linux-kernel - [PATCH 4.4 02/56] target: Fix compare_and_write

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Message-Id: <20170518104840.499422984@linuxfoundation.org>
Date:   Thu, 18 May 2017 12:48:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Bill Borsari <wgb@...era.io>,
        Gary Guo <ghg@...era.io>,
        Nicholas Bellinger <nab@...ux-iscsi.org>
Subject: [PATCH 4.4 02/56] target: Fix compare_and_write_callback handling for non GOOD status

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

------------------

From: Nicholas Bellinger <nab@...ux-iscsi.org>

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@...era.io>
Cc: Bill Borsari <wgb@...era.io>
Tested-by: Gary Guo <ghg@...era.io>
Cc: Gary Guo <ghg@...era.io>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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
@@ -498,8 +498,11 @@ 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)
+			ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 		goto out;
 	}