net: Add skb_unclone() helper function.

This function will be used in next GRE_GSO patch. This patch does
not change any functionality.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Eric Dumazet <edumazet@google.com>

13 files changed, 23 insertions, 21 deletions

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 0b2706abe3e3..4fd754e74eb2 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -1805,8 +1805,7 @@ ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
                 /* the filter instructions are constructed assuming
                    a four-byte PPP header on each packet */
                 if (ppp->pass_filter || ppp->active_filter) {
-                        if (skb_cloned(skb) &&
-                            pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+                        if (skb_unclone(skb, GFP_ATOMIC))
                                 goto err;
 
                         *skb_push(skb, 2) = 0;
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 9da99520ccd5..ca6ee7d93edb 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -804,6 +804,16 @@ static inline int skb_cloned(const struct sk_buff *skb)
                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
 }
 
+static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
+{
+        might_sleep_if(pri & __GFP_WAIT);
+
+        if (skb_cloned(skb))
+                return pskb_expand_head(skb, 0, 0, pri);
+
+        return 0;
+}
+
 /**
  *      skb_header_cloned - is the header a clone
  *      @skb: buffer to check
diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c
index a69b4e4a02b5..2e7f1948216f 100644
--- a/net/ipv4/ah4.c
+++ b/net/ipv4/ah4.c
@@ -321,8 +321,7 @@ static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
 
         /* We are going to _remove_ AH header to keep sockets happy,
          * so... Later this can change. */
-        if (skb_cloned(skb) &&
-            pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+        if (skb_unclone(skb, GFP_ATOMIC))
                 goto out;
 
         skb->ip_summed = CHECKSUM_NONE;
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 1211613c6c34..b6d30acb600c 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -590,7 +590,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
                 goto out_oversize;
 
         /* Head of list must not be cloned. */
-        if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
+        if (skb_unclone(head, GFP_ATOMIC))
                 goto out_nomem;
 
         /* If the first fragment is fragmented itself, we split
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 6182d90e97b0..fd0cea114b5d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1331,7 +1331,7 @@ static void __pskb_trim_head(struct sk_buff *skb, int len)
 /* Remove acked data from a packet in the transmit queue. */
 int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
 {
-        if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+        if (skb_unclone(skb, GFP_ATOMIC))
                 return -ENOMEM;
 
         __pskb_trim_head(skb, len);
diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c
index 06814b6216dc..1f12c8b45864 100644
--- a/net/ipv4/xfrm4_input.c
+++ b/net/ipv4/xfrm4_input.c
@@ -132,7 +132,7 @@ int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
          * header and optional ESP marker bytes) and then modify the
          * protocol to ESP, and then call into the transform receiver.
          */
-        if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+        if (skb_unclone(skb, GFP_ATOMIC))
                 goto drop;
 
         /* Now we can update and verify the packet length... */
diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index ddee0a099a2c..1162ace30838 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -142,8 +142,7 @@ static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
         for_each_input_rcu(rcv_notify_handlers, handler)
                 handler->handler(skb);
 
-        if (skb_cloned(skb) &&
-            (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+        if (err = skb_unclone(skb, GFP_ATOMIC))
                 goto out;
 
         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
diff --git a/net/ipv6/ah6.c b/net/ipv6/ah6.c
index 384233188ac1..bb02e176cb70 100644
--- a/net/ipv6/ah6.c
+++ b/net/ipv6/ah6.c
@@ -521,8 +521,7 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 
         /* We are going to _remove_ AH header to keep sockets happy,
          * so... Later this can change. */
-        if (skb_cloned(skb) &&
-            pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+        if (skb_unclone(skb, GFP_ATOMIC))
                 goto out;
 
         skb->ip_summed = CHECKSUM_NONE;
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index c674f158efa8..b89a8c3186cd 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -368,7 +368,7 @@ nf_ct_frag6_reasm(struct frag_queue *fq, struct net_device *dev)
         }
 
         /* Head of list must not be cloned. */
-        if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) {
+        if (skb_unclone(head, GFP_ATOMIC)) {
                 pr_debug("skb is cloned but can't expand head");
                 goto out_oom;
         }
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index bab2c270f292..e354743ed426 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -404,7 +404,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
                 goto out_oversize;
 
         /* Head of list must not be cloned. */
-        if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
+        if (skb_unclone(head, GFP_ATOMIC))
                 goto out_oom;
 
         /* If the first fragment is fragmented itself, we split
diff --git a/net/ipv6/xfrm6_mode_tunnel.c b/net/ipv6/xfrm6_mode_tunnel.c
index 9f2095b19ad0..93c41a81c4c3 100644
--- a/net/ipv6/xfrm6_mode_tunnel.c
+++ b/net/ipv6/xfrm6_mode_tunnel.c
@@ -69,8 +69,7 @@ static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
                 goto out;
 
-        if (skb_cloned(skb) &&
-            (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+        if (err = skb_unclone(skb, GFP_ATOMIC))
                 goto out;
 
         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
diff --git a/net/sched/act_ipt.c b/net/sched/act_ipt.c
index 0fb9e3f567e6..e0f6de64afec 100644
--- a/net/sched/act_ipt.c
+++ b/net/sched/act_ipt.c
@@ -207,10 +207,8 @@ static int tcf_ipt(struct sk_buff *skb, const struct tc_action *a,
         struct tcf_ipt *ipt = a->priv;
         struct xt_action_param par;
 
-        if (skb_cloned(skb)) {
-                if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
-                        return TC_ACT_UNSPEC;
-        }
+        if (skb_unclone(skb, GFP_ATOMIC))
+                return TC_ACT_UNSPEC;