netdev - Re: [PATCH v2] can: j1939: transport: replace kfree_skb() with dev_kfree_skb

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Message-ID: <20221027112955.GA17401@pengutronix.de>
Date:   Thu, 27 Oct 2022 13:29:55 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Yang Yingliang <yangyingliang@...wei.com>
Cc:     linux-can@...r.kernel.org, netdev@...r.kernel.org,
        robin@...tonic.nl, linux@...pel-privat.de, kernel@...gutronix.de,
        socketcan@...tkopp.net, mkl@...gutronix.de
Subject: Re: [PATCH v2] can: j1939: transport: replace kfree_skb() with
 dev_kfree_skb_irq()

On Thu, Oct 27, 2022 at 05:12:37PM +0800, Yang Yingliang wrote:
> It is not allowed to call kfree_skb() from hardware interrupt
> context or with interrupts being disabled. The skb is unlinked
> from the queue, so it can be freed after spin_unlock_irqrestore().
> 
> Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>

Acked-by: Oleksij Rempel <o.rempel@...gutronix.de>

> ---
> v1 -> v2:
>   Move kfree_skb() after spin_unlock_irqrestore().
> ---
>  net/can/j1939/transport.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
> index d7d86c944d76..55f29c9f9e08 100644
> --- a/net/can/j1939/transport.c
> +++ b/net/can/j1939/transport.c
> @@ -342,10 +342,12 @@ static void j1939_session_skb_drop_old(struct j1939_session *session)
>  		__skb_unlink(do_skb, &session->skb_queue);
>  		/* drop ref taken in j1939_session_skb_queue() */
>  		skb_unref(do_skb);
> +		spin_unlock_irqrestore(&session->skb_queue.lock, flags);
>  
>  		kfree_skb(do_skb);
> +	} else {
> +		spin_unlock_irqrestore(&session->skb_queue.lock, flags);
>  	}
> -	spin_unlock_irqrestore(&session->skb_queue.lock, flags);
>  }
>  
>  void j1939_session_skb_queue(struct j1939_session *session,
> -- 
> 2.25.1
> 
> 

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