Patch "target: Fix ordered task CHECK_CONDITION early exception handling" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

target: Fix ordered task CHECK_CONDITION early exception handling

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
target-fix-ordered-task-check_condition-early-exception-handling.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Nicholas Bellinger <[email protected]>
Date: Mon, 13 Jun 2016 22:58:09 -0700
Subject: target: Fix ordered task CHECK_CONDITION early exception handling

From: Nicholas Bellinger <[email protected]>

commit 410c29dfbfdf73d0d0b5d14a21868ab038eca703 upstream.

If a Simple command is sent with a failure, target_setup_cmd_from_cdb returns with TCM_UNSUPPORTED_SCSI_OPCODE or TCM_INVALID_CDB_FIELD.

So in the cases where target_setup_cmd_from_cdb returns an error, we never get far enough to call target_execute_cmd to increment simple_cmds. Since simple_cmds isn't incremented, the result of the failure from target_setup_cmd_from_cdb causes transport_generic_request_failure to decrement simple_cmds, due to call to transport_complete_task_attr.

With this dev->simple_cmds or dev->dev_ordered_sync is now -1, not 0. So when a subsequent command with an Ordered Task is sent, it causes a hang, since dev->simple_cmds is at -1.

---
 drivers/target/target_core_transport.c |    7 ++++++-
 include/target/target_core_base.h      |    1 +
 2 files changed, 7 insertions(+), 1 deletion(-)

@@ -1815,6 +1815,8 @@ static bool target_handle_task_attr(stru
 	if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH)
 		return false;
 
+	cmd->se_cmd_flags |= SCF_TASK_ATTR_SET;
+
 	/*
 	 * Check for the existence of HEAD_OF_QUEUE, and if true return 1
 	 * to allow the passed struct se_cmd list of tasks to the front of the list.

@@ -1937,6 +1939,9 @@ static void transport_complete_task_attr
 	if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH)
 		return;
 
+	if (!(cmd->se_cmd_flags & SCF_TASK_ATTR_SET))
+		goto restart;
+
 	if (cmd->sam_task_attr == TCM_SIMPLE_TAG) {
 		atomic_dec_mb(&dev->simple_cmds);
 		dev->dev_cur_ordered_id++;

@@ -1953,7 +1958,7 @@ static void transport_complete_task_attr
 		pr_debug("Incremented dev_cur_ordered_id: %u for ORDERED\n",
 			 dev->dev_cur_ordered_id);
 	}
-
+restart:
 	target_restart_delayed_cmds(dev);
 }
 

@@ -139,6 +139,7 @@ enum se_cmd_flags_table {
 	SCF_COMPARE_AND_WRITE_POST	= 0x00100000,
 	SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC = 0x00200000,
 	SCF_ACK_KREF			= 0x00400000,
+	SCF_TASK_ATTR_SET		= 0x01000000,
 };
 
 /* struct se_dev_entry->lun_flags and struct se_lun->lun_access */

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/target-fix-max_unmap_lba_count-calc-overflow.patch queue-4.4/target-fix-ordered-task-check_condition-early-exception-handling.patch queue-4.4/target-fix-race-between-iscsi-target-connection-shutdown-abort_task.patch queue-4.4/target-fix-ordered-task-target_setup_cmd_from_cdb-exception-hang.patch queue-4.4/iscsi-target-fix-panic-when-adding-second-tcp-connection-to-iscsi-session.patch queue-4.4/target-fix-missing-complete-during-abort_task-cmd_t_fabric_stop.patch