From: Steven Rostedt Date: Wed, 16 May 2018 09:36:44 -0400 Subject: [PATCH 2/5] tracing: Add field parsing hist error for hist triggers Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.16/older/patches-4.16.8-rt3.tar.xz From: Tom Zanussi [ commit 5ec432d7bf9dd3b4a2b84f8974e3adb71f45fb1d ] If the user specifies a nonexistent field for a hist trigger, the current code correctly flags that as an error, but doesn't tell the user what happened. Fix this by invoking hist_err() with an appropriate message when nonexistent fields are specified. Before: # echo 'hist:keys=pid:ts0=common_timestamp.usecs' >> /sys/kernel/debug/tracing/events/sched/sched_switch/trigger -su: echo: write error: Invalid argument # cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist After: # echo 'hist:keys=pid:ts0=common_timestamp.usecs' >> /sys/kernel/debug/tracing/events/sched/sched_switch/trigger -su: echo: write error: Invalid argument # cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist ERROR: Couldn't find field: pid Last command: keys=pid:ts0=common_timestamp.usecs Link: http://lkml.kernel.org/r/fdc8746969d16906120f162b99dd71c741e0b62c.1524790601.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi Reported-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sebastian Andrzej Siewior --- kernel/trace/trace_events_hist.c | 1 + 1 file changed, 1 insertion(+) --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -2482,6 +2482,7 @@ parse_field(struct hist_trigger_data *hi else { field = trace_find_event_field(file->event_call, field_name); if (!field || !field->size) { + hist_err("Couldn't find field: ", field_name); field = ERR_PTR(-EINVAL); goto out; }