diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 7ab4ad00f..f294f2761 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6387,6 +6387,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, if (!group_leader) group_leader = event; + mutex_init(&event->group_leader_mutex); mutex_init(&event->child_mutex); INIT_LIST_HEAD(&event->child_list); @@ -6767,6 +6768,16 @@ SYSCALL_DEFINE5(perf_event_open, group_leader = NULL; } + /* + * Take the group_leader's group_leader_mutex before observing + * anything in the group leader that leads to changes in ctx, + * many of which may be changing on another thread. + * In particular, we want to take this lock before deciding + * whether we need to move_group. + */ + if (group_leader) + mutex_lock(&group_leader->group_leader_mutex); + if (pid != -1 && !(flags & PERF_FLAG_PID_CGROUP)) { task = find_lively_task_by_vpid(pid); if (IS_ERR(task)) { @@ -6935,6 +6946,8 @@ SYSCALL_DEFINE5(perf_event_open, ++ctx->generation; perf_unpin_context(ctx); mutex_unlock(&ctx->mutex); + if (group_leader) + mutex_unlock(&group_leader->group_leader_mutex); put_online_cpus(); @@ -6970,6 +6983,8 @@ err_task: if (task) put_task_struct(task); err_group_fd: + if (group_leader) + mutex_unlock(&group_leader->group_leader_mutex); fdput(group); err_fd: put_unused_fd(event_fd); |