perf_events: Fix races and clean up perf_event and perf_mmap_data interaction
In order to move toward separate buffer objects, rework the whole
perf_mmap_data construct to be a more self-sufficient entity, one
with its own lifetime rules.
This greatly sanitizes the whole output redirection code, which
was riddled with bugs and races.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index fb6c91e..4906985 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -585,6 +585,7 @@
struct file;
struct perf_mmap_data {
+ atomic_t refcount;
struct rcu_head rcu_head;
#ifdef CONFIG_PERF_USE_VMALLOC
struct work_struct work;
@@ -592,7 +593,6 @@
#endif
int nr_pages; /* nr of data pages */
int writable; /* are we writable */
- int nr_locked; /* nr pages mlocked */
atomic_t poll; /* POLL_ for wakeups */
@@ -643,7 +643,6 @@
int nr_siblings;
int group_flags;
struct perf_event *group_leader;
- struct perf_event *output;
const struct pmu *pmu;
enum perf_event_active_state state;
@@ -704,6 +703,8 @@
/* mmap bits */
struct mutex mmap_mutex;
atomic_t mmap_count;
+ int mmap_locked;
+ struct user_struct *mmap_user;
struct perf_mmap_data *data;
/* poll related */