@@ -707,26 +707,23 @@ void scsi_cdl_check(struct scsi_device *sdev)
*/
int scsi_cdl_enable(struct scsi_device *sdev, bool enable)
{
- struct scsi_mode_data data;
- struct scsi_sense_hdr sshdr;
- struct scsi_vpd *vpd;
- bool is_ata = false;
char buf[64];
+ bool is_ata;
int ret;
if (!sdev->cdl_supported)
return -EOPNOTSUPP;
rcu_read_lock();
- vpd = rcu_dereference(sdev->vpd_pg89);
- if (vpd)
- is_ata = true;
+ is_ata = rcu_dereference(sdev->vpd_pg89);
rcu_read_unlock();
/*
* For ATA devices, CDL needs to be enabled with a SET FEATURES command.
*/
if (is_ata) {
+ struct scsi_mode_data data;
+ struct scsi_sense_hdr sshdr;
char *buf_data;
int len;
@@ -735,16 +732,30 @@ int scsi_cdl_enable(struct scsi_device *sdev, bool enable)
if (ret)
return -EINVAL;
- /* Enable CDL using the ATA feature page */
+ /* Enable or disable CDL using the ATA feature page */
len = min_t(size_t, sizeof(buf),
data.length - data.header_length -
data.block_descriptor_length);
buf_data = buf + data.header_length +
data.block_descriptor_length;
- if (enable)
- buf_data[4] = 0x02;
- else
- buf_data[4] = 0;
+
+ /*
+ * If we want to enable CDL and CDL is already enabled on the
+ * device, do nothing. This avoids needlessly resetting the CDL
+ * statistics on the device as that is implied by the CDL enable
+ * action. Similar to this, there is no need to do anything if
+ * we want to disable CDL and CDL is already disabled.
+ */
+ if (enable) {
+ if ((buf_data[4] & 0x03) == 0x02)
+ goto out;
+ buf_data[4] &= ~0x03;
+ buf_data[4] |= 0x02;
+ } else {
+ if ((buf_data[4] & 0x03) == 0x00)
+ goto out;
+ buf_data[4] &= ~0x03;
+ }
ret = scsi_mode_select(sdev, 1, 0, buf_data, len, 5 * HZ, 3,
&data, &sshdr);
@@ -756,6 +767,7 @@ int scsi_cdl_enable(struct scsi_device *sdev, bool enable)
}
}
+out:
sdev->cdl_enable = enable;
return 0;
With ATA devices supporting the CDL feature, using CDL requires that the feature be enabled with a SET FEATURES command. This command is issued as the translated command for the MODE SELECT command issued by scsi_cdl_enable() when the user enables CDL through the device cdl_enable sysfs attribute. However, the implementation of scsi_cdl_enable() always issues a MODE SELECT command for ATA devices when the enable argument is true, even if CDL is already enabled on the device. While this does not cause any issue with using CDL descriptors with read/write commands (the CDL feature will be enabled on the drive), issuing the MODE SELECT command even when the device CDL feature is already enabled will cause a reset of the ATA device CDL statistics log page (as defined in ACS, any CDL enable action must reset the device statistics). Avoid this needless actions (and the implied statistics log page reset) by modifying scsi_cdl_enable() to issue the MODE SELECT command to enable CDL if and only if CDL is not reported as already enabled on the device. And while at it, simplify the initialization of the is_ata boolean variable and move the declaration of the scsi mode data and sense header variables to within the scope of ATA device handling. Fixes: 1b22cfb14142 ("scsi: core: Allow enabling and disabling command duration limits") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Niklas Cassel <cassel@kernel.org> Reviewed-by: Igor Pylypiv <ipylypiv@google.com> --- drivers/scsi/scsi.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-)