Re: Linux-2.6.21 hangs during post boot initialization phase

[Neil Horman <nhorman@tuxdriver.com>]

On Fri, Apr 27, 2007 at 04:05:11PM +1000, Peter Williams wrote:
> Linus Torvalds wrote:
> >
> >On Fri, 27 Apr 2007, Peter Williams wrote:
> >>The 2.6.21 kernel is hanging during the post boot phase where various 
> >>daemons
> >>are being started (not always the same daemon unfortunately).
> >>
> >>This problem was not present in 2.6.21-rc7 and there is no oops or other
> >>unusual output in the system log at the time the hang occurs.
> >
> >Can you use "git bisect" to narrow it down a bit more? It's only 125 
> >commits, so bisecting even just three or four kernels will narrow it down 
> >to a handful.
> 
> As the changes became, smaller the builds became quicker :-) and after 7 
> iterations we have:
> 
> 
> author	Neil Horman <nhorman@tuxdriver.com>
> 	Fri, 20 Apr 2007 13:54:58 +0000 (09:54 -0400)
> committer	Jeff Garzik <jeff@garzik.org>
> 	Tue, 24 Apr 2007 16:43:07 +0000 (12:43 -0400)
> commit	b748d9e3b80dc7e6ce6bf7399f57964b99a4104c
> tree	887909e1f735bb444ef0e3e370f34401fa6eee02	tree | snapshot
> parent	d91c088b39e3c66d309938de858775bb90fd1ead	commit | diff
> sis900: Allocate rx replacement buffer before rx operation
> 
> The sis900 driver appears to have a bug in which the receive routine
> passes the skbuff holding the received frame to the network stack before
> refilling the buffer in the rx ring.  If a new skbuff cannot be 
> allocated, the
> driver simply leaves a hole in the rx ring, which causes the driver to stop
> receiving frames and become non-recoverable without an rmmod/insmod 
> according to
> reporters.  This patch reverses that order, attempting to allocate a 
> replacement
> buffer first, and receiving the new frame only if one can be allocated. 
>  If no
> skbuff can be allocated, the current skbuf in the rx ring is recycled, 
> dropping
> the current frame, but keeping the NIC operational.
> 
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> Signed-off-by: Jeff Garzik <jeff@garzik.org>
> 
> Peter
> -- 
> Peter Williams                                   pwil3058@bigpond.net.au
> 
> "Learning, n. The kind of ignorance distinguishing the studious."
>  -- Ambrose Bierce

This was reported to me last night, and I've posted a patch to fix it, its
available here:
http://marc.info/?l=linux-netdev&m=117761259222165&w=2

It applies on top of the previous patch, and should fix your problem.

Here's a copy of the patch

Thanks & Regards
Neil


diff --git a/drivers/net/sis900.c b/drivers/net/sis900.c
index a6a0f09..7e44939 100644
--- a/drivers/net/sis900.c
+++ b/drivers/net/sis900.c
@@ -1754,6 +1754,7 @@ static int sis900_rx(struct net_device *net_dev)
 			sis_priv->rx_ring[entry].cmdsts = RX_BUF_SIZE;
 		} else {
 			struct sk_buff * skb;
+			struct sk_buff * rx_skb;
 
 			pci_unmap_single(sis_priv->pci_dev,
 				sis_priv->rx_ring[entry].bufptr, RX_BUF_SIZE,
@@ -1787,10 +1788,10 @@ static int sis900_rx(struct net_device *net_dev)
 			}
 
 			/* give the socket buffer to upper layers */
-			skb = sis_priv->rx_skbuff[entry];
-			skb_put(skb, rx_size);
-			skb->protocol = eth_type_trans(skb, net_dev);
-			netif_rx(skb);
+			rx_skb = sis_priv->rx_skbuff[entry];
+			skb_put(rx_skb, rx_size);
+			skb->protocol = eth_type_trans(rx_skb, net_dev);
+			netif_rx(rx_skb);
 
 			/* some network statistics */
 			if ((rx_status & BCAST) == MCAST)
-
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