[PATCH v2 6/9] perf,tracing: Prepare the perf-trace interface for RCU changes

Peter Zijlstra
2020-02-12T21:01:45Z

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);