On Wed, Feb 28, 2018 at 10:39:04AM +0200, Adrian Hunter wrote:
> trigger_on() means that the trigger is available but not ready, however
> trigger_on() was making it ready. That can segfault if the signal comes
> before trigger_ready(). e.g. (USR2 signal delivery not shown)
>
> $ perf record -e intel_pt//u -S sleep 1
> perf: Segmentation fault
> Obtained 16 stack frames.
> /home/ahunter/bin/perf(sighandler_dump_stack+0x40) [0x4ec550]
> /lib/x86_64-linux-gnu/libc.so.6(+0x36caf) [0x7fa76411acaf]
> /home/ahunter/bin/perf(perf_evsel__disable+0x26) [0x4b9dd6]
> /home/ahunter/bin/perf() [0x43a45b]
> /lib/x86_64-linux-gnu/libc.so.6(+0x36caf) [0x7fa76411acaf]
> /lib/x86_64-linux-gnu/libc.so.6(__xstat64+0x15) [0x7fa7641d2cc5]
> /home/ahunter/bin/perf() [0x4ec6c9]
> /home/ahunter/bin/perf() [0x4ec73b]
> /home/ahunter/bin/perf() [0x4ec73b]
> /home/ahunter/bin/perf() [0x4ec73b]
> /home/ahunter/bin/perf() [0x4eca15]
> /home/ahunter/bin/perf(machine__create_kernel_maps+0x257) [0x4f0b77]
> /home/ahunter/bin/perf(perf_session__new+0xc0) [0x4f86f0]
> /home/ahunter/bin/perf(cmd_record+0x722) [0x43c132]
> /home/ahunter/bin/perf() [0x4a11ae]
> /home/ahunter/bin/perf(main+0x5d4) [0x427fb4]
>
> Note, for testing purposes, this is hard to hit unless you add some sleep()
> in builtin-record.c before record__open().
>
> Fixes: 3dcc4436fa6f ("perf tools: Introduce trigger class")
> Cc: <[email protected]>
> Signed-off-by: Adrian Hunter <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
thanks,
jirka
> ---
> tools/perf/util/trigger.h | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/util/trigger.h b/tools/perf/util/trigger.h
> index 370138e7e35c..88223bc7c82b 100644
> --- a/tools/perf/util/trigger.h
> +++ b/tools/perf/util/trigger.h
> @@ -12,7 +12,7 @@
> * States and transits:
> *
> *
> - * OFF--(on)--> READY --(hit)--> HIT
> + * OFF--> ON --> READY --(hit)--> HIT
> * ^ |
> * | (ready)
> * | |
> @@ -27,8 +27,9 @@ struct trigger {
> volatile enum {
> TRIGGER_ERROR = -2,
> TRIGGER_OFF = -1,
> - TRIGGER_READY = 0,
> - TRIGGER_HIT = 1,
> + TRIGGER_ON = 0,
> + TRIGGER_READY = 1,
> + TRIGGER_HIT = 2,
> } state;
> const char *name;
> };
> @@ -50,7 +51,7 @@ static inline bool trigger_is_error(struct trigger *t)
> static inline void trigger_on(struct trigger *t)
> {
> TRIGGER_WARN_ONCE(t, TRIGGER_OFF);
> - t->state = TRIGGER_READY;
> + t->state = TRIGGER_ON;
> }
>
> static inline void trigger_ready(struct trigger *t)
> --
> 1.9.1
>
