[PATCH 1/3] perf: Do not allow to create kernel events without handler

[Jiri Olsa <jolsa@kernel.org>]

Force kernel events to specify the handler, because
there's no use for kernel perf event without it.

Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/events/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1cf24b3e42ec..75c4ff8d1590 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7355,6 +7355,9 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
 	struct perf_event *event;
 	int err;
 
+	if (WARN_ON(!overflow_handler))
+		return NULL;
+
 	/*
 	 * Get the target context (task or percpu):
 	 */
-- 
1.8.3.1