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>
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 43360c1..47bbdf9 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -137,13 +137,8 @@
#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 */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 36fe89f..74e98b1 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -874,6 +874,8 @@
extern void perf_output_end(struct perf_output_handle *handle);
extern void perf_output_copy(struct perf_output_handle *handle,
const void *buf, unsigned int len);
+extern int perf_swevent_get_recursion_context(int **recursion);
+extern void perf_swevent_put_recursion_context(int *recursion);
#else
static inline void
perf_event_task_sched_in(struct task_struct *task, int cpu) { }
@@ -902,6 +904,8 @@
static inline void perf_event_comm(struct task_struct *tsk) { }
static inline void perf_event_fork(struct task_struct *tsk) { }
static inline void perf_event_init(void) { }
+static int perf_swevent_get_recursion_context(int **recursion) { return -1; }
+static void perf_swevent_put_recursion_context(int *recursion) { }
#endif
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 4945d1c..c222ef5 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -724,16 +724,19 @@
static void ftrace_profile_##call(proto) \
{ \
struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
+ extern int perf_swevent_get_recursion_context(int **recursion); \
+ extern void perf_swevent_put_recursion_context(int *recursion); \
struct ftrace_event_call *event_call = &event_##call; \
extern void perf_tp_event(int, u64, u64, void *, int); \
struct ftrace_raw_##call *entry; \
- struct perf_trace_buf *trace_buf; \
u64 __addr = 0, __count = 1; \
unsigned long irq_flags; \
struct trace_entry *ent; \
int __entry_size; \
int __data_size; \
+ char *trace_buf; \
char *raw_data; \
+ int *recursion; \
int __cpu; \
int pc; \
\
@@ -749,6 +752,10 @@
return; \
\
local_irq_save(irq_flags); \
+ \
+ if (perf_swevent_get_recursion_context(&recursion)) \
+ goto end_recursion; \
+ \
__cpu = smp_processor_id(); \
\
if (in_nmi()) \
@@ -759,13 +766,7 @@
if (!trace_buf) \
goto end; \
\
- trace_buf = per_cpu_ptr(trace_buf, __cpu); \
- if (trace_buf->recursion++) \
- goto end_recursion; \
- \
- barrier(); \
- \
- raw_data = trace_buf->buf; \
+ raw_data = per_cpu_ptr(trace_buf, __cpu); \
\
*(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; \
entry = (struct ftrace_raw_##call *)raw_data; \
@@ -780,9 +781,9 @@
perf_tp_event(event_call->id, __addr, __count, entry, \
__entry_size); \
\
-end_recursion: \
- trace_buf->recursion--; \
-end: \
+end: \
+ perf_swevent_put_recursion_context(recursion); \
+end_recursion: \
local_irq_restore(irq_flags); \
\
}