[UDP]: Avoid repeated counting of checksum errors due to peeking
Currently it is possible for two processes to peek on the same socket
and end up incrementing the error counter twice for the same packet.
This patch fixes it by making skb_kill_datagram return whether it
succeeded in unlinking the packet and only incrementing the counter
if it did.
Signed-off-by: Herbert Xu <[EMAIL PROTECTED]>
---
include/linux/skbuff.h | 2 +-
net/core/datagram.c | 9 ++++++++-
net/ipv4/udp.c | 5 ++---
net/ipv6/udp.c | 4 ++--
4 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1552,7 +1552,7 @@ extern int skb_copy_and_csum_data
int hlen,
struct iovec *iov);
extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
-extern void skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
+extern int skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
unsigned int flags);
extern __wsum skb_checksum(const struct sk_buff *skb, int offset,
int len, __wsum csum);
diff --git a/net/core/datagram.c b/net/core/datagram.c
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -217,20 +217,27 @@ void skb_free_datagram(struct sock *sk,
* This function currently only disables BH when acquiring the
* sk_receive_queue lock. Therefore it must not be used in a
* context where that lock is acquired in an IRQ context.
+ *
+ * It returns 0 if the packet was removed by us.
*/
-void skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int
flags)
+int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
{
+ int err = 0;
+
if (flags & MSG_PEEK) {
+ err = -ENOENT;
spin_lock_bh(&sk->sk_receive_queue.lock);
if (skb == skb_peek(&sk->sk_receive_queue)) {
__skb_unlink(skb, &sk->sk_receive_queue);
atomic_dec(&skb->users);
+ err = 0;
}
spin_unlock_bh(&sk->sk_receive_queue.lock);
}
kfree_skb(skb);
+ return err;
}
EXPORT_SYMBOL(skb_kill_datagram);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -899,9 +899,8 @@ out:
return err;
csum_copy_err:
- UDP_INC_STATS_USER(UDP_MIB_INERRORS, is_udplite);
-
- skb_kill_datagram(sk, skb, flags);
+ if (!skb_kill_datagram(sk, skb, flags))
+ UDP_INC_STATS_USER(UDP_MIB_INERRORS, is_udplite);
if (noblock)
return -EAGAIN;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -207,8 +207,8 @@ out:
return err;
csum_copy_err:
- UDP6_INC_STATS_USER(UDP_MIB_INERRORS, is_udplite);
- skb_kill_datagram(sk, skb, flags);
+ if (!skb_kill_datagram(sk, skb, flags))
+ UDP6_INC_STATS_USER(UDP_MIB_INERRORS, is_udplite);
if (flags & MSG_DONTWAIT)
return -EAGAIN;
--
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <[EMAIL PROTECTED]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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