[ +cc dongdong as we met the issue ]
Hi,
The regression happened with our intel 82599 network adaptor. A DPC event
happened on the device, recovery returns successful but the device is
not enabled. As we only reset link, but don't call driver specific
handler(mmio enable/slot reset).
If we met an error with IO blocked, the logic should be:
1. try to reset link
2. broadcast report_frozen_detected on the bus
3. do what drivers suggest(mmio enable/slot reset)
Currently only step 1 is performed, and returns directly. I tried the
patch below and it solves the issues. The differences from Jay's one
is that it merge the return value to the status and it match the logic
I mentioned above.
Regards,
Yicong
diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index 14bb8f5..6f8870c 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -164,12 +164,12 @@ 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) {
pci_warn(dev, "link reset failed\n");
goto failed;
}
+ pci_walk_bus(bus, report_frozen_detected, &status);
} else {
pci_walk_bus(bus, report_normal_detected, &status);
}
On 2020/4/30 8:42, 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.
>
> 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 {
