Subject: Re: [PATCH] net: marvell: mvneta: fix DMA debug warning

From: Gregory CLEMENT <[email-masked]>
Date: Fri, 15 Feb 2019 15:31:06 +0100

Hi Russell,
 
 On ven., févr. 15 2019, Russell King <[email-masked]> wrote:

> Booting 4.20 on SolidRun Clearfog issues this warning with DMA API
> debug enabled:
>
> WARNING: CPU: 0 PID: 555 at kernel/dma/debug.c:1230 check_sync+0x514/0x5bc
> mvneta f1070000.ethernet: DMA-API: device driver tries to sync DMA memory it has not allocated [device address=0x000000002dd7dc00] [size=240 bytes]
> Modules linked in: ahci mv88e6xxx dsa_core xhci_plat_hcd xhci_hcd devlink armada_thermal marvell_cesa des_generic ehci_orion phy_armada38x_comphy mcp3021 spi_orion evbug sfp mdio_i2c ip_tables x_tables
> CPU: 0 PID: 555 Comm: bridge-network- Not tainted 4.20.0+ #291
> Hardware name: Marvell Armada 380/385 (Device Tree)
> [<c0019638>] (unwind_backtrace) from [<c0014888>] (show_stack+0x10/0x14)
> [<c0014888>] (show_stack) from [<c07f54e0>] (dump_stack+0x9c/0xd4)
> [<c07f54e0>] (dump_stack) from [<c00312bc>] (__warn+0xf8/0x124)
> [<c00312bc>] (__warn) from [<c00313b0>] (warn_slowpath_fmt+0x38/0x48)
> [<c00313b0>] (warn_slowpath_fmt) from [<c00b0370>] (check_sync+0x514/0x5bc)
> [<c00b0370>] (check_sync) from [<c00b04f8>] (debug_dma_sync_single_range_for_cpu+0x6c/0x74)
> [<c00b04f8>] (debug_dma_sync_single_range_for_cpu) from [<c051bd14>] (mvneta_poll+0x298/0xf58)
> [<c051bd14>] (mvneta_poll) from [<c0656194>] (net_rx_action+0x128/0x424)
> [<c0656194>] (net_rx_action) from [<c000a230>] (__do_softirq+0xf0/0x540)
> [<c000a230>] (__do_softirq) from [<c00386e0>] (irq_exit+0x124/0x144)
> [<c00386e0>] (irq_exit) from [<c009b5e0>] (__handle_domain_irq+0x58/0xb0)
> [<c009b5e0>] (__handle_domain_irq) from [<c03a63c4>] (gic_handle_irq+0x48/0x98)
> [<c03a63c4>] (gic_handle_irq) from [<c0009a10>] (__irq_svc+0x70/0x98)
> ...
>
> This appears to be caused by mvneta_rx_hwbm() calling
> dma_sync_single_range_for_cpu() with the wrong struct device pointer,
> as the buffer manager device pointer is used to map and unmap the
> buffer.  Fix this.
>

For me it makes sens to associate the DMA buffer to the HWBM, so this
fixes looks good for me.

Reviwed-by: Gregory CLEMENT <[email-masked]>

Thanks,

Gregory

> Signed-off-by: Russell King <[email-masked]>
> ---
> Please check that this is the correct fix.
>
>  drivers/net/ethernet/marvell/mvneta.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index ef0a85bbc586..0e1f87fca952 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -2086,7 +2086,7 @@ static int mvneta_rx_hwbm(struct napi_struct *napi,
>  			if (unlikely(!skb))
>  				goto err_drop_frame_ret_pool;
>  
> -			dma_sync_single_range_for_cpu(dev->dev.parent,
> +			dma_sync_single_range_for_cpu(&pp->bm_priv->pdev->dev,
>  			                              rx_desc->buf_phys_addr,
>  			                              MVNETA_MH_SIZE + NET_SKB_PAD,
>  			                              rx_bytes,
> -- 
> 2.7.4
>

-- 
Gregory Clement, Bootlin
Embedded Linux and Kernel engineering
http://bootlin.com