target: Add counters for ABORT_TASK success + failure

Nicholas Bellinger · Nicholas Bellinger · commit c87ba9c49c1f · 2017-02-26T16:21:06.000-08:00
This patch introduces two counters for ABORT_TASK success +
failure under:

   /sys/kernel/config/target/core/$HBA/$DEV/statistics/scsi_tgt_dev/

that are useful for diagnosing various backend device latency
and front fabric issues.

Normally when folks see alot of aborts_complete happening,
it means the backend device I/O completion latency is high,
and not returning completions fast enough before host side
timeouts trigger.

And normally when folks see alot of aborts_no_task, it means
completions are being posted by target-core into fabric driver
code, but the responses aren't making it back to the host.

Signed-off-by: Nicholas Bellinger &lt;nab@linux-iscsi.org&gt;
diff --git a/drivers/target/target_core_stat.c b/drivers/target/target_core_stat.c
@@ -158,12 +158,28 @@ static ssize_t target_stat_tgt_resets_show(struct config_item *item,
 			atomic_long_read(&to_stat_tgt_dev(item)->num_resets));
 }
 
+static ssize_t target_stat_tgt_aborts_complete_show(struct config_item *item,
+		char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%lu\n",
+			atomic_long_read(&to_stat_tgt_dev(item)->aborts_complete));
+}
+
+static ssize_t target_stat_tgt_aborts_no_task_show(struct config_item *item,
+		char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%lu\n",
+			atomic_long_read(&to_stat_tgt_dev(item)->aborts_no_task));
+}
+
 CONFIGFS_ATTR_RO(target_stat_tgt_, inst);
 CONFIGFS_ATTR_RO(target_stat_tgt_, indx);
 CONFIGFS_ATTR_RO(target_stat_tgt_, num_lus);
 CONFIGFS_ATTR_RO(target_stat_tgt_, status);
 CONFIGFS_ATTR_RO(target_stat_tgt_, non_access_lus);
 CONFIGFS_ATTR_RO(target_stat_tgt_, resets);
+CONFIGFS_ATTR_RO(target_stat_tgt_, aborts_complete);
+CONFIGFS_ATTR_RO(target_stat_tgt_, aborts_no_task);
 
 static struct configfs_attribute *target_stat_scsi_tgt_dev_attrs[] = {
 	&target_stat_tgt_attr_inst,
@@ -172,6 +188,8 @@ static struct configfs_attribute *target_stat_scsi_tgt_dev_attrs[] = {
 	&target_stat_tgt_attr_status,
 	&target_stat_tgt_attr_non_access_lus,
 	&target_stat_tgt_attr_resets,
+	&target_stat_tgt_attr_aborts_complete,
+	&target_stat_tgt_attr_aborts_no_task,
 	NULL,
 };
 
diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
@@ -190,13 +190,15 @@ void core_tmr_abort_task(
 		printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for"
 				" ref_tag: %llu\n", ref_tag);
 		tmr->response = TMR_FUNCTION_COMPLETE;
+		atomic_long_inc(&dev->aborts_complete);
 		return;
 	}
 	spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
 
 	printk("ABORT_TASK: Sending TMR_TASK_DOES_NOT_EXIST for ref_tag: %lld\n",
 			tmr->ref_task_tag);
 	tmr->response = TMR_TASK_DOES_NOT_EXIST;
+	atomic_long_inc(&dev->aborts_no_task);
 }
 
 static void core_tmr_drain_tmr_list(
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
@@ -766,6 +766,8 @@ struct se_device {
 	u32			dev_index;
 	u64			creation_time;
 	atomic_long_t		num_resets;
+	atomic_long_t		aborts_complete;
+	atomic_long_t		aborts_no_task;
 	atomic_long_t		num_cmds;
 	atomic_long_t		read_bytes;
 	atomic_long_t		write_bytes;

Original file line number	Diff line number	Diff line change
`@@ -190,13 +190,15 @@ void core_tmr_abort_task(`
`190`	`190`	`printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for"`
`191`	`191`	`" ref_tag: %llu\n", ref_tag);`
`192`	`192`	`tmr->response = TMR_FUNCTION_COMPLETE;`
	`193`	`+ atomic_long_inc(&dev->aborts_complete);`
`193`	`194`	`return;`
`194`	`195`	`}`
`195`	`196`	`spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);`
`196`	`197`
`197`	`198`	`printk("ABORT_TASK: Sending TMR_TASK_DOES_NOT_EXIST for ref_tag: %lld\n",`
`198`	`199`	`tmr->ref_task_tag);`
`199`	`200`	`tmr->response = TMR_TASK_DOES_NOT_EXIST;`
	`201`	`+ atomic_long_inc(&dev->aborts_no_task);`
`200`	`202`	`}`
`201`	`203`
`202`	`204`	`static void core_tmr_drain_tmr_list(`