net: introduce new macro net_get_random_once

[karo-tx-linux.git] / include / linux / net.h

diff --git a/include/linux/net.h b/include/linux/net.h
index ca9ec85409058e6f92248b6d98285d16a4347434..a489705f6fa3772c7012883e8b2213f0101ff38a 100644 (file)
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -239,6 +239,31 @@ do {                                                               \
 #define net_random()           prandom_u32()
 #define net_srandom(seed)      prandom_seed((__force u32)(seed))
 
+bool __net_get_random_once(void *buf, int nbytes, bool *done,
+                          struct static_key *done_key);
+
+#ifdef HAVE_JUMP_LABEL
+#define ___NET_RANDOM_STATIC_KEY_INIT ((struct static_key) \
+               { .enabled = ATOMIC_INIT(0), .entries = (void *)1 })
+#else /* !HAVE_JUMP_LABEL */
+#define ___NET_RANDOM_STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
+#endif /* HAVE_JUMP_LABEL */
+
+/* BE CAREFUL: this function is not interrupt safe */
+#define net_get_random_once(buf, nbytes)                               \
+       ({                                                              \
+               bool ___ret = false;                                    \
+               static bool ___done = false;                            \
+               static struct static_key ___done_key =                  \
+                       ___NET_RANDOM_STATIC_KEY_INIT;                  \
+               if (!static_key_true(&___done_key))                     \
+                       ___ret = __net_get_random_once(buf,             \
+                                                      nbytes,          \
+                                                      &___done,        \
+                                                      &___done_key);   \
+               ___ret;                                                 \
+       })
+
 int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,
                   size_t num, size_t len);
 int kernel_recvmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,