net: llc: drop VLA in llc_sap_mcast()

Avoid a VLA[1] by using a real constant expression instead of a variable.
The compiler should be able to optimize the original code and avoid using
an actual VLA. Anyway this change is useful because it will avoid a false
positive with -Wvla, it might also help the compiler generating better
code.

[1] https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
index d90928f..a7f7b8f 100644 (file)
--- a/net/llc/llc_sap.c
+++ b/net/llc/llc_sap.c
@@ -394,8 +394,9 @@ static void llc_sap_mcast(struct llc_sap *sap,
                          const struct llc_addr *laddr,
                          struct sk_buff *skb)
 {
-       int i = 0, count = 256 / sizeof(struct sock *);
-       struct sock *sk, *stack[count];
+       int i = 0;
+       struct sock *sk;
+       struct sock *stack[256 / sizeof(struct sock *)];
        struct llc_sock *llc;
        struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
 
@@ -408,7 +409,7 @@ static void llc_sap_mcast(struct llc_sap *sap,
                        continue;
 
                sock_hold(sk);
-               if (i < count)
+               if (i < ARRAY_SIZE(stack))
                        stack[i++] = sk;
                else {
                        llc_do_mcast(sap, skb, stack, i);