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| author | Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com> | 2015-10-30 16:04:43 -0200 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2015-11-11 21:10:26 -0500 |
| commit | 2c5d16d6a9e7218e57b716e4fd9d77c776d21471 (patch) | |
| tree | 801f68a3f47796dadb16521ee3a5776e4404f267 /drivers | |
| parent | 3467a1468fe00fe3f693907f01d980f62d1e46a3 (diff) | |
| download | lwn-2c5d16d6a9e7218e57b716e4fd9d77c776d21471.tar.gz lwn-2c5d16d6a9e7218e57b716e4fd9d77c776d21471.zip | |
sd: Clear PS bit before Mode Select.
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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/scsi/sd.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 3f370228bf31..f7247778c225 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)) { |