{
struct perf_event_context *ctx;
- rcu_read_lock();
retry:
+ /*
+ * One of the few rules of preemptible RCU is that one cannot do
+ * rcu_read_unlock() while holding a scheduler (or nested) lock when
+ * part of the read side critical section was preemptible -- see
+ * rcu_read_unlock_special().
+ *
+ * Since ctx->lock nests under rq->lock we must ensure the entire read
+ * side critical section is non-preemptible.
+ */
+ preempt_disable();
+ rcu_read_lock();
ctx = rcu_dereference(task->perf_event_ctxp[ctxn]);
if (ctx) {
/*
raw_spin_lock_irqsave(&ctx->lock, *flags);
if (ctx != rcu_dereference(task->perf_event_ctxp[ctxn])) {
raw_spin_unlock_irqrestore(&ctx->lock, *flags);
+ rcu_read_unlock();
+ preempt_enable();
goto retry;
}
}
}
rcu_read_unlock();
+ preempt_enable();
return ctx;
}
struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
int err;
- if (WARN_ON_ONCE(!ctx->is_active))
+ /*
+ * There's a time window between 'ctx->is_active' check
+ * in perf_event_enable function and this place having:
+ * - IRQs on
+ * - ctx->lock unlocked
+ *
+ * where the task could be killed and 'ctx' deactivated
+ * by perf_event_exit_task.
+ */
+ if (!ctx->is_active)
return -EINVAL;
raw_spin_lock(&ctx->lock);
return count;
}
-#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
-
static struct device_attribute pmu_dev_attrs[] = {
__ATTR_RO(type),
__ATTR_RW(perf_event_mux_interval_ms),
* child.
*/
- child_ctx = alloc_perf_context(event->pmu, child);
+ child_ctx = alloc_perf_context(parent_ctx->pmu, child);
if (!child_ctx)
return -ENOMEM;
}
}
-static void __cpuinit perf_event_init_cpu(int cpu)
+static void perf_event_init_cpu(int cpu)
{
struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
.priority = INT_MIN,
};
-static int __cpuinit
+static int
perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
{
unsigned int cpu = (long)hcpu;