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[UDP]: Only increment counter on first peek/recv

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The previous move of the the UDP inDatagrams counter caused each
peek of the same packet to be counted separately.  This may be
undesirable.

This patch fixes this by adding a bit to sk_buff to record whether
this packet has already been seen through skb_recv_datagram.  We
then only increment the counter when the packet is seen for the
first time.

The only dodgy part is the fact that skb_recv_datagram doesn't have
a good way of returning this new bit of information.  So I've added
a new function __skb_recv_datagram that does return this and made
skb_recv_datagram a wrapper around it.

The plan is to eventually replace all uses of skb_recv_datagram with
this new function at which time it can be renamed its proper name.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2007-12-05 01:53:40 -08:00 committed by David S. Miller
parent 1781f7f580
commit a59322be07
4 changed files with 39 additions and 19 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
include/linux/skbuff.h
View file

@ -288,6 +288,7 @@ struct sk_buff {
__u8 pkt_type:3,
fclone:2,
ipvs_property:1,
peeked:1,
nf_trace:1;
__be16 protocol;
@ -1538,6 +1539,8 @@ static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
skb = skb->prev)
extern struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
int *peeked, int *err);
extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
int noblock, int *err);
extern unsigned int datagram_poll(struct file *file, struct socket *sock,

41
net/core/datagram.c
View file

@ -115,10 +115,10 @@ static int wait_for_packet(struct sock *sk, int *err, long *timeo_p)
}
/**
* skb_recv_datagram - Receive a datagram skbuff
* __skb_recv_datagram - Receive a datagram skbuff
* @sk: socket
* @flags: MSG_ flags
* @noblock: blocking operation?
* @peeked: returns non-zero if this packet has been seen before
* @err: error code returned
*
* Get a datagram skbuff, understands the peeking, nonblocking wakeups
@ -143,8 +143,8 @@ static int wait_for_packet(struct sock *sk, int *err, long *timeo_p)
* quite explicitly by POSIX 1003.1g, don't change them without having
* the standard around please.
*/
struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
int noblock, int *err)
struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
int *peeked, int *err)
{
struct sk_buff *skb;
long timeo;
@ -156,7 +156,7 @@ struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
if (error)
goto no_packet;
timeo = sock_rcvtimeo(sk, noblock);
timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
do {
/* Again only user level code calls this function, so nothing
@ -165,18 +165,19 @@ struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
* Look at current nfs client by the way...
* However, this function was corrent in any case. 8)
*/
if (flags & MSG_PEEK) {
unsigned long cpu_flags;
unsigned long cpu_flags;
spin_lock_irqsave(&sk->sk_receive_queue.lock,
cpu_flags);
skb = skb_peek(&sk->sk_receive_queue);
if (skb)
spin_lock_irqsave(&sk->sk_receive_queue.lock, cpu_flags);
skb = skb_peek(&sk->sk_receive_queue);
if (skb) {
*peeked = skb->peeked;
if (flags & MSG_PEEK) {
skb->peeked = 1;
atomic_inc(&skb->users);
spin_unlock_irqrestore(&sk->sk_receive_queue.lock,
cpu_flags);
} else
skb = skb_dequeue(&sk->sk_receive_queue);
} else
__skb_unlink(skb, &sk->sk_receive_queue);
}
spin_unlock_irqrestore(&sk->sk_receive_queue.lock, cpu_flags);
if (skb)
return skb;
@ -194,6 +195,16 @@ struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
*err = error;
return NULL;
}
EXPORT_SYMBOL(__skb_recv_datagram);
struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
int noblock, int *err)
{
int peeked;
return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
&peeked, err);
}
void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
{

7
net/ipv4/udp.c
View file

@ -827,6 +827,7 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
struct sk_buff *skb;
unsigned int ulen, copied;
int peeked;
int err;
int is_udplite = IS_UDPLITE(sk);
@ -840,7 +841,8 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
return ip_recv_error(sk, msg, len);
try_again:
skb = skb_recv_datagram(sk, flags, noblock, &err);
skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
&peeked, &err);
if (!skb)
goto out;
@ -875,7 +877,8 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
if (err)
goto out_free;
UDP_INC_STATS_USER(UDP_MIB_INDATAGRAMS, is_udplite);
if (!peeked)
UDP_INC_STATS_USER(UDP_MIB_INDATAGRAMS, is_udplite);
sock_recv_timestamp(msg, sk, skb);

7
net/ipv6/udp.c
View file

@ -123,6 +123,7 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
struct inet_sock *inet = inet_sk(sk);
struct sk_buff *skb;
unsigned int ulen, copied;
int peeked;
int err;
int is_udplite = IS_UDPLITE(sk);
@ -133,7 +134,8 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
return ipv6_recv_error(sk, msg, len);
try_again:
skb = skb_recv_datagram(sk, flags, noblock, &err);
skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
&peeked, &err);
if (!skb)
goto out;
@ -166,7 +168,8 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
if (err)
goto out_free;
UDP6_INC_STATS_USER(UDP_MIB_INDATAGRAMS, is_udplite);
if (!peeked)
UDP6_INC_STATS_USER(UDP_MIB_INDATAGRAMS, is_udplite);
sock_recv_timestamp(msg, sk, skb);