Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6

[pandora-kernel.git] / kernel / perf_event.c

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 67d9bd7..126a302 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2201,13 +2201,6 @@ find_lively_task_by_vpid(pid_t vpid)
        if (!task)
                return ERR_PTR(-ESRCH);
 
-       /*
-        * Can't attach events to a dying task.
-        */
-       err = -ESRCH;
-       if (task->flags & PF_EXITING)
-               goto errout;
-
        /* Reuse ptrace permission checks for now. */
        err = -EACCES;
        if (!ptrace_may_access(task, PTRACE_MODE_READ))
@@ -2268,14 +2261,27 @@ retry:
 
                get_ctx(ctx);
 
-               if (cmpxchg(&task->perf_event_ctxp[ctxn], NULL, ctx)) {
-                       /*
-                        * We raced with some other task; use
-                        * the context they set.
-                        */
+               err = 0;
+               mutex_lock(&task->perf_event_mutex);
+               /*
+                * If it has already passed perf_event_exit_task().
+                * we must see PF_EXITING, it takes this mutex too.
+                */
+               if (task->flags & PF_EXITING)
+                       err = -ESRCH;
+               else if (task->perf_event_ctxp[ctxn])
+                       err = -EAGAIN;
+               else
+                       rcu_assign_pointer(task->perf_event_ctxp[ctxn], ctx);
+               mutex_unlock(&task->perf_event_mutex);
+
+               if (unlikely(err)) {
                        put_task_struct(task);
                        kfree(ctx);
-                       goto retry;
+
+                       if (err == -EAGAIN)
+                               goto retry;
+                       goto errout;
                }
        }
 
@@ -4661,7 +4667,7 @@ int perf_swevent_get_recursion_context(void)
 }
 EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
 
-void inline perf_swevent_put_recursion_context(int rctx)
+inline void perf_swevent_put_recursion_context(int rctx)
 {
        struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
 
@@ -5374,6 +5380,8 @@ free_dev:
        goto out;
 }
 
+static struct lock_class_key cpuctx_mutex;
+
 int perf_pmu_register(struct pmu *pmu, char *name, int type)
 {
        int cpu, ret;
@@ -5422,6 +5430,7 @@ skip_type:
 
                cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
                __perf_event_init_context(&cpuctx->ctx);
+               lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
                cpuctx->ctx.type = cpu_context;
                cpuctx->ctx.pmu = pmu;
                cpuctx->jiffies_interval = 1;
@@ -6127,7 +6136,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
         * scheduled, so we are now safe from rescheduling changing
         * our context.
         */
-       child_ctx = child->perf_event_ctxp[ctxn];
+       child_ctx = rcu_dereference_raw(child->perf_event_ctxp[ctxn]);
        task_ctx_sched_out(child_ctx, EVENT_ALL);
 
        /*
@@ -6440,11 +6449,6 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
        unsigned long flags;
        int ret = 0;
 
-       child->perf_event_ctxp[ctxn] = NULL;
-
-       mutex_init(&child->perf_event_mutex);
-       INIT_LIST_HEAD(&child->perf_event_list);
-
        if (likely(!parent->perf_event_ctxp[ctxn]))
                return 0;
 
@@ -6533,6 +6537,10 @@ int perf_event_init_task(struct task_struct *child)
 {
        int ctxn, ret;
 
+       memset(child->perf_event_ctxp, 0, sizeof(child->perf_event_ctxp));
+       mutex_init(&child->perf_event_mutex);
+       INIT_LIST_HEAD(&child->perf_event_list);
+
        for_each_task_context_nr(ctxn) {
                ret = perf_event_init_context(child, ctxn);
                if (ret)