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authorHerbert Xu <herbert@gondor.apana.org.au>2005-12-13 23:16:37 -0800
committerDavid S. Miller <davem@sunset.davemloft.net>2006-01-03 13:10:41 -0800
commit3305b80c214c642b89cd5c21af83bc91ec13f8bd (patch)
tree909ed75c500d0ac422738781f84a819c933703c5 /net/core
parent57cca05af1e20fdc65b55be52c042c234f86c866 (diff)
[IP]: Simplify and consolidate MSG_PEEK error handling
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>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/datagram.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 1bcfef51ac5..f8d322e1ea9 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -47,6 +47,7 @@
#include <linux/rtnetlink.h>
#include <linux/poll.h>
#include <linux/highmem.h>
+#include <linux/spinlock.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
@@ -200,6 +201,41 @@ void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
}
/**
+ * skb_kill_datagram - Free a datagram skbuff forcibly
+ * @sk: socket
+ * @skb: datagram skbuff
+ * @flags: MSG_ flags
+ *
+ * This function frees a datagram skbuff that was received by
+ * skb_recv_datagram. The flags argument must match the one
+ * used for skb_recv_datagram.
+ *
+ * If the MSG_PEEK flag is set, and the packet is still on the
+ * receive queue of the socket, it will be taken off the queue
+ * before it is freed.
+ *
+ * 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.
+ */
+
+void skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
+{
+ if (flags & MSG_PEEK) {
+ 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);
+ }
+ spin_unlock_bh(&sk->sk_receive_queue.lock);
+ }
+
+ kfree_skb(skb);
+}
+
+EXPORT_SYMBOL(skb_kill_datagram);
+
+/**
* skb_copy_datagram_iovec - Copy a datagram to an iovec.
* @skb: buffer to copy
* @offset: offset in the buffer to start copying from