[PATCH] net: llc: drop VLA in llc_sap_mcast()

From: Salvatore Mesoraca
Date: Sun Mar 11 2018 - 17:12:41 EST


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@xxxxxxxxx>
---
net/llc/llc_sap.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
index d90928f..a7f7b8f 100644
--- 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);
--
1.9.1