ata: libata-scsi: Fix CDL control

Delete extra checks for the ATA_DFLAG_CDL_ENABLED flag that prevent
SET FEATURES command from being issued to a drive when NCQ commands
are active.

ata_mselect_control_ata_feature() sets / clears the ATA_DFLAG_CDL_ENABLED
flag during the translation of MODE SELECT to SET FEATURES. If SET FEATURES
gets deferred due to outstanding NCQ commands, the original MODE SELECT
command will be re-queued. When the re-queued MODE SELECT goes through
the ata_mselect_control_ata_feature() translation again, SET FEATURES
will not be issued because ATA_DFLAG_CDL_ENABLED has been already set or
cleared by the initial translation of MODE SELECT.

The ATA_DFLAG_CDL_ENABLED checks in ata_mselect_control_ata_feature()
are safe to remove because scsi_cdl_enable() implements a similar logic
that avoids enabling CDL if it has been enabled already.

Fixes: 17e897a45675 ("ata: libata-scsi: Improve CDL control")
Cc: stable@vger.kernel.org
Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 57f674f51b0cea86f21b7a5361c4828876e91c9c..2ded5e476d6e69350fedd2aaa7443b83c433035a 100644 (file)
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3904,21 +3904,16 @@ static int ata_mselect_control_ata_feature(struct ata_queued_cmd *qc,
        /* Check cdl_ctrl */
        switch (buf[0] & 0x03) {
        case 0:
-               /* Disable CDL if it is enabled */
-               if (!(dev->flags & ATA_DFLAG_CDL_ENABLED))
-                       return 0;
+               /* Disable CDL */
                ata_dev_dbg(dev, "Disabling CDL\n");
                cdl_action = 0;
                dev->flags &= ~ATA_DFLAG_CDL_ENABLED;
                break;
        case 0x02:
                /*
-                * Enable CDL if not already enabled. Since this is mutually
-                * exclusive with NCQ priority, allow this only if NCQ priority
-                * is disabled.
+                * Enable CDL. Since CDL is mutually exclusive with NCQ
+                * priority, allow this only if NCQ priority is disabled.
                 */
-               if (dev->flags & ATA_DFLAG_CDL_ENABLED)
-                       return 0;
                if (dev->flags & ATA_DFLAG_NCQ_PRIO_ENABLED) {
                        ata_dev_err(dev,
                                "NCQ priority must be disabled to enable CDL\n");