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target: Fix ordered task target_setup_cmd_from_cdb exception hang

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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: Michael Cyr <mikecyr@linux.vnet.ibm.com>
Tested-by: Michael Cyr <mikecyr@linux.vnet.ibm.com>
Reported-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Tested-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # 4.4+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Nicholas Bellinger 2016-05-17 22:19:10 -07:00
parent ea263c7fad
commit dff0ca9ea7
4 changed files with 37 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/target/target_core_internal.h
View File

@ -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 *);

2
drivers/target/target_core_sbc.c
View File

@ -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;

62
drivers/target/target_core_transport.c
View File

@ -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",
@ -1761,20 +1744,45 @@ queue_full:
}
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 (ret) {
spin_lock_irq(&cmd->t_state_lock);
cmd->transport_state &= ~(CMD_T_BUSY|CMD_T_SENT);
spin_unlock_irq(&cmd->t_state_lock);
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;
transport_generic_request_failure(cmd, ret);
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;

1
include/target/target_core_fabric.h
View File

@ -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);