From: Robert Richter robert.richter@linaro.org
Implement try_get_event() as counter part to put_event(). Put both in internal.h to make it available to other perf files.
Signed-off-by: Robert Richter robert.richter@linaro.org Signed-off-by: Robert Richter rric@kernel.org --- kernel/events/core.c | 9 +++------ kernel/events/internal.h | 12 ++++++++++++ 2 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 5dcc5fe..c9a5d4c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3242,13 +3242,10 @@ EXPORT_SYMBOL_GPL(perf_event_release_kernel); /* * Called when the last reference to the file is gone. */ -static void put_event(struct perf_event *event) +void __put_event(struct perf_event *event) { struct task_struct *owner;
- if (!atomic_long_dec_and_test(&event->refcount)) - return; - rcu_read_lock(); owner = ACCESS_ONCE(event->owner); /* @@ -3781,7 +3778,7 @@ static void ring_buffer_detach_all(struct ring_buffer *rb) again: rcu_read_lock(); list_for_each_entry_rcu(event, &rb->event_list, rb_entry) { - if (!atomic_long_inc_not_zero(&event->refcount)) { + if (!try_get_event(event)) { /* * This event is en-route to free_event() which will * detach it and remove it from the list. @@ -7445,7 +7442,7 @@ inherit_event(struct perf_event *parent_event, if (IS_ERR(child_event)) return child_event;
- if (!atomic_long_inc_not_zero(&parent_event->refcount)) { + if (!try_get_event(parent_event)) { free_event(child_event); return NULL; } diff --git a/kernel/events/internal.h b/kernel/events/internal.h index ca65997..96a07d2 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -178,4 +178,16 @@ static inline bool arch_perf_have_user_stack_dump(void) #define perf_user_stack_pointer(regs) 0 #endif /* CONFIG_HAVE_PERF_USER_STACK_DUMP */
+static inline bool try_get_event(struct perf_event *event) +{ + return atomic_long_inc_not_zero(&event->refcount) != 0; +} +extern void __put_event(struct perf_event *event); +static inline void put_event(struct perf_event *event) +{ + if (!atomic_long_dec_and_test(&event->refcount)) + return; + __put_event(event); +} + #endif /* _KERNEL_EVENTS_INTERNAL_H */