[PATCH 4.9 29/86] perf tools: Fix trigger class trigger_on()

Greg Kroah-Hartman
2018-03-16T15:31:05Z

From: Adrian Hunter <adrian.hunter@intel.com>

commit de19e5c3c51fdb1ff20d0f61d099db902ff7494b upstream.

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@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
tools/perf/util/trigger.h | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

--- a/tools/perf/util/trigger.h
+++ b/tools/perf/util/trigger.h
@@ -11,7 +11,7 @@
* States and transits:
*
*
- * OFF--(on)--> READY --(hit)--> HIT
+ * OFF--> ON --> READY --(hit)--> HIT
* ^ |
* | (ready)
* | |
@@ -26,8 +26,9 @@ 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;
};
@@ -49,7 +50,7 @@ static inline bool trigger_is_error(stru
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)