perf/bpf: Convert perf_event_array to use struct file

Robustify refcounting.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160126045947.GA40151@ast-mbp.thefacebook.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 10 insertions, 4 deletions

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 45dd798bcd37..326a75e884db 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -191,14 +191,17 @@ static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
         struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
         struct bpf_array *array = container_of(map, struct bpf_array, map);
         struct perf_event *event;
+        struct file *file;
 
         if (unlikely(index >= array->map.max_entries))
                 return -E2BIG;
 
-        event = (struct perf_event *)array->ptrs[index];
-        if (!event)
+        file = (struct file *)array->ptrs[index];
+        if (unlikely(!file))
                 return -ENOENT;
 
+        event = file->private_data;
+
         /* make sure event is local and doesn't have pmu::count */
         if (event->oncpu != smp_processor_id() ||
             event->pmu->count)
@@ -228,6 +231,7 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
         void *data = (void *) (long) r4;
         struct perf_sample_data sample_data;
         struct perf_event *event;
+        struct file *file;
         struct perf_raw_record raw = {
                 .size = size,
                 .data = data,
@@ -236,10 +240,12 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
         if (unlikely(index >= array->map.max_entries))
                 return -E2BIG;
 
-        event = (struct perf_event *)array->ptrs[index];
-        if (unlikely(!event))
+        file = (struct file *)array->ptrs[index];
+        if (unlikely(!file))
                 return -ENOENT;
 
+        event = file->private_data;
+
         if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
                      event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
                 return -EINVAL;