Messages in this thread | | | Subject | Re: [PATCH v11 1/8] PCI/ERR: Update error status after reset_link() | From | Kuppuswamy Sathyanarayanan <> | Date | Thu, 9 Jan 2020 17:08:15 -0800 |
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On 1/9/20 3:26 PM, Bjorn Helgaas wrote: > On Wed, Jan 08, 2020 at 04:14:09PM -0800, Kuppuswamy Sathyanarayanan wrote: >> On 1/3/20 6:54 PM, Bjorn Helgaas wrote: >>> On Fri, Jan 03, 2020 at 05:03:03PM -0800, Kuppuswamy Sathyanarayanan wrote: >>>> On 1/3/20 4:34 PM, Bjorn Helgaas wrote: >>>>> On Thu, Dec 26, 2019 at 04:39:07PM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote: >>>>>> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> >>>>>> >>>>>> Commit bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") uses >>>>>> reset_link() to recover from fatal errors. But, if the reset is >>>>>> successful there is no need to continue the rest of the error recovery >>>>>> checks. Also, during fatal error recovery, if the initial value of error >>>>>> status is PCI_ERS_RESULT_DISCONNECT or PCI_ERS_RESULT_NO_AER_DRIVER then >>>>>> even after successful recovery (using reset_link()) pcie_do_recovery() >>>>>> will report the recovery result as failure. So update the status of >>>>>> error after reset_link(). >>>>> I like the part about updating "status" with the result of >>>>> reset_link(), and I split that into its own patch because it >>>>> seems like a fix that *can* be separated. >>>>> >>>>> But I'm not convinced that we should skip the ->slot_reset() >>>>> callbacks if the reset_link() was successful. >>>> If reset_link() call is successful then the result value will be >>>> "PCI_ERS_RESULT_RECOVERED". So even if you proceed with >>>> rest of the code, slot_reset() will never get called right ? >>> The current code: >>> >>> if (state == pci_channel_io_frozen && >>> reset_link(dev, service) != PCI_ERS_RESULT_RECOVERED) >>> goto failed; >>> ... >>> if (status == PCI_ERS_RESULT_NEED_RESET) { >>> status = PCI_ERS_RESULT_RECOVERED; >>> pci_walk_bus(bus, report_slot_reset, &status); >>> >>> doesn't save the result of reset_link(), so if status was >>> PCI_ERS_RESULT_NEED_RESET and the reset succeeds, we will call >>> ->slot_reset(). >>> >>> After your patch, if "state == pci_channel_io_frozen", we *never* call >>> ->slot_reset(). >>> >>> Do you think that matches pci-error-recovery.rst? It doesn't seem >>> like it to me, but perhaps I haven't read it closely enough. >> Documentation does not have clear details on what to do with return >> value of reset_link() (step 3). But IMO, if step 3 recovers the device and >> returns PCI_ERS_RESULT_RECOVERED then there is no need to proceed >> to slot reset (step 4). May be we should update the Documentation? > Are you suggesting we don't need to call a driver callback after > resetting the device? Note that the ->slot_reset() doesn't *perform* > a reset; it is called *after* completion of a reset. > > The doc says: > > ... Upon completion of slot reset, the platform will call the device > slot_reset() callback. > ... > This call gives drivers the chance to re-initialize the hardware > (re-download firmware, etc.). At this point, the driver may assume > that the card is in a fresh state and is fully functional. The slot > is unfrozen and the driver has full access to PCI config space, > memory mapped I/O space and DMA. Interrupts (Legacy, MSI, or MSI-X) > will also be available. Got it. Let me fix it in next version. But, will this sequence apply for fatal error recovery (triggered from DPC code path) ? I think the device is removed and re-added in hotplug path (DLLSC transition). > > After we reset a device, the driver certainly needs a chance to > reinitialize it. > >>>>> According to >>>>> Documentation/PCI/pci-error-recovery.rst, we should call >>>>> ->slot_reset() after completion of the reset. >>>>> >>>>> For example, rsxx_err_handler implements ->slot_reset(), but >>>>> not ->resume(). If we reset the device, we'll claim success and >>>>> return, but we won't call rsxx_slot_reset(), which does a bunch >>>>> of important-looking recovery stuff. >>>>> >>>>> If pci-error-recovery.rst is wrong, we should fix that (after >>>>> auditing all the drivers to make sure they match). >>>>> >>>>>> Fixes: bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") >>>>>> Cc: Ashok Raj <ashok.raj@intel.com> >>>>>> Cc: Keith Busch <keith.busch@intel.com> >>>>>> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> >>>>>> Acked-by: Keith Busch <keith.busch@intel.com> >>>>>> --- >>>>>> drivers/pci/pcie/err.c | 10 +++++++--- >>>>>> 1 file changed, 7 insertions(+), 3 deletions(-) >>>>>> >>>>>> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c >>>>>> index b0e6048a9208..53cd9200ec2c 100644 >>>>>> --- a/drivers/pci/pcie/err.c >>>>>> +++ b/drivers/pci/pcie/err.c >>>>>> @@ -204,9 +204,12 @@ void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state, >>>>>> else >>>>>> pci_walk_bus(bus, report_normal_detected, &status); >>>>>> - if (state == pci_channel_io_frozen && >>>>>> - reset_link(dev, service) != PCI_ERS_RESULT_RECOVERED) >>>>>> - goto failed; >>>>>> + if (state == pci_channel_io_frozen) { >>>>>> + status = reset_link(dev, service); >>>>>> + if (status != PCI_ERS_RESULT_RECOVERED) >>>>>> + goto failed; >>>>>> + goto done; >>>>>> + } >>>>>> if (status == PCI_ERS_RESULT_CAN_RECOVER) { >>>>>> status = PCI_ERS_RESULT_RECOVERED; >>>>>> @@ -228,6 +231,7 @@ void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state, >>>>>> if (status != PCI_ERS_RESULT_RECOVERED) >>>>>> goto failed; >>>>>> +done: >>>>>> pci_dbg(dev, "broadcast resume message\n"); >>>>>> pci_walk_bus(bus, report_resume, &status); >>>>>> -- >>>>>> 2.21.0 >>>>>> >>>> -- >>>> Sathyanarayanan Kuppuswamy >>>> Linux kernel developer >>>> >> -- >> Sathyanarayanan Kuppuswamy >> Linux kernel developer >> -- Sathyanarayanan Kuppuswamy Linux kernel developer
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