diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-11 10:20:06 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-11 10:20:06 -0800 |
| commit | d5b76bef01047843cc65bd018046c76182b1fc81 (patch) | |
| tree | 13aa1b0019d2afeb53257edde54e36c3fa86ecdf /kernel | |
| parent | 4e4f74a7eebbc52eaa1dc3c0be6b3c68c0875b09 (diff) | |
| parent | 451d24d1e5f40bad000fa9abe36ddb16fc9928cb (diff) | |
Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
"A kernel crash fix plus three tooling fixes"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Fix crash in perf_event_read()
perf callchain: Reference count maps
perf diff: Fix -o/--order option behavior (again)
perf diff: Fix segfault on 'perf diff -o N' option
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index e5aaa806702d..e235bb991bdd 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3487,14 +3487,15 @@ struct perf_read_data { int ret; }; -static int find_cpu_to_read(struct perf_event *event, int local_cpu) +static int __perf_event_read_cpu(struct perf_event *event, int event_cpu) { - int event_cpu = event->oncpu; u16 local_pkg, event_pkg; if (event->group_caps & PERF_EV_CAP_READ_ACTIVE_PKG) { - event_pkg = topology_physical_package_id(event_cpu); - local_pkg = topology_physical_package_id(local_cpu); + int local_cpu = smp_processor_id(); + + event_pkg = topology_physical_package_id(event_cpu); + local_pkg = topology_physical_package_id(local_cpu); if (event_pkg == local_pkg) return local_cpu; @@ -3624,7 +3625,7 @@ u64 perf_event_read_local(struct perf_event *event) static int perf_event_read(struct perf_event *event, bool group) { - int ret = 0, cpu_to_read, local_cpu; + int event_cpu, ret = 0; /* * If event is enabled and currently active on a CPU, update the @@ -3637,21 +3638,25 @@ static int perf_event_read(struct perf_event *event, bool group) .ret = 0, }; - local_cpu = get_cpu(); - cpu_to_read = find_cpu_to_read(event, local_cpu); - put_cpu(); + event_cpu = READ_ONCE(event->oncpu); + if ((unsigned)event_cpu >= nr_cpu_ids) + return 0; + + preempt_disable(); + event_cpu = __perf_event_read_cpu(event, event_cpu); /* * Purposely ignore the smp_call_function_single() return * value. * - * If event->oncpu isn't a valid CPU it means the event got + * If event_cpu isn't a valid CPU it means the event got * scheduled out and that will have updated the event count. * * Therefore, either way, we'll have an up-to-date event count * after this. */ - (void)smp_call_function_single(cpu_to_read, __perf_event_read, &data, 1); + (void)smp_call_function_single(event_cpu, __perf_event_read, &data, 1); + preempt_enable(); ret = data.ret; } else if (event->state == PERF_EVENT_STATE_INACTIVE) { struct perf_event_context *ctx = event->ctx; |