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SubjectRE: [PATCH 02/14] net: axienet: Propagate failure of DMA descriptor setup
Date
> -----Original Message-----
> From: Radhey Shyam Pandey
> Sent: Friday, January 10, 2020 8:25 PM
> To: Andre Przywara <andre.przywara@arm.com>; David S . Miller
> <davem@davemloft.net>
> Cc: Michal Simek <michals@xilinx.com>; Robert Hancock
> <hancock@sedsystems.ca>; netdev@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; linux-kernel@vger.kernel.org
> Subject: RE: [PATCH 02/14] net: axienet: Propagate failure of DMA descriptor
> setup
>
> > -----Original Message-----
> > From: Andre Przywara <andre.przywara@arm.com>
> > Sent: Friday, January 10, 2020 5:24 PM
> > To: David S . Miller <davem@davemloft.net>; Radhey Shyam Pandey
> > <radheys@xilinx.com>
> > Cc: Michal Simek <michals@xilinx.com>; Robert Hancock
> > <hancock@sedsystems.ca>; netdev@vger.kernel.org; linux-arm-
> > kernel@lists.infradead.org; linux-kernel@vger.kernel.org
> > Subject: [PATCH 02/14] net: axienet: Propagate failure of DMA
> > descriptor setup
> >
> > When we fail allocating the DMA buffers in axienet_dma_bd_init(), we
> > report this error, but carry on with initialisation nevertheless.
> >
> > This leads to a kernel panic when the driver later wants to send a
> > packet, as it uses uninitialised data structures.
> >
> > Make the axienet_device_reset() routine return an error value, as it
> > contains the DMA buffer initialisation. Make sure we propagate the
> > error up the chain and eventually fail the driver initialisation, to
> > avoid relying on non-initialised buffers.
> >
> > Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
>
> > ---
> > .../net/ethernet/xilinx/xilinx_axienet_main.c | 25
> > +++++++++++++------
> > 1 file changed, 18 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> > b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> > index 20746b801959..97482cf093ce 100644
> > --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> > +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> > @@ -437,9 +437,10 @@ static void axienet_setoptions(struct net_device
> > *ndev, u32 options)
> > lp->options |= options;
> > }
> >
> > -static void __axienet_device_reset(struct axienet_local *lp)
> > +static int __axienet_device_reset(struct axienet_local *lp)
> > {
> > u32 timeout;
> > +
> > /* Reset Axi DMA. This would reset Axi Ethernet core as well. The
> > reset
> > * process of Axi DMA takes a while to complete as all pending
> > * commands/transfers will be flushed or completed during this @@
> > -455,9 +456,11 @@ static void __axienet_device_reset(struct
> > axienet_local *lp)
> > if (--timeout == 0) {
> > netdev_err(lp->ndev, "%s: DMA reset timeout!\n",
> > __func__);
> > - break;
> > + return -ETIMEDOUT;
> > }
> > }
> > +
> > + return 0;
> > }
> >
> > /**
> > @@ -471,12 +474,15 @@ static void __axienet_device_reset(struct
> > axienet_local *lp)
> > * Ethernet core. No separate hardware reset is done for the Axi Ethernet
> > * core.
> > */

Minor nit- we need to add descripton for return value.
drivers/net/ethernet/xilinx/xilinx_axienet_main.c:491: warning:
No description found for return value of 'axienet_device_reset'

> > -static void axienet_device_reset(struct net_device *ndev)
> > +static int axienet_device_reset(struct net_device *ndev)
> > {
> > u32 axienet_status;
> > struct axienet_local *lp = netdev_priv(ndev);
> > + int ret;
> >
> > - __axienet_device_reset(lp);
> > + ret = __axienet_device_reset(lp);
> > + if (ret)
> > + return ret;
> >
> > lp->max_frm_size = XAE_MAX_VLAN_FRAME_SIZE;
> > lp->options |= XAE_OPTION_VLAN;
> > @@ -491,9 +497,11 @@ static void axienet_device_reset(struct
> > net_device
> > *ndev)
> > lp->options |= XAE_OPTION_JUMBO;
> > }
> >
> > - if (axienet_dma_bd_init(ndev)) {
> > + ret = axienet_dma_bd_init(ndev);
> > + if (ret) {
> > netdev_err(ndev, "%s: descriptor allocation failed\n",
> > __func__);
> > + return ret;
> > }
> >
> > axienet_status = axienet_ior(lp, XAE_RCW1_OFFSET); @@ -518,6
> +526,8
> > @@ static void axienet_device_reset(struct net_device
> > *ndev)
> > axienet_setoptions(ndev, lp->options);
> >
> > netif_trans_update(ndev);
> > +
> > + return 0;
> > }
> >
> > /**
> > @@ -921,8 +931,9 @@ static int axienet_open(struct net_device *ndev)
> > */
> > mutex_lock(&lp->mii_bus->mdio_lock);
> > axienet_mdio_disable(lp);
> > - axienet_device_reset(ndev);
> > - ret = axienet_mdio_enable(lp);
> > + ret = axienet_device_reset(ndev);
> > + if (ret == 0)
> > + ret = axienet_mdio_enable(lp);
> > mutex_unlock(&lp->mii_bus->mdio_lock);
> > if (ret < 0)
> > return ret;
> > --
> > 2.17.1

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