[PATCH 3/5] PCI/ERR: Notify drivers on failure to recover

[Lukas Wunner]

According to Documentation/PCI/pci-error-recovery.rst, the following shall
occur on failure to recover from a PCIe Uncorrectable Error:

  STEP 6: Permanent Failure
  -------------------------
  A "permanent failure" has occurred, and the platform cannot recover
  the device.  The platform will call error_detected() with a
  pci_channel_state_t value of pci_channel_io_perm_failure.

  The device driver should, at this point, assume the worst. It should
  cancel all pending I/O, refuse all new I/O, returning -EIO to
  higher layers. The device driver should then clean up all of its
  memory and remove itself from kernel operations, much as it would
  during system shutdown.

Sathya notes that AER does not call error_detected() on failure and thus
deviates from the document (as well as EEH, for which the document was
originally added).

Most drivers do nothing on permanent failure, but the SCSI drivers and a
number of Ethernet drivers do take advantage of the notification to flush
queues and give up resources.

Amend AER to notify such drivers and align with the documentation and EEH.

Link: https://lore.kernel.org/r/f496fc0f-64d7-46a4-8562-dba74e31a956@linux.intel.com/
Suggested-by: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy at linux.intel.com>
Signed-off-by: Lukas Wunner <lukas at wunner.de>
---
 drivers/pci/pcie/err.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index 21d554359fb1..930bb60fb761 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -110,7 +110,19 @@ static int report_normal_detected(struct pci_dev *dev, void *data)
 
 static int report_perm_failure_detected(struct pci_dev *dev, void *data)
 {
+	struct pci_driver *pdrv;
+	const struct pci_error_handlers *err_handler;
+
+	device_lock(&dev->dev);
+	pdrv = dev->driver;
+	if (!pdrv || !pdrv->err_handler || !pdrv->err_handler->error_detected)
+		goto out;
+
+	err_handler = pdrv->err_handler;
+	err_handler->error_detected(dev, pci_channel_io_perm_failure);
+out:
 	pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
+	device_unlock(&dev->dev);
 	return 0;
 }
 
-- 
2.47.2