tracing: Use the perf recursion protection from trace event

When we commit a trace to perf, we first check if we are
recursing in the same buffer so that we don't mess-up the buffer
with a recursing trace. But later on, we do the same check from
perf to avoid commit recursion. The recursion check is desired
early before we touch the buffer but we want to do this check
only once.

Then export the recursion protection from perf and use it from
the trace events before submitting a trace.

v2: Put appropriate Reported-by tag

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
LKML-Reference: <1258864015-10579-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 7 deletions

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 43360c1d8f70..47bbdf9c38d0 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -137,13 +137,8 @@ struct ftrace_event_call {
 
 #define FTRACE_MAX_PROFILE_SIZE 2048
 
-struct perf_trace_buf {
-        char    buf[FTRACE_MAX_PROFILE_SIZE];
-        int     recursion;
-};
-
-extern struct perf_trace_buf    *perf_trace_buf;
-extern struct perf_trace_buf    *perf_trace_buf_nmi;
+extern char *perf_trace_buf;
+extern char *perf_trace_buf_nmi;
 
 #define MAX_FILTER_PRED         32
 #define MAX_FILTER_STR_VAL      256     /* Should handle KSYM_SYMBOL_LEN */