summaryrefslogtreecommitdiff
path: root/lib/once.c
diff options
context:
space:
mode:
authorHannes Frederic Sowa <hannes@stressinduktion.org>2015-10-08 02:20:35 +0300
committerDavid S. Miller <davem@davemloft.net>2015-10-08 15:26:35 +0300
commit46234253b9363894a254844a6550b4cc5f3edfe8 (patch)
treeab3b795f7ff1765d2f7dbb318b5fae08945a0bdf /lib/once.c
parent28335a7445202a3d118145a07d9138e9881ebe18 (diff)
downloadlinux-46234253b9363894a254844a6550b4cc5f3edfe8.tar.xz
net: move net_get_random_once to lib
There's no good reason why users outside of networking should not be using this facility, f.e. for initializing their seeds. Therefore, make it accessible from there as get_random_once(). Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib/once.c')
-rw-r--r--lib/once.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/lib/once.c b/lib/once.c
new file mode 100644
index 000000000000..2d5a7de17aba
--- /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);