perf_events: Fix FORK events

Commit 22e1908 ("Honour event state for aux stream data")
introduced a bug where we would drop FORK events.

The thing is that we deliver FORK events to the child process'
event, which at that time will be PERF_EVENT_STATE_INACTIVE
because the child won't be scheduled in (we're in the middle of
fork).

Solve this twice, change the event state filter to exclude only
disabled (STATE_OFF) or worse, and deliver FORK events to the
current (parent).

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Anton Blanchard <anton@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
LKML-Reference: <1266142324.5273.411.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/perf_event.c

@@ -3259,16 +3259,14 @@ static void perf_event_task_output(struct perf_event *event,
 	task_event->event_id.tid = perf_event_tid(event, task);
 	task_event->event_id.ptid = perf_event_tid(event, current);
 
-	task_event->event_id.time = perf_clock();
-
 	perf_output_put(&handle, task_event->event_id);
 
 	perf_output_end(&handle);
 }
 
 static int perf_event_task_match(struct perf_event *event)
 {
-	if (event->state != PERF_EVENT_STATE_ACTIVE)
+	if (event->state < PERF_EVENT_STATE_INACTIVE)
 		return 0;
 
 	if (event->cpu != -1 && event->cpu != smp_processor_id())
@@ -3300,7 +3298,7 @@ static void perf_event_task_event(struct perf_task_event *task_event)
 	cpuctx = &get_cpu_var(perf_cpu_context);
 	perf_event_task_ctx(&cpuctx->ctx, task_event);
 	if (!ctx)
-		ctx = rcu_dereference(task_event->task->perf_event_ctxp);
+		ctx = rcu_dereference(current->perf_event_ctxp);
 	if (ctx)
 		perf_event_task_ctx(ctx, task_event);
 	put_cpu_var(perf_cpu_context);
@@ -3331,6 +3329,7 @@ static void perf_event_task(struct task_struct *task,
 			/* .ppid */
 			/* .tid  */
 			/* .ptid */
+			.time = perf_clock(),
 		},
 	};
 
@@ -3380,7 +3379,7 @@ static void perf_event_comm_output(struct perf_event *event,
 
 static int perf_event_comm_match(struct perf_event *event)
 {
-	if (event->state != PERF_EVENT_STATE_ACTIVE)
+	if (event->state < PERF_EVENT_STATE_INACTIVE)
 		return 0;
 
 	if (event->cpu != -1 && event->cpu != smp_processor_id())
@@ -3500,7 +3499,7 @@ static void perf_event_mmap_output(struct perf_event *event,
 static int perf_event_mmap_match(struct perf_event *event,
 				   struct perf_mmap_event *mmap_event)
 {
-	if (event->state != PERF_EVENT_STATE_ACTIVE)
+	if (event->state < PERF_EVENT_STATE_INACTIVE)
 		return 0;
 
 	if (event->cpu != -1 && event->cpu != smp_processor_id())