From: Adrian Hunter adrian.hunter@intel.com
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().
Signed-off-by: Adrian Hunter adrian.hunter@intel.com Acked-by: Jiri Olsa jolsa@kernel.org Cc: Wang Nan wangnan0@huawei.com Cc: stable@vger.kernel.org Fixes: 3dcc4436fa6f ("perf tools: Introduce trigger class") Link: http://lkml.kernel.org/r/1519807144-30694-1-git-send-email-adrian.hunter@int... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com --- 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)