perf: Add context field to perf_event

The perf_event overflow handler does not receive any caller-derived
argument, so many callers need to resort to looking up the perf_event
in their local data structure.  This is ugly and doesn't scale if a
single callback services many perf_events.

Fix by adding a context parameter to perf_event_create_kernel_counter()
(and derived hardware breakpoints APIs) and storing it in the perf_event.
The field can be accessed from the callback as event->overflow_handler_context.
All callers are updated.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1309362157-6596-2-git-send-email-avi@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index a5f54b973bdb..2a08cacb1628 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -839,6 +839,7 @@ struct perf_event {
         u64                             id;
 
         perf_overflow_handler_t         overflow_handler;
+        void                            *overflow_handler_context;
 
 #ifdef CONFIG_EVENT_TRACING
         struct ftrace_event_call        *tp_event;
@@ -960,7 +961,8 @@ extern struct perf_event *
 perf_event_create_kernel_counter(struct perf_event_attr *attr,
                                 int cpu,
                                 struct task_struct *task,
-                                perf_overflow_handler_t callback);
+                                perf_overflow_handler_t callback,
+                                void *context);
 extern u64 perf_event_read_value(struct perf_event *event,
                                  u64 *enabled, u64 *running);