net: core: Specify skb_pad()/skb_put_padto() SKB freeing

Rename skb_pad() into __skb_pad() and make it take a third argument:
free_on_error which controls whether kfree_skb() should be called or
not, skb_pad() directly makes use of it and passes true to preserve its
existing behavior. Do exactly the same thing with __skb_put_padto() and
skb_put_padto().

Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Woojung Huh <Woojung.Huh@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index dbe29b6..d67a818 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -973,7 +973,23 @@ int __must_check skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg
 int __must_check skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg,
                              int offset, int len);
 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
-int skb_pad(struct sk_buff *skb, int pad);
+int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error);
+
+/**
+ *     skb_pad                 -       zero pad the tail of an skb
+ *     @skb: buffer to pad
+ *     @pad: space to pad
+ *
+ *     Ensure that a buffer is followed by a padding area that is zero
+ *     filled. Used by network drivers which may DMA or transfer data
+ *     beyond the buffer end onto the wire.
+ *
+ *     May return error in out of memory cases. The skb is freed on error.
+ */
+static inline int skb_pad(struct sk_buff *skb, int pad)
+{
+       return __skb_pad(skb, pad, true);
+}
 #define dev_kfree_skb(a)       consume_skb(a)
 
 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
@@ -2825,25 +2841,42 @@ static inline int skb_padto(struct sk_buff *skb, unsigned int len)
  *     skb_put_padto - increase size and pad an skbuff up to a minimal size
  *     @skb: buffer to pad
  *     @len: minimal length
+ *     @free_on_error: free buffer on error
  *
  *     Pads up a buffer to ensure the trailing bytes exist and are
  *     blanked. If the buffer already contains sufficient data it
  *     is untouched. Otherwise it is extended. Returns zero on
- *     success. The skb is freed on error.
+ *     success. The skb is freed on error if @free_on_error is true.
  */
-static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
+static inline int __skb_put_padto(struct sk_buff *skb, unsigned int len,
+                                 bool free_on_error)
 {
        unsigned int size = skb->len;
 
        if (unlikely(size < len)) {
                len -= size;
-               if (skb_pad(skb, len))
+               if (__skb_pad(skb, len, free_on_error))
                        return -ENOMEM;
                __skb_put(skb, len);
        }
        return 0;
 }
 
+/**
+ *     skb_put_padto - increase size and pad an skbuff up to a minimal size
+ *     @skb: buffer to pad
+ *     @len: minimal length
+ *
+ *     Pads up a buffer to ensure the trailing bytes exist and are
+ *     blanked. If the buffer already contains sufficient data it
+ *     is untouched. Otherwise it is extended. Returns zero on
+ *     success. The skb is freed on error.
+ */
+static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
+{
+       return __skb_put_padto(skb, len, true);
+}
+
 static inline int skb_add_data(struct sk_buff *skb,
                               struct iov_iter *from, int copy)
 {

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f990eb8..e075566 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1363,18 +1363,20 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
 EXPORT_SYMBOL(skb_copy_expand);
 
 /**
- *     skb_pad                 -       zero pad the tail of an skb
+ *     __skb_pad               -       zero pad the tail of an skb
  *     @skb: buffer to pad
  *     @pad: space to pad
+ *     @free_on_error: free buffer on error
  *
  *     Ensure that a buffer is followed by a padding area that is zero
  *     filled. Used by network drivers which may DMA or transfer data
  *     beyond the buffer end onto the wire.
  *
- *     May return error in out of memory cases. The skb is freed on error.
+ *     May return error in out of memory cases. The skb is freed on error
+ *     if @free_on_error is true.
  */
 
-int skb_pad(struct sk_buff *skb, int pad)
+int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
 {
        int err;
        int ntail;
@@ -1403,10 +1405,11 @@ int skb_pad(struct sk_buff *skb, int pad)
        return 0;
 
 free_skb:
-       kfree_skb(skb);
+       if (free_on_error)
+               kfree_skb(skb);
        return err;
 }
-EXPORT_SYMBOL(skb_pad);
+EXPORT_SYMBOL(__skb_pad);
 
 /**
  *     pskb_put - add data to the tail of a potentially fragmented buffer