netdev - Re: [PATCH net-next-2.6] sfq: fix slot_dequeue

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Message-ID: <1293744669.2973.12.camel@edumazet-laptop>
Date:	Thu, 30 Dec 2010 22:31:09 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next-2.6] sfq: fix slot_dequeue_head()

Le jeudi 30 décembre 2010 à 18:49 +0100, Jarek Poplawski a écrit :

> Nice scenario ;-) Of course, it's easy to guess I looked for something
> like this after your previous fix and missed that :-| Btw, it looks
> like slot_queue_init() could go back to sfq_init() now.
> 

Indeed, I tested following combined patch and all is good.

Thanks Jarek !

[PATCH v2 net-next-2.6] sfq: fix slot_dequeue_head()

slot_dequeue_head() should make sure slot skb chain is correct in both
ways, or we can crash if all possible flows are in use.

Jarek pointed out slot_queue_init() can now be done in sfq_init() once,
instead each time a flow is setup.

Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
Cc: Jarek Poplawski <jarkao2@...il.com>
---
 net/sched/sch_sfq.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 6a2f88f..02fa1dd 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -292,6 +292,7 @@ static inline struct sk_buff *slot_dequeue_head(struct sfq_slot *slot)
 	struct sk_buff *skb = slot->skblist_next;
 
 	slot->skblist_next = skb->next;
+	skb->next->prev = (struct sk_buff *)slot;
 	skb->next = skb->prev = NULL;
 	return skb;
 }
@@ -375,7 +376,6 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 		q->ht[hash] = x;
 		slot = &q->slots[x];
 		slot->hash = hash;
-		slot_queue_init(slot);
 	}
 
 	/* If selected queue has length q->limit, do simple tail drop,
@@ -533,8 +533,10 @@ static int sfq_init(struct Qdisc *sch, struct nlattr *opt)
 			return err;
 	}
 
-	for (i = 0; i < SFQ_SLOTS; i++)
+	for (i = 0; i < SFQ_SLOTS; i++) {
+		slot_queue_init(&q->slots[i]);
 		sfq_link(q, i);
+	}
 	return 0;
 }
 


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