On 4/29/20 5:42 PM, Jay Vosburgh wrote:
Commit 6d2c89441571 ("PCI/ERR: Update error status after
reset_link()"), introduced a regression, as pcie_do_recovery will
discard 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 initating 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.
I think this issue is related to the issue discussed in following
thread (DPC non-hotplug support).
https://lkml.org/lkml/2020/3/28/328
If my assumption is correct, you are dealing with devices which are
not hotplug capable. If the devices are hotplug capable then you don't
need to proceed to report_slot_reset(), since hotplug handler will
remove/re-enumerate the devices correctly.
Inspection shows a similar path is plausible for a return of
_CAN_RECOVER and the invocation of report_mmio_enabled.
Resolve this by preserving the result of report_frozen_detected if
reset_link does not return _DISCONNECT.
Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
Signed-off-by: Jay Vosburgh <jay.vosburgh@xxxxxxxxxxxxx>
---
drivers/pci/pcie/err.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index 14bb8f54723e..e4274562f3a0 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -164,10 +164,17 @@ 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_ers_result_t status2;
+
pci_walk_bus(bus, report_frozen_detected, &status);
- status = reset_link(dev);
- if (status != PCI_ERS_RESULT_RECOVERED) {
+ /* preserve status from report_frozen_detected to
+ * insure report_mmio_enabled or report_slot_reset are
+ * invoked even if reset_link returns _RECOVERED.
+ */
+ status2 = reset_link(dev);
+ if (status2 != PCI_ERS_RESULT_RECOVERED) {
pci_warn(dev, "link reset failed\n");
+ status = status2;
goto failed;
}
} else {
