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Commit dff0ca9e authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

target: Fix ordered task target_setup_cmd_from_cdb exception hang 



If a command with a Simple task attribute is failed due to a Unit
Attention, then a subsequent command with an Ordered task attribute
will hang forever.  The reason for this is that the Unit Attention
status is checked for in target_setup_cmd_from_cdb, before the call
to target_execute_cmd, which calls target_handle_task_attr, which
in turn increments dev->simple_cmds.

However, transport_generic_request_failure still calls
transport_complete_task_attr, which will decrement dev->simple_cmds.
In this case, simple_cmds is now -1.  So when a command with the
Ordered task attribute is sent, target_handle_task_attr sees that
dev->simple_cmds is not 0, so it decides it can't execute the
command until all the (nonexistent) Simple commands have completed.

Reported-by: default avatarMichael Cyr <mikecyr@linux.vnet.ibm.com>
Tested-by: default avatarMichael Cyr <mikecyr@linux.vnet.ibm.com>
Reported-by: default avatarBryant G. Ly <bryantly@linux.vnet.ibm.com>
Tested-by: default avatarBryant G. Ly <bryantly@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # 4.4+
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent ea263c7f

drivers/target/target_core_internal.h

+1 −0
Original line number Diff line number Diff line
@@ -146,6 +146,7 @@ sense_reason_t target_cmd_size_check(struct se_cmd *cmd, unsigned int size); 
void	target_qf_do_work(struct work_struct *work);

bool	target_check_wce(struct se_device *dev);

bool	target_check_fua(struct se_device *dev);

void	__target_execute_cmd(struct se_cmd *, bool);



/* target_core_stat.c */

void	target_stat_setup_dev_default_groups(struct se_device *);

drivers/target/target_core_sbc.c

+1 −1
Original line number Diff line number Diff line
@@ -602,7 +602,7 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool succes 
	cmd->transport_state |= CMD_T_ACTIVE|CMD_T_BUSY|CMD_T_SENT;

	spin_unlock_irq(&cmd->t_state_lock);



	__target_execute_cmd(cmd);

	__target_execute_cmd(cmd, false);



	kfree(buf);

	return ret;

drivers/target/target_core_transport.c

+35 −27
Original line number Diff line number Diff line
@@ -1303,23 +1303,6 @@ target_setup_cmd_from_cdb(struct se_cmd *cmd, unsigned char *cdb) 


	trace_target_sequencer_start(cmd);



	/*

	 * Check for an existing UNIT ATTENTION condition

	 */

	ret = target_scsi3_ua_check(cmd);

	if (ret)

		return ret;



	ret = target_alua_state_check(cmd);

	if (ret)

		return ret;



	ret = target_check_reservation(cmd);

	if (ret) {

		cmd->scsi_status = SAM_STAT_RESERVATION_CONFLICT;

		return ret;

	}



	ret = dev->transport->parse_cdb(cmd);

	if (ret == TCM_UNSUPPORTED_SCSI_OPCODE)

		pr_warn_ratelimited("%s/%s: Unsupported SCSI Opcode 0x%02x, sending CHECK_CONDITION.\n",
@@ -1761,21 +1744,46 @@ void transport_generic_request_failure(struct se_cmd *cmd, 
}

EXPORT_SYMBOL(transport_generic_request_failure);



void __target_execute_cmd(struct se_cmd *cmd)

void __target_execute_cmd(struct se_cmd *cmd, bool do_checks)

{

	sense_reason_t ret;



	if (cmd->execute_cmd) {

		ret = cmd->execute_cmd(cmd);

	if (!cmd->execute_cmd) {

		ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

		goto err;

	}

	if (do_checks) {

		/*

		 * Check for an existing UNIT ATTENTION condition after

		 * target_handle_task_attr() has done SAM task attr

		 * checking, and possibly have already defered execution

		 * out to target_restart_delayed_cmds() context.

		 */

		ret = target_scsi3_ua_check(cmd);

		if (ret)

			goto err;



		ret = target_alua_state_check(cmd);

		if (ret)

			goto err;



		ret = target_check_reservation(cmd);

		if (ret) {

			cmd->scsi_status = SAM_STAT_RESERVATION_CONFLICT;

			goto err;

		}

	}



	ret = cmd->execute_cmd(cmd);

	if (!ret)

		return;

err:

	spin_lock_irq(&cmd->t_state_lock);

	cmd->transport_state &= ~(CMD_T_BUSY|CMD_T_SENT);

	spin_unlock_irq(&cmd->t_state_lock);



	transport_generic_request_failure(cmd, ret);

}

	}

}



static int target_write_prot_action(struct se_cmd *cmd)

{
@@ -1899,7 +1907,7 @@ void target_execute_cmd(struct se_cmd *cmd) 
		return;

	}



	__target_execute_cmd(cmd);

	__target_execute_cmd(cmd, true);

}

EXPORT_SYMBOL(target_execute_cmd);
@@ -1923,7 +1931,7 @@ static void target_restart_delayed_cmds(struct se_device *dev) 
		list_del(&cmd->se_delayed_node);

		spin_unlock(&dev->delayed_cmd_lock);



		__target_execute_cmd(cmd);

		__target_execute_cmd(cmd, true);



		if (cmd->sam_task_attr == TCM_ORDERED_TAG)

			break;

include/target/target_core_fabric.h

+0 −1
Original line number Diff line number Diff line
@@ -163,7 +163,6 @@ int core_tmr_alloc_req(struct se_cmd *, void *, u8, gfp_t); 
void	core_tmr_release_req(struct se_tmr_req *);

int	transport_generic_handle_tmr(struct se_cmd *);

void	transport_generic_request_failure(struct se_cmd *, sense_reason_t);

void	__target_execute_cmd(struct se_cmd *);

int	transport_lookup_tmr_lun(struct se_cmd *, u64);

void	core_allocate_nexus_loss_ua(struct se_node_acl *acl);