is used in the Mode Select command.
Applied.
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 3f37022..f724777 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -204,6 +204,7 @@ cache_type_store(struct device *dev, struct device_attribute *attr, buffer_data[2] &= ~0x05; buffer_data[2] |= wce << 2 | rcd; sp = buffer_data[0] & 0x80 ? 1 : 0; + buffer_data[0] &= ~0x80; if (scsi_mode_select(sdp, 1, sp, 8, buffer_data, len, SD_TIMEOUT, SD_MAX_RETRIES, &data, &sshdr)) {
According to SPC-4, in a Mode Select, the PS bit in Mode Pages is reserved and must be set to 0 by the driver. In the sd implementation, function cache_type_store does a Mode Sense, which might set the PS bit on the read buffer, followed by a Mode Select, which receives the same buffer, without explicitly clearing the PS bit. So, in cases where target supports saving the Mode Page to a non-volatile location, we end up doing a Mode Select with the PS bit set, which could cause an illegal request error if the target is checking this. This was observed on a new firmware change, which was subsequently reverted, but this changes sd.c to be more compliant with SPC-4. This patch clears the PS bit in the buffer returned by Mode Select, right before it is used in the Mode Select command. Signed-off-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com> --- drivers/scsi/sd.c | 1 + 1 file changed, 1 insertion(+)