Hello! > From: Yoshihiro Shimoda, Sent: Friday, June 19, 2020 2:46 PM > > Hello! > > > From: Sergei Shtylyov, Sent: Monday, June 15, 2020 5:13 PM > > > > Hello! > > > > On 15.06.2020 8:58, Yoshihiro Shimoda wrote: > > > > >> From: Yoshihiro Shimoda, Sent: Tuesday, May 26, 2020 6:47 PM > > >> > > >> 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 > > >> > > >> This error means that the hardware could not change the state > > >> from "Operation" to "Configuration" while some tx queue is operating. > > >> After that, ravb_config() in ravb_dmac_init() will fail, and then > > >> any descriptors will be not allocaled anymore so that NULL porinter > > >> dereference happens after that on ravb_start_xmit(). > > >> > > >> Such a case is possible to be caused because this driver supports > > >> two queues (NC and BE) and the ravb_stop_dma() is possible to return > > >> without any stopping process if TCCR or CSR register indicates > > >> the hardware is operating for TX. > > >> > > >> To fix the issue, just try to wake the subqueue on > > >> ravb_tx_timeout_work() if the descriptors are not full instead > > >> of stop all transfers (all queues of TX and RX). > > >> > > >> [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> > > >> --- > > >> I'm guessing that this issue is possible to happen if: > > >> - ravb_start_xmit() calls netif_stop_subqueue(), and > > >> - ravb_poll() will not be called with some reason, and > > >> - netif_wake_subqueue() will be not called, and then > > >> - dev_watchdog() in net/sched/sch_generic.c calls ndo_tx_timeout(). > > >> > > >> However, unfortunately, I didn't reproduce the issue yet. > > >> To be honest, I'm also guessing other queues (SR) of this hardware > > >> which out-of tree driver manages are possible to reproduce this issue, > > >> but I didn't try such environment for now... > > >> > > >> So, I marked RFC on this patch now. > > > > > > I'm afraid, but do you have any comments about this patch? > > > > I agree that we should now reset only the stuck queue, not both but I > > doubt your solution is good enough. Let me have another look... > > Thank you for your comment! I hope this solution is good enough... I'm sorry again and again. But, do you have any time to look this patch? Best regards, Yoshihiro Shimoda
