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>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index fa151d4..8d54e6d 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -544,6 +544,8 @@ struct perf_pending_entry {
        void (*func)(struct perf_pending_entry *);
 };
 
+typedef void (*perf_callback_t)(struct perf_event *, void *);
+
 /**
  * struct perf_event - performance event kernel representation:
  */
@@ -639,6 +641,8 @@ struct perf_event {
        struct event_filter             *filter;
 #endif
 
+       perf_callback_t                 callback;
+
 #endif /* CONFIG_PERF_EVENTS */
 };
 
@@ -748,7 +752,8 @@ extern int perf_event_release_kernel(struct perf_event *event);
 extern 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);
 extern u64 perf_event_read_value(struct perf_event *event);
 
 struct perf_sample_data {

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 02d4ff0..5087125 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4293,6 +4293,7 @@ perf_event_alloc(struct perf_event_attr *attr,
                   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 @@ perf_event_alloc(struct perf_event_attr *attr,
 
        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 @@ SYSCALL_DEFINE5(perf_event_open,
        }
 
        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 @@ err_put_context:
  */
 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 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
                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 @@ inherit_event(struct perf_event *parent_event,
        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);