[PATCH 4.9 02/80] target: Fix compare_and_write_callback handling for non GOOD status

From: Greg Kroah-Hartman
Date: Thu May 18 2017 - 07:32:10 EST

4.9-stable review patch. If anyone has any objections, please let me know.


From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

commit a71a5dc7f833943998e97ca8fa6a4c708a0ed1a9 upstream.

Following the bugfix for handling non SAM_STAT_GOOD COMPARE_AND_WRITE
status during COMMIT phase in commit 9b2792c3da1, the same bug exists
for the READ phase as well.

This would manifest first as a lost SCSI response, and eventual
hung task during fabric driver logout or re-login, as existing
shutdown logic waited for the COMPARE_AND_WRITE se_cmd->cmd_kref
to reach zero.

To address this bug, compare_and_write_callback() has been changed
to set post_ret = 1 and return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE
as necessary to signal failure status.

Reported-by: Bill Borsari <wgb@xxxxxxxxx>
Cc: Bill Borsari <wgb@xxxxxxxxx>
Tested-by: Gary Guo <ghg@xxxxxxxxx>
Cc: Gary Guo <ghg@xxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/target/target_core_sbc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -506,8 +506,11 @@ static sense_reason_t compare_and_write_
* been failed with a non-zero SCSI status.
if (cmd->scsi_status) {
- pr_err("compare_and_write_callback: non zero scsi_status:"
+ pr_debug("compare_and_write_callback: non zero scsi_status:"
" 0x%02x\n", cmd->scsi_status);
+ *post_ret = 1;
+ if (cmd->scsi_status == SAM_STAT_CHECK_CONDITION)
goto out;