linux-2.4.20_mvl31 OOPS ip_route_input called within ip_rt_init

Hi,

I have an embedded ppc linux which sometimes can oops at boot time if it receives a packet during ip_rt_init. There is a printk in there in the middle of initialisation of rt_hash_table which can introduce a delay which makes the problem more likely to happen,

Output before the oops:
NET4: Linux TCP/IP 1.0 for NET4.0
IP Protocols: ICMP, UDP, TCP, IGMP
IP: routing cache hash table of 4096 buckets, 32Kbytes <4>Oops: kernel access of bad area, sig: 11

Decoded trace (my arrows):

Trace; c00ffcfc <ip_route_input+40/21c> <--
Trace; c010339c <ip_rcv_finish+24c/258>
Trace; c00f0af8 <netif_receive_skb+118/224>
Trace; c00f0ca0 <process_backlog+9c/178>
Trace; c00f0e14 <net_rx_action+98/18c>
Trace; c001cfec <do_softirq+134/138>
Trace; c000723c <do_IRQ+c4/c8>
Trace; c00072c0 <preempt_intercept+80/84>
Trace; c0005ecc <ret_from_intercept+0/8c>
Trace; c0068d9c <proc_register+1c/f4>
Trace; c00173a8 <call_console_drivers+c0/160>
Trace; c00177cc <release_console_sem+84/130>
Trace; c0017630 <printk+170/1f0>
Trace; c0198294 <ip_rt_init+128/2c8> <--
Trace; c0198530 <ip_init+1c/5c>
Trace; c0198d74 <inet_init+f0/220>
Trace; c01896b0 <do_initcalls+30/50>
Trace; c0003b40 <init+28/200>
Trace; c000894c <arch_kernel_thread+30/3c>

Code:

int ip_route_input(struct sk_buff *skb, u32 daddr, u32 saddr,
u8 tos, struct net_device *dev)

{
        struct rtable * rth;
        unsigned        hash;
        int iif = dev->ifindex;

        tos &= IPTOS_RT_MASK;
        hash = rt_hash_code(daddr, saddr ^ (iif << 5), tos);

        read_lock(&rt_hash_table[hash].lock);  <-- oops here!!

[...]

void __init ip_rt_init(void)
{

[...]

        rt_hash_table = (struct rt_hash_bucket *)
            __get_free_pages(GFP_ATOMIC, order);
    } while (rt_hash_table == NULL && --order > 0);

    if (!rt_hash_table)
        panic("Failed to allocate IP route cache hash table\n");

    printk(KERN_INFO "IP: routing cache hash table of %u buckets, 
%ldKbytes\n",
           rt_hash_mask,
           (long) (rt_hash_mask * sizeof(struct rt_hash_bucket)) / 1024);

    for (rt_hash_log = 0; (1 << rt_hash_log) != rt_hash_mask; 
rt_hash_log++)
        /* NOTHING */;

    rt_hash_mask--;
    for (i = 0; i <= rt_hash_mask; i++) {
        rt_hash_table[i].lock = RW_LOCK_UNLOCKED;
        rt_hash_table[i].chain = NULL;
    }

Is this a known problem?

What can be done to prevent this? Should the device be held inactive somehow until ip_rt_init has completed? Should I just move the printk to later in the code and hope for the best?

Any info gratefully received,

-Cam

[email protected]                                                 <--

On Jul 22 2004, at 18:53, Cam was caught saying:

_Please_ do not send questions for vendor-supplied and supported kernels to this list. If you have this kernel, you are probably a MVista customer and you should go ask their support folks.

~Deepak

Deepak Saxena - dsaxena at plexity dot net - http://www.plexity.net/

"Unlike me, many of you have accepted the situation of your imprisonment and
 will die here like rotten cabbages." - Number 6