Re: [PATCH] Fix for hang of Ordered task in TCM

From: Bryant G Ly
Date: Mon May 23 2016 - 19:17:46 EST



Quoting "Nicholas A. Bellinger" <nab@xxxxxxxxxxxxxxx>:

<SNIP>

So AFAICT for delayed commands, the above patch ends up skipping these
three checks subsequently when doing __target_execute_cmd() directly
from target_restart_delayed_cmds(), no..?

After pondering this some more, what about moving these checks into
__target_execute_cmd() to handle both target_core_transport.c cases
instead..?

We'll also need a parameter for internal COMPARE_AND_WRITE usage
within compare_and_write_callback(), to bypass checks upon secondary
->execute_cmd() WRITE payload submission after READ + COMPARE has
completed successfully.

WDYT..?

diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h
index fc91e85..e2c970a 100644
--- a/drivers/target/target_core_internal.h
+++ b/drivers/target/target_core_internal.h
@@ -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 *);
diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index a9057aa..04f616b 100644
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -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;
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 6c089af..f3e93dd 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1761,20 +1761,45 @@ 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 +1924,7 @@ 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 +1948,7 @@ 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;
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index ec79da3..334f107 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -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);


Looks good to me. Nick just to let you know I've been working with Mike on VSCSI
Target Fabric and we need this patch in kernel 4.4 do you know of the process in
getting that there?

Thanks

-Bryant

--
1.9.1

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