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Date: Sat, 9 May 2026 18:31:47 +0200
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Subject: Re: [PATCH net-next v11 1/4] tun/tap: add ptr_ring consume helper
 with netdev queue wakeup
To: willemdebruijn.kernel@gmail.com, jasowang@redhat.com,
        andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com,
        kuba@kernel.org, pabeni@redhat.com, mst@redhat.com,
        eperezma@redhat.com, leiyang@redhat.com, stephen@networkplumber.org,
        jon@nutanix.com, tim.gebauer@tu-dortmund.de, netdev@vger.kernel.org,
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References: <20260508151048.183125-1-simon.schippers@tu-dortmund.de>
 <20260508151048.183125-2-simon.schippers@tu-dortmund.de>
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From: Simon Schippers <simon.schippers@tu-dortmund.de>
In-Reply-To: <20260508151048.183125-2-simon.schippers@tu-dortmund.de>
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On 5/8/26 17:10, Simon Schippers wrote:
> +static void tun_queue_purge(struct tun_struct *tun, struct tun_file *tfile)
>  {
>  	void *ptr;
>  
> -	while ((ptr = ptr_ring_consume(&tfile->tx_ring)) != NULL)
> +	while ((ptr = tun_ring_consume(tun, tfile)) != NULL)
>  		tun_ptr_free(ptr);
>  
>  	skb_queue_purge(&tfile->sk.sk_write_queue);

Sashiko is right once again. tun_ring_consume() in tun_queue_purge()
operates on a tfile that is being torn down. Its queue_index is no
longer valid. After the swap in __tun_detach(), it points to the
netdev subqueue of a different tfile.
--> We should not wake there.

I will swap tun_ring_consume() with ptr_ring_consume() again and
submit a v12 :)