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[PPPOL2TP]: Fix SMP issues in skb reorder queue handling

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When walking a session's packet reorder queue, use
skb_queue_walk_safe() since the list could be modified inside the
loop.

Rearrange the unlinking skbs from the reorder queue such that it is
done while the queue lock is held in pppol2tp_recv_dequeue() when
walking the skb list.

A version of this patch was suggested by Jarek Poplawski.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
James Chapman 2008-03-05 18:40:01 -08:00 committed by David S. Miller
parent cf3752e2d2
commit e653181dd6
1 changed files with 8 additions and 3 deletions
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11
drivers/net/pppol2tp.c
View file

@ -342,10 +342,11 @@ static struct pppol2tp_tunnel *pppol2tp_tunnel_find(u16 tunnel_id)
static void pppol2tp_recv_queue_skb(struct pppol2tp_session *session, struct sk_buff *skb)
{
struct sk_buff *skbp;
struct sk_buff *tmp;
u16 ns = PPPOL2TP_SKB_CB(skb)->ns;
spin_lock_bh(&session->reorder_q.lock);
skb_queue_walk(&session->reorder_q, skbp) {
skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
if (PPPOL2TP_SKB_CB(skbp)->ns > ns) {
__skb_insert(skb, skbp->prev, skbp, &session->reorder_q);
PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
@ -371,10 +372,9 @@ static void pppol2tp_recv_dequeue_skb(struct pppol2tp_session *session, struct s
int length = PPPOL2TP_SKB_CB(skb)->length;
struct sock *session_sock = NULL;
/* We're about to requeue the skb, so unlink it and return resources
/* We're about to requeue the skb, so return resources
* to its current owner (a socket receive buffer).
*/
skb_unlink(skb, &session->reorder_q);
skb_orphan(skb);
tunnel->stats.rx_packets++;
@ -470,6 +470,11 @@ static void pppol2tp_recv_dequeue(struct pppol2tp_session *session)
goto out;
}
}
__skb_unlink(skb, &session->reorder_q);
/* Process the skb. We release the queue lock while we
* do so to let other contexts process the queue.
*/
spin_unlock_bh(&session->reorder_q.lock);
pppol2tp_recv_dequeue_skb(session, skb);
spin_lock_bh(&session->reorder_q.lock);