perf_events: Undo some recursion damage

Make perf_swevent_get_recursion_context return a context number
and disable preemption.

This could be used to remove the IRQ disable from the trace bit
and index the per-cpu buffer with.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091123103819.993226816@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 13 insertions, 12 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 74e98b1d3391..43adbd7f0010 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -874,8 +874,8 @@ extern int perf_output_begin(struct perf_output_handle *handle,
 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);
+extern int perf_swevent_get_recursion_context(void);
+extern void perf_swevent_put_recursion_context(int rctx);
 #else
 static inline void
 perf_event_task_sched_in(struct task_struct *task, int cpu)             { }
@@ -904,8 +904,8 @@ static inline void perf_event_mmap(struct vm_area_struct *vma)		{ }
 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)          { }
+static inline int  perf_swevent_get_recursion_context(void)  { return -1; }
+static inline void perf_swevent_put_recursion_context(int rctx)         { }
 
 #endif
 
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index c222ef5238bf..c3417c13e3ed 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -724,8 +724,8 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
 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); \
+        extern int perf_swevent_get_recursion_context(void);            \
+        extern void perf_swevent_put_recursion_context(int rctx);       \
         struct ftrace_event_call *event_call = &event_##call;           \
         extern void perf_tp_event(int, u64, u64, void *, int);          \
         struct ftrace_raw_##call *entry;                                \
@@ -736,8 +736,8 @@ static void ftrace_profile_##call(proto)				\
         int __data_size;                                                \
         char *trace_buf;                                                \
         char *raw_data;                                                 \
-        int *recursion;                                                 \
         int __cpu;                                                      \
+        int rctx;                                                       \
         int pc;                                                         \
                                                                         \
         pc = preempt_count();                                           \
@@ -753,8 +753,9 @@ static void ftrace_profile_##call(proto)				\
                                                                         \
         local_irq_save(irq_flags);                                      \
                                                                         \
-        if (perf_swevent_get_recursion_context(&recursion))             \
-                goto end_recursion;                                             \
+        rctx = perf_swevent_get_recursion_context();                    \
+        if (rctx < 0)                                                   \
+                goto end_recursion;                                     \
                                                                         \
         __cpu = smp_processor_id();                                     \
                                                                         \
@@ -781,9 +782,9 @@ static void ftrace_profile_##call(proto)				\
         perf_tp_event(event_call->id, __addr, __count, entry,           \
                              __entry_size);                             \
                                                                         \
-end:                                                            \
-        perf_swevent_put_recursion_context(recursion);                  \
-end_recursion:                                                                  \
+end:                                                                    \
+        perf_swevent_put_recursion_context(rctx);                       \
+end_recursion:                                                          \
         local_irq_restore(irq_flags);                                   \
                                                                         \
 }