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    SubjectRe: [PATCH v1 1/1] PCI/ERR: Handle fatal error recovery for non-hotplug capable devices
    Date
    sathyanarayanan.kuppuswamy@linux.intel.com wrote:

    >From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
    >
    >If there are non-hotplug capable devices connected to a given
    >port, then during the fatal error recovery(triggered by DPC or
    >AER), after calling reset_link() function, we cannot rely on
    >hotplug handler to detach and re-enumerate the device drivers
    >in the affected bus. Instead, we will have to let the error
    >recovery handler call report_slot_reset() for all devices in
    >the bus to notify about the reset operation. Although this is
    >only required for non hot-plug capable devices, doing it for
    >hotplug capable devices should not affect the functionality.

    Yicong,

    Does the patch below also resolve the issue for you, as with
    your changed version of my original patch?

    -J

    >Along with above issue, this fix also applicable to following
    >issue.
    >
    >Commit 6d2c89441571 ("PCI/ERR: Update error status after
    >reset_link()") added support to store status of reset_link()
    >call. Although this fixed the error recovery issue observed if
    >the initial value of error status is PCI_ERS_RESULT_DISCONNECT
    >or PCI_ERS_RESULT_NO_AER_DRIVER, it also discarded the status
    >result from report_frozen_detected. This can cause a failure to
    >recover if _NEED_RESET is returned by report_frozen_detected and
    >report_slot_reset is not invoked.
    >
    >Such an event can be induced for testing purposes by reducing the
    >Max_Payload_Size of a PCIe bridge to less than that of a device
    >downstream from the bridge, and then initiating I/O through the
    >device, resulting in oversize transactions. In the presence of DPC,
    >this results in a containment event and attempted reset and recovery
    >via pcie_do_recovery. After 6d2c89441571 report_slot_reset is not
    >invoked, and the device does not recover.
    >
    >[original patch is from jay.vosburgh@canonical.com]
    >[original patch link https://lore.kernel.org/linux-pci/18609.1588812972@famine/]
    >Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
    >Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
    >Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
    >---
    > drivers/pci/pcie/err.c | 19 +++++++++++++++----
    > 1 file changed, 15 insertions(+), 4 deletions(-)
    >
    >diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
    >index 14bb8f54723e..db80e1ecb2dc 100644
    >--- a/drivers/pci/pcie/err.c
    >+++ b/drivers/pci/pcie/err.c
    >@@ -165,13 +165,24 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
    > pci_dbg(dev, "broadcast error_detected message\n");
    > if (state == pci_channel_io_frozen) {
    > pci_walk_bus(bus, report_frozen_detected, &status);
    >- status = reset_link(dev);
    >- if (status != PCI_ERS_RESULT_RECOVERED) {
    >+ status = PCI_ERS_RESULT_NEED_RESET;
    >+ } else {
    >+ pci_walk_bus(bus, report_normal_detected, &status);
    >+ }
    >+
    >+ if (status == PCI_ERS_RESULT_NEED_RESET) {
    >+ if (reset_link) {
    >+ if (reset_link(dev) != PCI_ERS_RESULT_RECOVERED)
    >+ status = PCI_ERS_RESULT_DISCONNECT;
    >+ } else {
    >+ if (pci_bus_error_reset(dev))
    >+ status = PCI_ERS_RESULT_DISCONNECT;
    >+ }
    >+
    >+ if (status == PCI_ERS_RESULT_DISCONNECT) {
    > pci_warn(dev, "link reset failed\n");
    > goto failed;
    > }
    >- } else {
    >- pci_walk_bus(bus, report_normal_detected, &status);
    > }
    >
    > if (status == PCI_ERS_RESULT_CAN_RECOVER) {
    >--
    >2.17.1
    >

    ---
    -Jay Vosburgh, jay.vosburgh@canonical.com

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