net: introduce new macro net_get_random_once

[~andy/linux] / net / core / utils.c

diff --git a/net/core/utils.c b/net/core/utils.c
index aa88e23fc87aa44f95f8794cf234846d8d06d21d..bf09371e19b146369a6c580e52700588440adf49 100644 (file)
--- a/net/core/utils.c
+++ b/net/core/utils.c
@@ -338,3 +338,51 @@ void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
                                  csum_unfold(*sum)));
 }
 EXPORT_SYMBOL(inet_proto_csum_replace16);
+
+struct __net_random_once_work {
+       struct work_struct work;
+       struct static_key *key;
+};
+
+static void __net_random_once_deferred(struct work_struct *w)
+{
+       struct __net_random_once_work *work =
+               container_of(w, struct __net_random_once_work, work);
+       if (!static_key_enabled(work->key))
+               static_key_slow_inc(work->key);
+       kfree(work);
+}
+
+static void __net_random_once_disable_jump(struct static_key *key)
+{
+       struct __net_random_once_work *w;
+
+       w = kmalloc(sizeof(*w), GFP_ATOMIC);
+       if (!w)
+               return;
+
+       INIT_WORK(&w->work, __net_random_once_deferred);
+       w->key = key;
+       schedule_work(&w->work);
+}
+
+bool __net_get_random_once(void *buf, int nbytes, bool *done,
+                          struct static_key *done_key)
+{
+       static DEFINE_SPINLOCK(lock);
+
+       spin_lock_bh(&lock);
+       if (*done) {
+               spin_unlock_bh(&lock);
+               return false;
+       }
+
+       get_random_bytes(buf, nbytes);
+       *done = true;
+       spin_unlock_bh(&lock);
+
+       __net_random_once_disable_jump(done_key);
+
+       return true;
+}
+EXPORT_SYMBOL(__net_get_random_once);