Commit f404da6e authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (VMware)

tracing: Add 'last error' error facility for hist triggers

With the addition of variables and actions, it's become necessary to
provide more detailed error information to users about syntax errors.

Add a 'last error' facility accessible via the erroring event's 'hist'
file.  Reading the hist file after an error will display more detailed
information about what went wrong, if information is available.  This
extended error information will be available until the next hist
trigger command for that event.

  # echo xxx > /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger
  echo: write error: Invalid argument

  # cat /sys/kernel/debug/tracing/events/sched/sched_wakeup/hist

  ERROR: Couldn't yyy: zzz
  Last command: xxx

Also add specific error messages for variable and action errors.

Link: http://lkml.kernel.org/r/64e9c422fc8aeafcc2f7a3b4328c0cffe7969129.1516069914.git.tom.zanussi@linux.intel.comSigned-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 7e8b88a3
...@@ -188,6 +188,26 @@ ...@@ -188,6 +188,26 @@
interpreted as microseconds. interpreted as microseconds.
cpu int - the cpu on which the event occurred. cpu int - the cpu on which the event occurred.
Extended error information
--------------------------
For some error conditions encountered when invoking a hist trigger
command, extended error information is available via the
corresponding event's 'hist' file. Reading the hist file after an
error will display more detailed information about what went wrong,
if information is available. This extended error information will
be available until the next hist trigger command for that event.
If available for a given error condition, the extended error
information and usage takes the following form:
# echo xxx > /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger
echo: write error: Invalid argument
# cat /sys/kernel/debug/tracing/events/sched/sched_wakeup/hist
ERROR: Couldn't yyy: zzz
Last command: xxx
6.2 'hist' trigger examples 6.2 'hist' trigger examples
--------------------------- ---------------------------
......
This diff is collapsed.
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment