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Subject[PATCH 4.14 116/193] target: Fix caw_sem leak in transport_generic_request_failure
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

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

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

commit fd2f928b0ddd2fe8876d4f1344df2ace2b715a4d upstream.

With the recent addition of transport_check_aborted_status() within
transport_generic_request_failure() to avoid sending a SCSI status
exception after CMD_T_ABORTED w/ TAS=1 has occured, it introduced
a COMPARE_AND_WRITE early failure regression.

Namely when COMPARE_AND_WRITE fails and se_device->caw_sem has
been taken by sbc_compare_and_write(), if the new check for
transport_check_aborted_status() returns true and exits,
cmd->transport_complete_callback() -> compare_and_write_post()
is skipped never releasing se_device->caw_sem.

This regression was originally introduced by:

commit e3b88ee95b4e4bf3e9729a4695d695b9c7c296c8
Author: Bart Van Assche <bart.vanassche@sandisk.com>
Date: Tue Feb 14 16:25:45 2017 -0800

target: Fix handling of aborted failed commands

To address this bug, move the transport_check_aborted_status()
call after transport_complete_task_attr() and
cmd->transport_complete_callback().

Cc: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/target/target_core_transport.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1730,9 +1730,6 @@ void transport_generic_request_failure(s
{
int ret = 0, post_ret = 0;

- if (transport_check_aborted_status(cmd, 1))
- return;
-
pr_debug("-----[ Storage Engine Exception; sense_reason %d\n",
sense_reason);
target_show_cmd("-----[ ", cmd);
@@ -1741,6 +1738,7 @@ void transport_generic_request_failure(s
* For SAM Task Attribute emulation for failed struct se_cmd
*/
transport_complete_task_attr(cmd);
+
/*
* Handle special case for COMPARE_AND_WRITE failure, where the
* callback is expected to drop the per device ->caw_sem.
@@ -1749,6 +1747,9 @@ void transport_generic_request_failure(s
cmd->transport_complete_callback)
cmd->transport_complete_callback(cmd, false, &post_ret);

+ if (transport_check_aborted_status(cmd, 1))
+ return;
+
switch (sense_reason) {
case TCM_NON_EXISTENT_LUN:
case TCM_UNSUPPORTED_SCSI_OPCODE:

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