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[IP]: Simplify and consolidate MSG_PEEK error handling

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When a packet is obtained from skb_recv_datagram with MSG_PEEK enabled
it is left on the socket receive queue.  This means that when we detect
a checksum error we have to be careful when trying to free the packet
as someone could have dequeued it in the time being.

Currently this delicate logic is duplicated three times between UDPv4,
UDPv6 and RAWv6.  This patch moves them into a one place and simplifies
the code somewhat.

This is based on a suggestion by Eric Dumazet.

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
2005-12-13 23:16:37 -08:00
committed by David S. Miller
parent 57cca05af1
commit 3305b80c21
5 changed files with 44 additions and 41 deletions
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16
net/ipv6/raw.c
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@ -32,6 +32,7 @@
#include <linux/icmpv6.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>
#include <linux/skbuff.h>
#include <asm/uaccess.h>
#include <asm/ioctls.h>
#include <asm/bug.h>
@ -433,25 +434,14 @@ out:
return err;
csum_copy_err:
/* Clear queue. */
if (flags&MSG_PEEK) {
int clear = 0;
spin_lock_bh(&sk->sk_receive_queue.lock);
if (skb == skb_peek(&sk->sk_receive_queue)) {
__skb_unlink(skb, &sk->sk_receive_queue);
clear = 1;
}
spin_unlock_bh(&sk->sk_receive_queue.lock);
if (clear)
kfree_skb(skb);
}
skb_kill_datagram(sk, skb, flags);
/* Error for blocking case is chosen to masquerade
as some normal condition.
*/
err = (flags&MSG_DONTWAIT) ? -EAGAIN : -EHOSTUNREACH;
/* FIXME: increment a raw6 drops counter here */
goto out_free;
goto out;
}
static int rawv6_push_pending_frames(struct sock *sk, struct flowi *fl,