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authorTung Nguyen <tung.q.nguyen@dektech.com.au>2018-06-28 22:25:04 +0200
committerDavid S. Miller <davem@davemloft.net>2018-06-30 20:48:16 +0900
commitef9be755697f1b841c2a219a05df1a72ccd6f471 (patch)
treedf97059feff846ba6f30769f9096a90b4c2b29b5 /net/tipc/msg.c
parent9ca78674eb6a19acbb1d69e86273ebd1d3edf087 (diff)
downloadlinux-ef9be755697f1b841c2a219a05df1a72ccd6f471.tar.gz
tipc: eliminate buffer cloning in function tipc_msg_extract()
The function tipc_msg_extract() is using skb_clone() to clone inner messages from a message bundle buffer. Although this method is safe, it has an undesired effect that each buffer clone inherits the true-size of the bundling buffer. As a result, the buffer clone almost always ends up with being copied anyway by the message validation function. This makes the cloning into a sub-optimization. In this commit we take the consequence of this realization, and copy each inner message to a separately allocated buffer up front in the extraction function. As a bonus we can now eliminate the two cases where we had to copy re-routed packets that may potentially go out on the wire again. Signed-off-by: Tung Nguyen <tung.q.nguyen@dektech.com.au> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc/msg.c')
-rw-r--r--net/tipc/msg.c35
1 files changed, 15 insertions, 20 deletions
diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index b6c45dccba3d..b61891054709 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -416,26 +416,31 @@ bool tipc_msg_bundle(struct sk_buff *skb, struct tipc_msg *msg, u32 mtu)
*/
bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos)
{
- struct tipc_msg *msg;
- int imsz, offset;
+ struct tipc_msg *hdr, *ihdr;
+ int imsz;
*iskb = NULL;
if (unlikely(skb_linearize(skb)))
goto none;
- msg = buf_msg(skb);
- offset = msg_hdr_sz(msg) + *pos;
- if (unlikely(offset > (msg_size(msg) - MIN_H_SIZE)))
+ hdr = buf_msg(skb);
+ if (unlikely(*pos > (msg_data_sz(hdr) - MIN_H_SIZE)))
goto none;
- *iskb = skb_clone(skb, GFP_ATOMIC);
- if (unlikely(!*iskb))
+ ihdr = (struct tipc_msg *)(msg_data(hdr) + *pos);
+ imsz = msg_size(ihdr);
+
+ if ((*pos + imsz) > msg_data_sz(hdr))
goto none;
- skb_pull(*iskb, offset);
- imsz = msg_size(buf_msg(*iskb));
- skb_trim(*iskb, imsz);
+
+ *iskb = tipc_buf_acquire(imsz, GFP_ATOMIC);
+ if (!*iskb)
+ goto none;
+
+ skb_copy_to_linear_data(*iskb, ihdr, imsz);
if (unlikely(!tipc_msg_validate(iskb)))
goto none;
+
*pos += align(imsz);
return true;
none:
@@ -531,12 +536,6 @@ bool tipc_msg_reverse(u32 own_node, struct sk_buff **skb, int err)
msg_set_hdr_sz(hdr, BASIC_H_SIZE);
}
- if (skb_cloned(_skb) &&
- pskb_expand_head(_skb, BUF_HEADROOM, BUF_TAILROOM, GFP_ATOMIC))
- goto exit;
-
- /* reassign after skb header modifications */
- hdr = buf_msg(_skb);
/* Now reverse the concerned fields */
msg_set_errcode(hdr, err);
msg_set_non_seq(hdr, 0);
@@ -595,10 +594,6 @@ bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb, int *err)
if (!skb_cloned(skb))
return true;
- /* Unclone buffer in case it was bundled */
- if (pskb_expand_head(skb, BUF_HEADROOM, BUF_TAILROOM, GFP_ATOMIC))
- return false;
-
return true;
}