Hello! On 7/20/20 2:58 PM, Yoshihiro Shimoda wrote: > According to the report of [1], this driver is possible to cause > the following error in ravb_tx_timeout_work(). > > ravb e6800000.ethernet ethernet: failed to switch device to config mode Hmm, maybe we need a larger timeout there? The current one amounts to only ~100 ms for all cases (maybe we should parametrize the timeout?)... > This error means that the hardware could not change the state > from "Operation" to "Configuration" while some tx and/or rx queue > are operating. After that, ravb_config() in ravb_dmac_init() will fail, Are we seeing double messages from ravb_config()? I think we aren't... > and then any descriptors will be not allocaled anymore so that NULL > pointer dereference happens after that on ravb_start_xmit(). > > To fix the issue, the ravb_tx_timeout_work() should check > the return value of ravb_stop_dma() whether this hardware can be > re-initialized or not. If ravb_stop_dma() fails, ravb_tx_timeout_work() > re-enables TX and RX and just exits. > > [1] > https://lore.kernel.org/linux-renesas-soc/20200518045452.2390-1-dirk.behme@xxxxxxxxxxxx/ > > Reported-by: Dirk Behme <dirk.behme@xxxxxxxxxxxx> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> Assuming the comment below is fixed: Reviewed-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxx> > --- > Changes from RFC v1: > - Check the return value of ravb_stop_dma() and exit if the hardware > condition can not be initialized in the tx timeout. > - Update the commit subject and description. > - Fix some typo. > https://patchwork.kernel.org/patch/11570217/ > > Unfortunately, I still didn't reproduce the issue yet. So, I still > marked RFC on this patch. I think the Bosch people should test this patch, as they reported the kernel oops... > > drivers/net/ethernet/renesas/ravb_main.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c > index a442bcf6..500f5c1 100644 > --- a/drivers/net/ethernet/renesas/ravb_main.c > +++ b/drivers/net/ethernet/renesas/ravb_main.c > @@ -1458,7 +1458,18 @@ static void ravb_tx_timeout_work(struct work_struct *work) > ravb_ptp_stop(ndev); > > /* Wait for DMA stopping */ > - ravb_stop_dma(ndev); > + if (ravb_stop_dma(ndev)) { > + /* If ravb_stop_dma() fails, the hardware is still in-progress > + * as "Operation" mode for TX and/or RX. So, this should not s/in-progress as "Operation" mode/operating/. > + * call the following functions because ravb_dmac_init() is > + * possible to fail too. Also, this should not retry > + * ravb_stop_dma() again and again here because it's possible > + * to wait forever. So, this just re-enables the TX and RX and > + * skip the following re-initialization procedure. > + */ > + ravb_rcv_snd_enable(ndev); > + goto out; > + } > > ravb_ring_free(ndev, RAVB_BE); > ravb_ring_free(ndev, RAVB_NC); > @@ -1467,6 +1478,7 @@ static void ravb_tx_timeout_work(struct work_struct *work) > ravb_dmac_init(ndev); BTW, that one also may fail... > ravb_emac_init(ndev); > > +out: > /* Initialise PTP Clock driver */ > if (priv->chip_id == RCAR_GEN2) > ravb_ptp_init(ndev, priv->pdev); >
