Re: [2.6.7-bk] NFS-related kernel panic

[Arthur Kepner <akepner@sgi.com>]

On Mon, 21 Jun 2004, Chris Wright wrote:

>
> The lockless loopback transmission patch mucks up the preempt count.
> Can you give this patch a try?
>
> thanks,
> -chris
> --
> Linux Security Modules     http://lsm.immunix.org     http://lsm.bkbits.net
>

Yes, there's a problem with preempt count. And this patch is
the minimal fix for it.

However, Andrew Morton noted this problem already and posted
a patch to be tested yesterday. I'd like to suggest that we go
with his patch (very slightly modified) which I'll post in a few
minutes to netdev. (I will cc Chris and Bob on this too.)

--

Arthur


> ===== loopback.c 1.15 vs edited =====
> --- 1.15/drivers/net/loopback.c	2004-06-20 17:35:52 -07:00
> +++ edited/loopback.c	2004-06-21 20:23:06 -07:00
> @@ -143,10 +143,11 @@
>
>  	dev->last_rx = jiffies;
>  	if (likely(loopback_stats)) {
> -		get_cpu_ptr(loopback_stats)->rx_bytes += skb->len;
> -		get_cpu_ptr(loopback_stats)->tx_bytes += skb->len;
> -		get_cpu_ptr(loopback_stats)->rx_packets++;
> -		get_cpu_ptr(loopback_stats)->tx_packets++;
> +		struct net_device_stats *stats = get_cpu_ptr(loopback_stats);
> +		stats->rx_bytes += skb->len;
> +		stats->tx_bytes += skb->len;
> +		stats->rx_packets++;
> +		stats->tx_packets++;
>  		put_cpu_ptr(loopback_stats);
>  	}
>
>