Two fixes for the tracing system.
o When trace_printk() is used with a non constant format descriptor,
it adds a NULL pointer into the trace format section, and the code
isn't prepared to deal with it. This bug appeared by a change that
was added in v3.5.
o The ftracetest (selftests section) can't handle testing histograms
when histograms are not configured. Currently it shows that they
fail the test, when they should state that they are unsupported.
This bug was added in the 4.7 merge window with the addition of
the historgram code.
ftracetest: Fix hist unsupported result in hist selftests
When histograms are not configured in the kernel, the ftracetest histogram
selftests should return "unsupported" and not "Failed". To detect this, the
test scripts have:
FEATURE=`grep hist events/sched/sched_process_fork/trigger`
if [ -z "$FEATURE" ]; then
echo "hist trigger is not supported"
exit_unsupported
fi
The problem is that '-e' is in effect and any error will cause the program
to terminate. The grep for 'hist' fails, because it is not compiled it (thus
unsupported), but because grep has an error code for failing to find the
string, it causes the program to terminate, and is marked as a failed test.
Namhyung Kim recommended to test for the "hist" file located in
events/sched/sched_process_fork/hist instead, as it is more inline with the
other checks. As the hist file is only created if the histogram feature is
enabled, that is a valid check.
Link: http://lkml.kernel.org/r/20160523151538.4ea9ce0c@gandalf.local.home
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 76929ab51f0ee ("kselftests/ftrace: Add hist trigger testcases")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
3 files changed
