[PATCH net] net: sgi: ioc3-eth: unregister netdev before freeing DMA rings

[PATCH net] net: sgi: ioc3-eth: unregister netdev before freeing DMA rings

[raoxu]

From: Xu Rao <raoxu@uniontech.com>

ioc3eth_remove() frees the coherent RX and TX descriptor rings before
unregistering the netdev. If the interface is running,
unregister_netdev() invokes ioc3_close() through ndo_stop.

ioc3_close() stops the device and then calls ioc3_free_rx_bufs() and
ioc3_clean_tx_ring(). Both cleanup functions access descriptors in the
rings, so the current ordering causes CPU accesses to freed coherent
memory. Until ioc3_stop() disables RX and TX DMA, the device may also
continue using the freed ring addresses.

Unregister the netdev before releasing the rings. This lets the core
close a running interface and quiesce the device while the rings are
still valid. Keep the explicit timer deletion because ndo_stop is not
called when the interface is already down.

Fixes: c7b572747549 ("net: sgi: ioc3-eth: allocate space for desc rings only once")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Rao <raoxu@uniontech.com>
---
 drivers/net/ethernet/sgi/ioc3-eth.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/sgi/ioc3-eth.c b/drivers/net/ethernet/sgi/ioc3-eth.c
index 261f2d35d579..009f37105eaf 100644
--- a/drivers/net/ethernet/sgi/ioc3-eth.c
+++ b/drivers/net/ethernet/sgi/ioc3-eth.c
@@ -967,11 +967,12 @@ static void ioc3eth_remove(struct platform_device *pdev)
 	struct net_device *dev = platform_get_drvdata(pdev);
 	struct ioc3_private *ip = netdev_priv(dev);
 
+	unregister_netdev(dev);
+	timer_delete_sync(&ip->ioc3_timer);
+
 	dma_free_coherent(ip->dma_dev, RX_RING_SIZE, ip->rxr, ip->rxr_dma);
 	dma_free_coherent(ip->dma_dev, TX_RING_SIZE + SZ_16K - 1, ip->tx_ring, ip->txr_dma);
 
-	unregister_netdev(dev);
-	timer_delete_sync(&ip->ioc3_timer);
 	free_netdev(dev);
 }
 
-- 
2.50.1

Re: [PATCH net] net: sgi: ioc3-eth: unregister netdev before freeing DMA rings

[Thomas Bogendoerfer]

On Mon, Jun 29, 2026 at 04:50:53PM +0800, raoxu wrote:
> From: Xu Rao <raoxu@uniontech.com>
> 
> ioc3eth_remove() frees the coherent RX and TX descriptor rings before
> unregistering the netdev. If the interface is running,
> unregister_netdev() invokes ioc3_close() through ndo_stop.
> 
> ioc3_close() stops the device and then calls ioc3_free_rx_bufs() and
> ioc3_clean_tx_ring(). Both cleanup functions access descriptors in the
> rings, so the current ordering causes CPU accesses to freed coherent
> memory. Until ioc3_stop() disables RX and TX DMA, the device may also
> continue using the freed ring addresses.
> 
> Unregister the netdev before releasing the rings. This lets the core
> close a running interface and quiesce the device while the rings are
> still valid. Keep the explicit timer deletion because ndo_stop is not
> called when the interface is already down.
> 
> Fixes: c7b572747549 ("net: sgi: ioc3-eth: allocate space for desc rings only once")
> Cc: stable@vger.kernel.org
> Signed-off-by: Xu Rao <raoxu@uniontech.com>
> ---
>  drivers/net/ethernet/sgi/ioc3-eth.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/sgi/ioc3-eth.c b/drivers/net/ethernet/sgi/ioc3-eth.c
> index 261f2d35d579..009f37105eaf 100644
> --- a/drivers/net/ethernet/sgi/ioc3-eth.c
> +++ b/drivers/net/ethernet/sgi/ioc3-eth.c
> @@ -967,11 +967,12 @@ static void ioc3eth_remove(struct platform_device *pdev)
>  	struct net_device *dev = platform_get_drvdata(pdev);
>  	struct ioc3_private *ip = netdev_priv(dev);
>  
> +	unregister_netdev(dev);
> +	timer_delete_sync(&ip->ioc3_timer);
> +
>  	dma_free_coherent(ip->dma_dev, RX_RING_SIZE, ip->rxr, ip->rxr_dma);
>  	dma_free_coherent(ip->dma_dev, TX_RING_SIZE + SZ_16K - 1, ip->tx_ring, ip->txr_dma);
>  
> -	unregister_netdev(dev);
> -	timer_delete_sync(&ip->ioc3_timer);
>  	free_netdev(dev);
>  }
>  
> -- 
> 2.50.1

Reviewed-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]