[INET]: Use pskb_trim_unique when trimming paged unique skbs

The IPv4/IPv6 datagram output path was using skb_trim to trim paged
packets because they know that the packet has not been cloned yet
(since the packet hasn't been given to anything else in the system).

This broke because skb_trim no longer allows paged packets to be
trimmed.  Paged packets must be given to one of the pskb_trim functions
instead.

This patch adds a new pskb_trim_unique function to cover the IPv4/IPv6
datagram output path scenario and replaces the corresponding skb_trim
calls with it.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 3573ba9a255558e3be8ea6691103306861838fe2..755e9cddac47eebe516751a55929f4339b576c5f 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1039,6 +1039,21 @@ static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
        return (len < skb->len) ? __pskb_trim(skb, len) : 0;
 }
 
+/**
+ *     pskb_trim_unique - remove end from a paged unique (not cloned) buffer
+ *     @skb: buffer to alter
+ *     @len: new length
+ *
+ *     This is identical to pskb_trim except that the caller knows that
+ *     the skb is not cloned so we should never get an error due to out-
+ *     of-memory.
+ */
+static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
+{
+       int err = pskb_trim(skb, len);
+       BUG_ON(err);
+}
+
 /**
  *     skb_orphan - orphan a buffer
  *     @skb: buffer to orphan

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 9bf307a2978355bd68fb66d663630b79720db85c..4c20f5546893dc104afd7cdf32dc4f148b38821b 100644 (file)
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -947,7 +947,7 @@ alloc_new_skb:
                                skb_prev->csum = csum_sub(skb_prev->csum,
                                                          skb->csum);
                                data += fraggap;
-                               skb_trim(skb_prev, maxfraglen);
+                               pskb_trim_unique(skb_prev, maxfraglen);
                        }
 
                        copy = datalen - transhdrlen - fraggap;
@@ -1142,7 +1142,7 @@ ssize_t   ip_append_page(struct sock *sk, struct page *page,
                                        data, fraggap, 0);
                                skb_prev->csum = csum_sub(skb_prev->csum,
                                                          skb->csum);
-                               skb_trim(skb_prev, maxfraglen);
+                               pskb_trim_unique(skb_prev, maxfraglen);
                        }
 
                        /*

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 69451af6abe7dd2aaff636498eb1894e45f43fc7..4fb47a25291313ea0851a6539bed48a73a97c1c8 100644 (file)
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1095,7 +1095,7 @@ alloc_new_skb:
                                skb_prev->csum = csum_sub(skb_prev->csum,
                                                          skb->csum);
                                data += fraggap;
-                               skb_trim(skb_prev, maxfraglen);
+                               pskb_trim_unique(skb_prev, maxfraglen);
                        }
                        copy = datalen - transhdrlen - fraggap;
                        if (copy < 0) {