3.16.66-rc1 review patch. If anyone has any objections, please let me know.
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From: Gabriel Krisman Bertazi krisman@linux.vnet.ibm.com
commit 2c5d16d6a9e7218e57b716e4fd9d77c776d21471 upstream.
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 Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/scsi/sd.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -192,6 +192,7 @@ cache_type_store(struct device *dev, str 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)) {