commit 97eaf5300b9d0cd99c310bf8c4a0f2f3296d88a3
author Frederic Weisbecker <fweisbec@gmail.com> Sun Oct 18 15:33:50 2009 +0200
committer Frederic Weisbecker <fweisbec@gmail.com> Tue Nov 03 19:11:53 2009 +0100
tree aa047f4c078e2c9aeabcbcc9e33d93a50366b8e9
parent 41a48d14f6991020c9bb6b93e289ca5b411ed09a

perf/core: Add a callback to perf events

A simple callback in a perf event can be used for multiple purposes.
For example it is useful for triggered based events like hardware
breakpoints that need a callback to dispatch a triggered breakpoint
event.

v2: Simplify a bit the callback attribution as suggested by Paul
    Mackerras

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mundt <lethal@linux-sh.org>

kernel/perf_event.c

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 02d4ff0..5087125 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4293,6 +4293,7 @@
 		   struct perf_event_context *ctx,
 		   struct perf_event *group_leader,
 		   struct perf_event *parent_event,
+		   perf_callback_t callback,
 		   gfp_t gfpflags)
 {
 	const struct pmu *pmu;
@@ -4335,6 +4336,11 @@
 
 	event->state		= PERF_EVENT_STATE_INACTIVE;
 
+	if (!callback && parent_event)
+		callback = parent_event->callback;
+	
+	event->callback	= callback;
+
 	if (attr->disabled)
 		event->state = PERF_EVENT_STATE_OFF;
 
@@ -4611,7 +4617,7 @@
 	}
 
 	event = perf_event_alloc(&attr, cpu, ctx, group_leader,
-				     NULL, GFP_KERNEL);
+				     NULL, NULL, GFP_KERNEL);
 	err = PTR_ERR(event);
 	if (IS_ERR(event))
 		goto err_put_context;
@@ -4668,7 +4674,7 @@
  */
 struct perf_event *
 perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
-				 pid_t pid)
+				 pid_t pid, perf_callback_t callback)
 {
 	struct perf_event *event;
 	struct perf_event_context *ctx;
@@ -4683,7 +4689,7 @@
 		return NULL ;
 
 	event = perf_event_alloc(attr, cpu, ctx, NULL,
-				     NULL, GFP_KERNEL);
+				     NULL, callback, GFP_KERNEL);
 	err = PTR_ERR(event);
 	if (IS_ERR(event))
 		goto err_put_context;
@@ -4736,7 +4742,7 @@
 	child_event = perf_event_alloc(&parent_event->attr,
 					   parent_event->cpu, child_ctx,
 					   group_leader, parent_event,
-					   GFP_KERNEL);
+					   NULL, GFP_KERNEL);
 	if (IS_ERR(child_event))
 		return child_event;
 	get_ctx(child_ctx);