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tipc: extract bundled buffers by cloning instead of copying

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When we currently extract a bundled buffer from a message bundle in
the function tipc_msg_extract(), we allocate a new buffer and explicitly
copy the linear data area.

This is unnecessary, since we can just clone the buffer and do
skb_pull() on the clone to move the data pointer to the correct
position.

This is what we do in this commit.

Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jon Paul Maloy 2015-03-13 16:08:08 -04:00 • committed by David S. Miller
parent 1149557d64
commit c1336ee472
2 changed files with 29 additions and 48 deletions
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32
net/tipc/msg.c
View file

@ -372,38 +372,40 @@ bool tipc_msg_bundle(struct sk_buff_head *list, struct sk_buff *skb, u32 mtu)
/**
* tipc_msg_extract(): extract bundled inner packet from buffer
* @skb: linear outer buffer, to be extracted from.
* @skb: buffer to be extracted from.
* @iskb: extracted inner buffer, to be returned
* @pos: position of msg to be extracted. Returns with pointer of next msg
* @pos: position in outer message of msg to be extracted.
* Returns position of next msg
* Consumes outer buffer when last packet extracted
* Returns true when when there is an extracted buffer, otherwise false
*/
bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos)
{
struct tipc_msg *msg;
int imsz;
struct tipc_msg *imsg;
int imsz, offset;
*iskb = NULL;
if (unlikely(skb_linearize(skb)))
return false;
msg = buf_msg(skb);
imsg = (struct tipc_msg *)(msg_data(msg) + *pos);
/* Is there space left for shortest possible message? */
if (*pos > (msg_data_sz(msg) - SHORT_H_SIZE))
goto none;
imsz = msg_size(imsg);
/* Is there space left for current message ? */
if ((*pos + imsz) > msg_data_sz(msg))
msg = buf_msg(skb);
offset = msg_hdr_sz(msg) + *pos;
if (unlikely(offset > (msg_size(msg) - MIN_H_SIZE)))
goto none;
*iskb = tipc_buf_acquire(imsz);
if (!*iskb)
*iskb = skb_clone(skb, GFP_ATOMIC);
if (unlikely(!*iskb))
goto none;
skb_pull(*iskb, offset);
imsz = msg_size(buf_msg(*iskb));
skb_trim(*iskb, imsz);
if (unlikely(!tipc_msg_validate(*iskb)))
goto none;
skb_copy_to_linear_data(*iskb, imsg, imsz);
*pos += align(imsz);
return true;
none:
kfree_skb(skb);
kfree_skb(*iskb);
*iskb = NULL;
return false;
}