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    Subject[PATCH v2 6/9] perf,tracing: Prepare the perf-trace interface for RCU changes
    The tracepoint interface will stop providing regular RCU context; make
    sure we do it ourselves, since perf makes use of regular RCU protected
    data.

    Suggested-by: Steven Rostedt (VMware) <rosted@goodmis.org>
    Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    ---
    kernel/events/core.c | 5 +++++
    1 file changed, 5 insertions(+)

    --- a/kernel/events/core.c
    +++ b/kernel/events/core.c
    @@ -8950,6 +8950,7 @@ void perf_tp_event(u16 event_type, u64 c
    {
    struct perf_sample_data data;
    struct perf_event *event;
    + unsigned long rcu_flags;

    struct perf_raw_record raw = {
    .frag = {
    @@ -8961,6 +8962,8 @@ void perf_tp_event(u16 event_type, u64 c
    perf_sample_data_init(&data, 0, 0);
    data.raw = &raw;

    + rcu_flags = trace_rcu_enter();
    +
    perf_trace_buf_update(record, event_type);

    hlist_for_each_entry_rcu(event, head, hlist_entry) {
    @@ -8996,6 +8999,8 @@ void perf_tp_event(u16 event_type, u64 c
    }

    perf_swevent_put_recursion_context(rctx);
    +
    + trace_rcu_exit(rcu_flags);
    }
    EXPORT_SYMBOL_GPL(perf_tp_event);


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