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perf_events: Fix races and clean up perf_event and perf_mmap_data interaction

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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>
This commit is contained in:
Peter Zijlstra
2010-05-27 12:54:41 +02:00
committed by Ingo Molnar
parent 67a3e12b05
commit ac9721f3f5
2 changed files with 129 additions and 100 deletions
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5
include/linux/perf_event.h
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@@ -585,6 +585,7 @@ enum perf_event_active_state {
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 @@ struct perf_mmap_data {
#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 @@ struct perf_event {
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 @@ struct perf_event {
/* 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 */