Re: [PATCH net-next v6 4/5] net: sched: add timeout count to NETDEV WATCHDOG message

[Paolo Abeni]

On 5/27/26 3:54 PM, hawk@xxxxxxxxxx wrote:
> diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
> index 237ee1cd0136..2aebab985c00 100644
> --- a/net/sched/sch_generic.c
> +++ b/net/sched/sch_generic.c
> @@ -533,13 +533,12 @@ static void dev_watchdog(struct timer_list *t)
>  		    netif_running(dev) &&
>  		    netif_carrier_ok(dev)) {
>  			unsigned int timedout_ms = 0;
> +			struct netdev_queue *txq;
>  			unsigned int i;
>  			unsigned long trans_start;
>  			unsigned long oldest_start = jiffies;
>  
>  			for (i = 0; i < dev->num_tx_queues; i++) {
> -				struct netdev_queue *txq;
> -
>  				txq = netdev_get_tx_queue(dev, i);
>  				if (!netif_xmit_stopped(txq))
>  					continue;
> @@ -561,9 +560,10 @@ static void dev_watchdog(struct timer_list *t)
>  
>  			if (unlikely(timedout_ms)) {
>  				trace_net_dev_xmit_timeout(dev, i);
> -				netdev_crit(dev, "NETDEV WATCHDOG: CPU: %d: transmit queue %u timed out %u ms\n",
> +				netdev_crit(dev, "NETDEV WATCHDOG: CPU: %d: transmit queue %u timed out %u ms (n:%ld)\n",
>  					    raw_smp_processor_id(),
> -					    i, timedout_ms);
> +					    i, timedout_ms,
> +					    atomic_long_read(&txq->trans_timeout));

It looks like txq could be uninitialized here if num_tx_queues is 0. I'm
unsure if some weird/buggy device driver could actually hit that case,
but grep '->num_tx_queues = 0;' has more than 0 hits in the current tree
and I would err on the safe side.

/P