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>
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 81de28dc..ba8e0f4 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5745,7 +5745,8 @@
struct task_struct *task,
struct perf_event *group_leader,
struct perf_event *parent_event,
- perf_overflow_handler_t overflow_handler)
+ perf_overflow_handler_t overflow_handler,
+ void *context)
{
struct pmu *pmu;
struct perf_event *event;
@@ -5803,10 +5804,13 @@
#endif
}
- if (!overflow_handler && parent_event)
+ if (!overflow_handler && parent_event) {
overflow_handler = parent_event->overflow_handler;
+ context = parent_event->overflow_handler_context;
+ }
event->overflow_handler = overflow_handler;
+ event->overflow_handler_context = context;
if (attr->disabled)
event->state = PERF_EVENT_STATE_OFF;
@@ -6073,7 +6077,8 @@
}
}
- event = perf_event_alloc(&attr, cpu, task, group_leader, NULL, NULL);
+ event = perf_event_alloc(&attr, cpu, task, group_leader, NULL,
+ NULL, NULL);
if (IS_ERR(event)) {
err = PTR_ERR(event);
goto err_task;
@@ -6258,7 +6263,8 @@
struct perf_event *
perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
struct task_struct *task,
- perf_overflow_handler_t overflow_handler)
+ perf_overflow_handler_t overflow_handler,
+ void *context)
{
struct perf_event_context *ctx;
struct perf_event *event;
@@ -6268,7 +6274,8 @@
* Get the target context (task or percpu):
*/
- event = perf_event_alloc(attr, cpu, task, NULL, NULL, overflow_handler);
+ event = perf_event_alloc(attr, cpu, task, NULL, NULL,
+ overflow_handler, context);
if (IS_ERR(event)) {
err = PTR_ERR(event);
goto err;
@@ -6552,7 +6559,7 @@
parent_event->cpu,
child,
group_leader, parent_event,
- NULL);
+ NULL, NULL);
if (IS_ERR(child_event))
return child_event;
get_ctx(child_ctx);
@@ -6579,6 +6586,8 @@
child_event->ctx = child_ctx;
child_event->overflow_handler = parent_event->overflow_handler;
+ child_event->overflow_handler_context
+ = parent_event->overflow_handler_context;
/*
* Precalculate sample_data sizes