Messages in this thread | | | Date | Thu, 24 May 2018 09:35:57 -0400 | From | okaya@codeauro ... | Subject | Re: [PATCH V2] PCI/portdrv: do not disable device on reboot/shutdown |
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On 2018-05-24 09:07, Bjorn Helgaas wrote: > On Thu, May 24, 2018 at 07:43:05AM -0400, Sinan Kaya wrote: >> On 5/23/2018 6:57 PM, Sinan Kaya wrote: >> >> The crash seems to indicate that the hpsa device attempted a DMA after >> >> we cleared the Root Port's PCI_COMMAND_MASTER, which means >> >> hpsa_shutdown() didn't stop DMA from the device (it looks like *most* >> >> shutdown methods don't disable device DMA, so it's in good company). >> > All drivers are expected to shutdown DMA and interrupts in their shutdown() >> > routines. They can skip removing threads, data structures etc. but DMA and >> > interrupt disabling are required. This is the difference between shutdown() >> > and remove() callbacks. >> >> I found this note yesterday to see why we are not disabling the >> devices in the PCI core itself. >> >> pci_device_remove() >> >> /* >> * We would love to complain here if pci_dev->is_enabled is set, that >> * the driver should have called pci_disable_device(), but the >> * unfortunate fact is there are too many odd BIOS and bridge setups >> * that don't like drivers doing that all of the time. >> * Oh well, we can dream of sane hardware when we sleep, no matter >> how >> * horrible the crap we have to deal with is when we are awake... >> */ >> >> Ryan, can you discard the previous patch and test this one instead? >> remove() path in hpsa driver seems to call pci_disable_device() via >> >> hpsa_remove_one() >> hpsa_free_pci_init() >> >> but nothing on the shutdown path. >> >> diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c >> index 4ed3d26..3823f04 100644 >> --- a/drivers/scsi/hpsa.c >> +++ b/drivers/scsi/hpsa.c >> @@ -8651,6 +8651,7 @@ static void hpsa_shutdown(struct pci_dev *pdev) >> h->access.set_intr_mask(h, HPSA_INTR_OFF); >> hpsa_free_irqs(h); /* init_one 4 */ >> hpsa_disable_interrupt_mode(h); /* pci_init 2 */ >> + pci_disable_device(h->pdev); >> } > > I suspect this will make things "work" (if the device can't attempt > DMA, no Unsupported Request error will occur). > > But I'm concerned that the reason for the DMA might that hpsa is > transferring buffers from system memory to the hpsa device, and if we > arbitrarily terminate those transfers with pci_disable_device(), we > may leave the hpsa device in an inconsistent state, e.g., with a dirty > filesystem. > > But we really need guidance from an hpsa expert. I don't know the > filesystem/SCSI/hpsa details.
Agreed,
We can drop shutdown and use the remove callback. Remove is supposed to do a safe cleanup.
> > Bjorn
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