> Gesendet: Donnerstag, 09. Februar 2017 um 12:30 Uhr > Von: "Salil Mehta" <salil.me...@huawei.com> > An: "Lino Sanfilippo" <linosanfili...@gmx.de> > Cc: "da...@davemloft.net" <da...@davemloft.net>, "Zhuangyuzeng (Yisen)" > <yisen.zhu...@huawei.com>, "mehta.salil....@gmail.com" > <mehta.salil....@gmail.com>, "netdev@vger.kernel.org" > <netdev@vger.kernel.org>, "linux-ker...@vger.kernel.org" > <linux-ker...@vger.kernel.org>, Linuxarm <linux...@huawei.com>, "Yankejian > (Hackim Yim)" <yankej...@huawei.com> > Betreff: RE: [PATCH net] net: hns: Fix the device being used for dma mapping > during TX > > > -----Original Message----- > > From: Lino Sanfilippo [mailto:linosanfili...@gmx.de] > > Sent: Thursday, February 09, 2017 10:25 AM > > To: Salil Mehta > > Cc: da...@davemloft.net; Salil Mehta; Zhuangyuzeng (Yisen); > > mehta.salil....@gmail.com; netdev@vger.kernel.org; linux- > > ker...@vger.kernel.org; Linuxarm; Yankejian (Hackim Yim) > > Subject: Re: [PATCH net] net: hns: Fix the device being used for dma > > mapping during TX > > > > Hi, > > > > > From: Kejian Yan <yankej...@huawei.com> > > > > > > This patch fixes the device being used to DMA map skb->data. > > > Erroneous device assignment causes the crash when SMMU is enabled. > > > This happens during TX since buffer gets DMA mapped with device > > > correspondign to net_device and gets unmapped using the device > > > related to DSAF. > > > > > > Signed-off-by: Kejian Yan <yankej...@huawei.com> > > > Reviewed-by: Yisen Zhuang <yisen.zhu...@huawei.com> > > > Signed-off-by: Salil Mehta <salil.me...@huawei.com> > > > --- > > > drivers/net/ethernet/hisilicon/hns/hns_enet.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/net/ethernet/hisilicon/hns/hns_enet.c > > b/drivers/net/ethernet/hisilicon/hns/hns_enet.c > > > index 672b646..2b52a12 100644 > > > --- a/drivers/net/ethernet/hisilicon/hns/hns_enet.c > > > +++ b/drivers/net/ethernet/hisilicon/hns/hns_enet.c > > > @@ -305,7 +305,7 @@ int hns_nic_net_xmit_hw(struct net_device *ndev, > > > struct hns_nic_ring_data *ring_data) > > > { > > > struct hns_nic_priv *priv = netdev_priv(ndev); > > > - struct device *dev = priv->dev; > > > + struct device *dev = ring_to_dev(ring_data->ring); > > > struct hnae_ring *ring = ring_data->ring; > > > struct netdev_queue *dev_queue; > > > struct skb_frag_struct *frag; > > > -- > > > > I would say it should be the other way around: Use priv->dev for > > mapping and > > unmapping instead of ring_to_dev(). > Yes, you got it right. Ideally, it should be per-port and for > legacy reasons we have it this way. In the current design, we have > SMMU node per-dsaf and I guess we will not land in the right > dma-ops if we use per-netdev platform-device/device right now. >
Ok, but how can it work if we set the DMA mask of the device object of the plaform_device (via dma_set_mask_and_coherent in the probe() function) and do the actual mapping with a different device object? I dont know much about the low level dma handling but I can imagine that the mask is required to do the mapping correctly. Regards, Lino
