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Date: Thu, 22 Oct 2020 17:15:23 -0700 From: Moritz Fischer <mdf@...nel.org> To: James Bottomley <James.Bottomley@...senpartnership.com> Cc: Moritz Fischer <mdf@...nel.org>, netdev@...r.kernel.org, davem@...emloft.net, linux-parisc@...r.kernel.org, linux-kernel@...r.kernel.org, lucyyan@...gle.com Subject: Re: [PATCH/RFC net] net: dec: tulip: de2104x: Add shutdown handler to stop NIC On Thu, Oct 22, 2020 at 04:04:16PM -0700, James Bottomley wrote: > On Thu, 2020-10-22 at 15:06 -0700, Moritz Fischer wrote: > > The driver does not implement a shutdown handler which leads to > > issues > > when using kexec in certain scenarios. The NIC keeps on fetching > > descriptors which gets flagged by the IOMMU with errors like this: > > > > DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000 > > DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000 > > DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000 > > DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000 > > DMAR: DMAR:[DMA read] Request device [5e:00.0]fault addr fffff000 > > > > Signed-off-by: Moritz Fischer <mdf@...nel.org> > > --- > > > > Hi all, > > > > I'm not sure if this is the proper way for a shutdown handler, > > I've tried to look at a bunch of examples and couldn't find a > > specific > > solution, in my tests on hardware this works, though. > > > > Open to suggestions. > > > > Thanks, > > Moritz > > > > --- > > drivers/net/ethernet/dec/tulip/de2104x.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/net/ethernet/dec/tulip/de2104x.c > > b/drivers/net/ethernet/dec/tulip/de2104x.c > > index f1a2da15dd0a..372c62c7e60f 100644 > > --- a/drivers/net/ethernet/dec/tulip/de2104x.c > > +++ b/drivers/net/ethernet/dec/tulip/de2104x.c > > @@ -2185,6 +2185,7 @@ static struct pci_driver de_driver = { > > .id_table = de_pci_tbl, > > .probe = de_init_one, > > .remove = de_remove_one, > > + .shutdown = de_remove_one, > > This doesn't look right: shutdown is supposed to turn off the device > without disturbing the tree or causing any knock on effects (I think > that rule is mostly because you don't want anything in userspace > triggering since it's likely to be nearly dead). Remove removes the > device from the tree and cleans up everything. I think the function > you want that's closest to what shutdown needs is de_close(). That > basically just turns off the chip and frees the interrupt ... you'll > have to wrapper it to call it from the pci_driver, though. Thanks for the suggestion, I like that better. I'll send a v2 after testing. I think anything that hits on de_stop_hw() will keep the NIC from fetching further descriptors. Cheers, Moritz
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