tracing/function: Avoid perf_trace_buf_*() if event_function.perf_events is empty

[linux-imx.git] / kernel / trace / trace_event_perf.c

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 84b1e045faba836583fb371d285f49e79bfa6bd0..12df5573086e147283b9375c87e0ffaeb3a3bd45 100644 (file)
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -266,6 +266,10 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
        struct pt_regs regs;
        int rctx;
 
+       head = this_cpu_ptr(event_function.perf_events);
+       if (hlist_empty(head))
+               return;
+
 #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
                    sizeof(u64)) - sizeof(u32))
 
@@ -279,8 +283,6 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
 
        entry->ip = ip;
        entry->parent_ip = parent_ip;
-
-       head = this_cpu_ptr(event_function.perf_events);
        perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
                              1, &regs, head, NULL);