diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2013-06-17 19:02:04 +0200 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2013-07-18 21:31:27 -0400 |
| commit | b8ebfd3f7113b63dda93d76bfec638c00e6bd514 (patch) | |
| tree | 5a72a20c5fa86fe1c284308111132345f249c671 /kernel | |
| parent | d611851b421731e2afd9cb956daae001af57a423 (diff) | |
| download | lwn-b8ebfd3f7113b63dda93d76bfec638c00e6bd514.tar.gz lwn-b8ebfd3f7113b63dda93d76bfec638c00e6bd514.zip | |
tracing/function: Avoid perf_trace_buf_*() if event_function.perf_events is empty
perf_trace_buf_prepare() + perf_trace_buf_submit(head, task => NULL)
make no sense if hlist_empty(head). Change perf_ftrace_function_call()
to check event_function.perf_events beforehand.
Link: http://lkml.kernel.org/r/20130617170204.GA19803@redhat.com
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_event_perf.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index 84b1e045faba..12df5573086e 100644 --- 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, ®s, head, NULL); |