net: move net_get_random_once to lib

[linux-2.6-microblaze.git] / lib / once.c

diff --git a/lib/once.c b/lib/once.c
new file mode 100644 (file)
index 0000000..2d5a7de
--- /dev/null
+++ b/lib/once.c
@@ -0,0 +1,54 @@
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/once.h>
+#include <linux/random.h>
+
+struct __random_once_work {
+       struct work_struct work;
+       struct static_key *key;
+};
+
+static void __random_once_deferred(struct work_struct *w)
+{
+       struct __random_once_work *work;
+
+       work = container_of(w, struct __random_once_work, work);
+       BUG_ON(!static_key_enabled(work->key));
+       static_key_slow_dec(work->key);
+       kfree(work);
+}
+
+static void __random_once_disable_jump(struct static_key *key)
+{
+       struct __random_once_work *w;
+
+       w = kmalloc(sizeof(*w), GFP_ATOMIC);
+       if (!w)
+               return;
+
+       INIT_WORK(&w->work, __random_once_deferred);
+       w->key = key;
+       schedule_work(&w->work);
+}
+
+bool __get_random_once(void *buf, int nbytes, bool *done,
+                      struct static_key *once_key)
+{
+       static DEFINE_SPINLOCK(lock);
+       unsigned long flags;
+
+       spin_lock_irqsave(&lock, flags);
+       if (*done) {
+               spin_unlock_irqrestore(&lock, flags);
+               return false;
+       }
+
+       get_random_bytes(buf, nbytes);
+       *done = true;
+       spin_unlock_irqrestore(&lock, flags);
+
+       __random_once_disable_jump(once_key);
+
+       return true;
+}
+EXPORT_SYMBOL(__get_random_once);