Re: [PATCH net v3 2/2] net: ethernet: oa_tc6: fix tx skb race condition between reference pointers

[Parthiban.Veerasooran]

Hi Jakub,

On 10/12/24 5:41 am, Jakub Kicinski wrote:
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> 
> On Wed, 4 Dec 2024 19:05:18 +0530 Parthiban Veerasooran wrote:
>> @@ -1210,7 +1213,9 @@ netdev_tx_t oa_tc6_start_xmit(struct oa_tc6 *tc6, struct sk_buff *skb)
>>                return NETDEV_TX_OK;
>>        }
>>
>> +     mutex_lock(&tc6->tx_skb_lock);
>>        tc6->waiting_tx_skb = skb;
>> +     mutex_unlock(&tc6->tx_skb_lock);
> 
> start_xmit runs in BH / softirq context. You can't take sleeping locks.
> The lock has to be a spin lock. You could possibly try to use the
> existing spin lock of the tx queue (__netif_tx_lock()) but that may be
> more challenging to do cleanly from within a library..
Thanks for the input. Yes, it looks like implementing a spin lock would 
be a right choice. I will implement it and do the testing as you 
suggested below and share the feedback.

Best regards,
Parthiban V
> 
> Please make sure you test with builds including the
> kernel/configs/debug.config Kconfigs.
> --
> pw-bot: cr