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Once total_ref_count is negative, the next call to perf_trace_event_reg will register perf_probe but will not allocate perf_trace_buf and sets it to NULL instead. The subsequent trace_##call() will mem abort in perf_trace_buf_alloc because memset will be called on the NULL perf_trace_buf. Gracefully handle the error in perf_trace_event_unreg to prevent double unregister. Signed-off-by: Aditya Chillara --- kernel/trace/trace_event_perf.c | 8 ++++++-- kernel/trace/trace_events.c | 3 +-- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_per= f.c index 61e3a2620fa3c9417ac23cf5a18aeb86e7393dcc..247db88accd88eb0acf3692ea59= 3d576519ce8b1 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -154,12 +154,16 @@ static int perf_trace_event_reg(struct trace_event_ca= ll *tp_event, static void perf_trace_event_unreg(struct perf_event *p_event) { struct trace_event_call *tp_event =3D p_event->tp_event; - int i; + int i, ret; =20 if (--tp_event->perf_refcount > 0) return; =20 - tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); + ret =3D tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); + if (ret) { + ++tp_event->perf_refcount; + return; + } =20 /* * Ensure our callback won't be called anymore. The buffers diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 0356cae0cf74e79075f607bc841df05568688baa..50e0e08b29aa6617a04b191419a= d1e587adf69fe 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -530,10 +530,9 @@ int trace_event_reg(struct trace_event_call *call, call->class->perf_probe, call); case TRACE_REG_PERF_UNREGISTER: - tracepoint_probe_unregister(call->tp, + return tracepoint_probe_unregister(call->tp, call->class->perf_probe, call); - return 0; case TRACE_REG_PERF_OPEN: case TRACE_REG_PERF_CLOSE: case TRACE_REG_PERF_ADD: --=20 2.34.1