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authorOleg Nesterov <oleg@redhat.com>2013-06-17 19:02:04 +0200
committerSteven Rostedt <rostedt@goodmis.org>2013-07-18 21:31:27 -0400
commitb8ebfd3f7113b63dda93d76bfec638c00e6bd514 (patch)
tree5a72a20c5fa86fe1c284308111132345f249c671 /kernel
parentd611851b421731e2afd9cb956daae001af57a423 (diff)
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.c6
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, &regs, head, NULL);