return to;
}
+/*
+ * autoremove_wake_function, but remove even on failure to wake up, because we
+ * know that default_wake_function/ttwu will only fail if the thread is already
+ * woken, and in that case the ep_poll loop will remove the entry anyways, not
+ * try to reuse it.
+ */
+static int ep_autoremove_wake_function(struct wait_queue_entry *wq_entry,
+ unsigned int mode, int sync, void *key)
+{
+ int ret = default_wake_function(wq_entry, mode, sync, key);
+
+ list_del_init(&wq_entry->entry);
+ return ret;
+}
+
/**
* ep_poll - Retrieves ready events, and delivers them to the caller-supplied
* event buffer.
* normal wakeup path no need to call __remove_wait_queue()
* explicitly, thus ep->lock is not taken, which halts the
* event delivery.
+ *
+ * In fact, we now use an even more aggressive function that
+ * unconditionally removes, because we don't reuse the wait
+ * entry between loop iterations. This lets us also avoid the
+ * performance issue if a process is killed, causing all of its
+ * threads to wake up without being removed normally.
*/
init_wait(&wait);
+ wait.func = ep_autoremove_wake_function;
write_lock_irq(&ep->lock);
/*