netfilter: conntrack: avoid same-timeout update

No need to dirty a cache line if timeout is unchanged.
Also, WARN() is useless here: we crash on 'skb->len' access
if skb is NULL.

Last, ct->timeout is u32, not 'unsigned long' so adapt the
function prototype accordingly.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_conntrack.h

@@ -190,23 +190,23 @@ bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
 
 void __nf_ct_refresh_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 			  const struct sk_buff *skb,
-			  unsigned long extra_jiffies, int do_acct);
+			  u32 extra_jiffies, bool do_acct);
 
 /* Refresh conntrack for this many jiffies and do accounting */
 static inline void nf_ct_refresh_acct(struct nf_conn *ct,
 				      enum ip_conntrack_info ctinfo,
 				      const struct sk_buff *skb,
-				      unsigned long extra_jiffies)
+				      u32 extra_jiffies)
 {
-	__nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies, 1);
+	__nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies, true);
 }
 
 /* Refresh conntrack for this many jiffies */
 static inline void nf_ct_refresh(struct nf_conn *ct,
 				 const struct sk_buff *skb,
-				 unsigned long extra_jiffies)
+				 u32 extra_jiffies)
 {
-	__nf_ct_refresh_acct(ct, 0, skb, extra_jiffies, 0);
+	__nf_ct_refresh_acct(ct, 0, skb, extra_jiffies, false);
 }
 
 /* kill conntrack and do accounting */

net/netfilter/nf_conntrack_core.c

@@ -1751,11 +1751,9 @@ EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply);
 void __nf_ct_refresh_acct(struct nf_conn *ct,
 			  enum ip_conntrack_info ctinfo,
 			  const struct sk_buff *skb,
-			  unsigned long extra_jiffies,
-			  int do_acct)
+			  u32 extra_jiffies,
+			  bool do_acct)
 {
-	WARN_ON(!skb);
-
 	/* Only update if this is not a fixed timeout */
 	if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
 		goto acct;
@@ -1764,7 +1762,8 @@ void __nf_ct_refresh_acct(struct nf_conn *ct,
 	if (nf_ct_is_confirmed(ct))
 		extra_jiffies += nfct_time_stamp;
 
-	ct->timeout = extra_jiffies;
+	if (ct->timeout != extra_jiffies)
+		ct->timeout = extra_jiffies;
 acct:
 	if (do_acct)
 		nf_ct_acct_update(ct, ctinfo, skb->len);