Jarek Poplawski wrote:
Jarek Poplawski wrote, On 02/25/2008 02:39 PM:
...
Hmm... Wait a minute! But on the other hand David has written about
his cons here, and it looks reasonable: this place would be fixed,
but some others can start reports like this. Maybe, it's better to
analyze yet if it's really so hard to eliminate taking this lock
on the xmit path?
James, I wonder if you could try to test this patch below?
ip_queue_xmit() seems to do proper things with __sk_dst_check(), and
if some other functions don't behave similarly lockdep should tell.
I think, you could test it with your "locks to _bh" patch (without
pppol2tp_xmit() part), and maybe with my sock.c lockdep patch (it
should help lockdep to see these locks a bit more distinctly).
I found the same thing and was running a variant of your patch last
night; rather than set skb->dst to NULL though, I use __sk_dst_get() and
let ip_queue_xmit() do the route lookup if it returns NULL. But this has
the same symptoms as the code I tried a few days ago - no lockdep errors
but a system lockup after up to several hours. Nothing is logged in the
syslog.
Luckily, I'm in the lab where my two borrowed servers are today so I
have access to their consoles. Hopefully I'll be able to find out why
there are hanging. Btw, they don't hang if I disable irqs around the
ppp_input() call.
Will update you later.
/james
PS: Since ppp_generic isn't endangered for now I removed Paul from CC.
---
diff --git a/drivers/net/pppol2tp.c b/drivers/net/pppol2tp.c
index e0b072d..b94659a 100644
--- a/drivers/net/pppol2tp.c
+++ b/drivers/net/pppol2tp.c
@@ -1058,7 +1058,7 @@ static int pppol2tp_xmit(struct ppp_channel *chan, struct
sk_buff *skb)
/* Get routing info from the tunnel socket */
dst_release(skb->dst);
- skb->dst = sk_dst_get(sk_tun);
+ skb->dst = NULL;
skb_orphan(skb);
skb->sk = sk_tun;
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--
James Chapman
Katalix Systems Ltd
http://www.katalix.com
Catalysts for your Embedded Linux software development
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