2021-01-19 23:11:49

by Adrian Hunter

Subject: [PATCH 1/4] scsi: ufs: Add exception event tracepoint

Currently, exception event status can be read from wExceptionEventStatus
attribute (sysfs file attributes/exception_event_status under the UFS host
controller device directory). Polling that attribute to track UFS exception
events is impractical, so add a tracepoint to track exception events for
testing and debugging purposes.

Note, by the time the exception event status is read, the exception event
may have cleared, so the value can be zero - see example below.

Note also, only enabled exception events can be reported. A subsequent
patch adds the ability for users to enable selected exception events via
debugfs.

Example with driver instrumented to enable all exception events:

# echo 1 > /sys/kernel/debug/tracing/events/ufs/ufshcd_exception_event/enable

... do some I/O ...

# cat /sys/kernel/debug/tracing/trace
# tracer: nop
#
# entries-in-buffer/entries-written: 3/3 #P:5
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
kworker/2:2-173 [002] .... 731.486419: ufshcd_exception_event: 0000:00:12.5: exception event status 0x0
kworker/2:2-173 [002] .... 732.608918: ufshcd_exception_event: 0000:00:12.5: exception event status 0x4
kworker/2:2-173 [002] .... 732.609312: ufshcd_exception_event: 0000:00:12.5: exception event status 0x4

Signed-off-by: Adrian Hunter <[email protected]>
---
drivers/scsi/ufs/ufshcd.c | 2 ++
include/trace/events/ufs.h | 21 +++++++++++++++++++++
2 files changed, 23 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 46a499b7e8a8..7d46b2c278dd 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5624,6 +5624,8 @@ static void ufshcd_exception_event_handler(struct work_struct *work)
goto out;
}

+ trace_ufshcd_exception_event(dev_name(hba->dev), status);
+
status &= hba->ee_ctrl_mask;

if (status & MASK_EE_URGENT_BKOPS)
diff --git a/include/trace/events/ufs.h b/include/trace/events/ufs.h
index e151477d645c..5a2586217eb6 100644
--- a/include/trace/events/ufs.h
+++ b/include/trace/events/ufs.h
@@ -349,6 +349,27 @@ TRACE_EVENT(ufshcd_upiu,
)
);

+TRACE_EVENT(ufshcd_exception_event,
+
+ TP_PROTO(const char *dev_name, u16 status),
+
+ TP_ARGS(dev_name, status),
+
+ TP_STRUCT__entry(
+ __string(dev_name, dev_name)
+ __field(u16, status)
+ ),
+
+ TP_fast_assign(
+ __assign_str(dev_name, dev_name);
+ __entry->status = status;
+ ),
+
+ TP_printk("%s: exception event status 0x%x",
+ __get_str(dev_name), __entry->status
+ )
+);
+
#endif /* if !defined(_TRACE_UFS_H) || defined(TRACE_HEADER_MULTI_READ) */

/* This part must be outside protection */
--
2.17.1

2021-02-03 08:39:39

by Bean Huo

Subject: Re: [PATCH 1/4] scsi: ufs: Add exception event tracepoint

On Tue, 2021-01-19 at 16:15 +0200, Adrian Hunter wrote:
> Currently, exception event status can be read from
> wExceptionEventStatus
> attribute (sysfs file attributes/exception_event_status under the UFS
> host
> controller device directory). Polling that attribute to track UFS
> exception
> events is impractical, so add a tracepoint to track exception events
> for
> testing and debugging purposes.
>
> Note, by the time the exception event status is read, the exception
> event
> may have cleared, so the value can be zero - see example below.
>
> Note also, only enabled exception events can be reported. A
> subsequent
> patch adds the ability for users to enable selected exception events
> via
> debugfs.
>
> Example with driver instrumented to enable all exception events:
>
> # echo 1 >
> /sys/kernel/debug/tracing/events/ufs/ufshcd_exception_event/enable
>
> ... do some I/O ...
>
> # cat /sys/kernel/debug/tracing/trace
> # tracer: nop
> #
> # entries-in-buffer/entries-written: 3/3 #P:5
> #
> # _-----=> irqs-off
> # / _----=> need-resched
> # | / _---=> hardirq/softirq
> # || / _--=> preempt-depth
> # ||| / delay
> # TASK-PID CPU# |||| TIMESTAMP FUNCTION
> # | | | |||| | |
> kworker/2:2-173 [002] .... 731.486419:
> ufshcd_exception_event: 0000:00:12.5: exception event status 0x0
> kworker/2:2-173 [002] .... 732.608918:
> ufshcd_exception_event: 0000:00:12.5: exception event status 0x4
> kworker/2:2-173 [002] .... 732.609312:
> ufshcd_exception_event: 0000:00:12.5: exception event status 0x4

Hi Adrian

aAbove print has two trace strings "exception event" in each event
print, it is somehow redundant to me, why not replace the second one
with the event string name?


ufshcd_exception_event: 0000:00:12.5: LOW_TEMP 0x4

or just status:

ufshcd_exception_event: 0000:00:12.5: status 0x4


Bean

>

>