linux-kernel - Re: [PATCH 1/1] net: macb: fix the RX queue reset in macb

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Message-ID: <8c91d53a-3556-4305-ce9d-589753445e19@atmel.com>
Date:   Fri, 25 Nov 2016 10:11:20 +0100
From:   Nicolas Ferre <nicolas.ferre@...el.com>
To:     Cyrille Pitchen <cyrille.pitchen@...el.com>, <davem@...emloft.net>,
        <netdev@...r.kernel.org>, <soren.brinkmann@...inx.com>
CC:     <Andrei.Pistirica@...rochip.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] net: macb: fix the RX queue reset in macb_rx()

Le 25/11/2016 à 09:49, Cyrille Pitchen a écrit :
> On macb only (not gem), when a RX queue corruption was detected from
> macb_rx(), the RX queue was reset: during this process the RX ring
> buffer descriptor was initialized by macb_init_rx_ring() but we forgot
> to also set bp->rx_tail to 0.
> 
> Indeed, when processing the received frames, bp->rx_tail provides the
> macb driver with the index in the RX ring buffer of the next buffer to
> process. So when the whole ring buffer is reset we must also reset
> bp->rx_tail so the driver is synchronized again with the hardware.
> 
> Since macb_init_rx_ring() is called from many locations, currently from
> macb_rx() and macb_init_rings(), we'd rather add the "bp->rx_tail = 0;"
> line inside macb_init_rx_ring() than add the very same line after each
> call of this function.
> 
> Without this fix, the rx queue is not reset properly to recover from
> queue corruption and connection drop may occur.
> 
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@...el.com>
> Fixes: 9ba723b081a2 ("net: macb: remove BUG_ON() and reset the queue to handle RX errors")

Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
Thanks.

Regards,

> ---
>  drivers/net/ethernet/cadence/macb.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
> index 0e489bb82456..8ee303b8da08 100644
> --- a/drivers/net/ethernet/cadence/macb.c
> +++ b/drivers/net/ethernet/cadence/macb.c
> @@ -991,6 +991,7 @@ static inline void macb_init_rx_ring(struct macb *bp)
>  		addr += bp->rx_buffer_size;
>  	}
>  	bp->rx_ring[bp->rx_ring_size - 1].addr |= MACB_BIT(RX_WRAP);
> +	bp->rx_tail = 0;
>  }
>  
>  static int macb_rx(struct macb *bp, int budget)
> @@ -1736,8 +1737,6 @@ static void macb_init_rings(struct macb *bp)
>  	bp->queues[0].tx_head = 0;
>  	bp->queues[0].tx_tail = 0;
>  	bp->queues[0].tx_ring[bp->tx_ring_size - 1].ctrl |= MACB_BIT(TX_WRAP);
> -
> -	bp->rx_tail = 0;
>  }
>  
>  static void macb_reset_hw(struct macb *bp)
> 


-- 
Nicolas Ferre