[PATCH] target: Unsupported SCSI Opcode Fix

[PATCH] target: Unsupported SCSI Opcode Fix

[Bryant G. Ly]

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.

Signed-off-by: Michael Cyr <mikecyr@linux.vnet.ibm.com>
Signed-off-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
---
 drivers/target/target_core_transport.c | 6 ++++++
 include/target/target_core_base.h      | 3 ++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 0a8f0a6..a2e447a 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1824,6 +1824,8 @@ static bool target_handle_task_attr(struct se_cmd *cmd)
 	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.
@@ -1946,6 +1948,9 @@ static void transport_complete_task_attr(struct se_cmd *cmd)
 	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++;
@@ -1963,6 +1968,7 @@ static void transport_complete_task_attr(struct se_cmd *cmd)
 			 dev->dev_cur_ordered_id);
 	}
 
+restart:
 	target_restart_delayed_cmds(dev);
 }
 
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index e5d0948..276f5a5 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -139,7 +139,8 @@ enum se_cmd_flags_table {
 	SCF_COMPARE_AND_WRITE_POST	= 0x00100000,
 	SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC = 0x00200000,
 	SCF_ACK_KREF			= 0x00400000,
-	SCF_USE_CPUID			= 0x00800000,
+	SCF_USE_CPUID                   = 0x00800000,
+	SCF_TASK_ATTR_SET               = 0x01000000,
 };
 
 /* struct se_dev_entry->lun_flags and struct se_lun->lun_access */
-- 
2.5.4 (Apple Git-61)

Re: [PATCH] target: Unsupported SCSI Opcode Fix

[Nicholas A. Bellinger]

On Thu, 2016-06-30 at 13:50 -0500, Bryant G. Ly wrote:
> 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.
> 
> Signed-off-by: Michael Cyr <mikecyr@linux.vnet.ibm.com>
> Signed-off-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
> ---
>  drivers/target/target_core_transport.c | 6 ++++++
>  include/target/target_core_base.h      | 3 ++-
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 

Applied to target-pending/for-next, preceeding the ibmvscsis commit.

Thanks again Bryant + Michael for reviewing + testing this patch.