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Diffstat (limited to 'drivers/net/wireguard/send.c')
-rw-r--r--drivers/net/wireguard/send.c16
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/net/wireguard/send.c b/drivers/net/wireguard/send.c
index c13260563446..7348c10cbae3 100644
--- a/drivers/net/wireguard/send.c
+++ b/drivers/net/wireguard/send.c
@@ -143,16 +143,22 @@ static void keep_key_fresh(struct wg_peer *peer)
static unsigned int calculate_skb_padding(struct sk_buff *skb)
{
+ unsigned int padded_size, last_unit = skb->len;
+
+ if (unlikely(!PACKET_CB(skb)->mtu))
+ return ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE) - last_unit;
+
/* We do this modulo business with the MTU, just in case the networking
* layer gives us a packet that's bigger than the MTU. In that case, we
* wouldn't want the final subtraction to overflow in the case of the
- * padded_size being clamped.
+ * padded_size being clamped. Fortunately, that's very rarely the case,
+ * so we optimize for that not happening.
*/
- unsigned int last_unit = skb->len % PACKET_CB(skb)->mtu;
- unsigned int padded_size = ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE);
+ if (unlikely(last_unit > PACKET_CB(skb)->mtu))
+ last_unit %= PACKET_CB(skb)->mtu;
- if (padded_size > PACKET_CB(skb)->mtu)
- padded_size = PACKET_CB(skb)->mtu;
+ padded_size = min(PACKET_CB(skb)->mtu,
+ ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE));
return padded_size - last_unit;
}