Re: [PATCH v9 09/15] PCI/ERR: Add pci_walk_bridge() to pcie_do_recovery()

Bjorn Helgaas
2020-10-16T17:19:35Z

On Thu, Oct 15, 2020 at 05:11:07PM -0700, Sean V Kelley wrote:
> From: Sean V Kelley <sean.v.kelley@intel.com>
>
> Consolidate subordinate bus checks with pci_walk_bus() into
> pci_walk_bridge() for walking below potentially AER affected bridges.
>
> [bhelgaas: fix kerneldoc]
> Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
> Link: https://lore.kernel.org/r/20201002184735.1229220-7-seanvk.dev@oregontracks.org
> Signed-off-by: Sean V Kelley <sean.v.kelley@intel.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> drivers/pci/pcie/err.c | 30 +++++++++++++++++++++++-------
> 1 file changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> index 931e75f2549d..8b53aecdb43d 100644
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -146,13 +146,30 @@ static int report_resume(struct pci_dev *dev, void *data)
> return 0;
> }
>
> +/**
> + * pci_walk_bridge - walk bridges potentially AER affected
> + * @bridge: bridge which may be a Port
> + * @cb: callback to be called for each device found
> + * @userdata: arbitrary pointer to be passed to callback
> + *
> + * If the device provided is a bridge, walk the subordinate bus, including
> + * any bridged devices on buses under this bus. Call the provided callback
> + * on each device found.
> + */
> +static void pci_walk_bridge(struct pci_dev *bridge,
> + int (*cb)(struct pci_dev *, void *),
> + void *userdata)
> +{
> + if (bridge->subordinate)

Remind me why we add this bridge->subordinate test? I see that we're
going to need it later, but I think we should add the test in the same
patch that adds the case where "bridge->subordinate == NULL" becomes
possible.

Or else a note in this commit log about what's happening.

AFAICT, this test is literally the only possible functional change in
this patch, so the commit log should mention it.

> + pci_walk_bus(bridge->subordinate, cb, userdata);
> +}
> +
> pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> pci_channel_state_t state,
> pci_ers_result_t (*reset_subordinates)(struct pci_dev *pdev))
> {
> int type = pci_pcie_type(dev);
> struct pci_dev *bridge;
> - struct pci_bus *bus;
> pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
>
> /*
> @@ -165,23 +182,22 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> else
> bridge = pci_upstream_bridge(dev);
>
> - bus = bridge->subordinate;
> pci_dbg(bridge, "broadcast error_detected message\n");
> if (state == pci_channel_io_frozen) {
> - pci_walk_bus(bus, report_frozen_detected, &status);
> + pci_walk_bridge(bridge, report_frozen_detected, &status);
> status = reset_subordinates(bridge);
> if (status != PCI_ERS_RESULT_RECOVERED) {
> pci_warn(bridge, "subordinate device reset failed\n");
> goto failed;
> }
> } else {
> - pci_walk_bus(bus, report_normal_detected, &status);
> + pci_walk_bridge(bridge, report_normal_detected, &status);
> }
>
> if (status == PCI_ERS_RESULT_CAN_RECOVER) {
> status = PCI_ERS_RESULT_RECOVERED;
> pci_dbg(bridge, "broadcast mmio_enabled message\n");
> - pci_walk_bus(bus, report_mmio_enabled, &status);
> + pci_walk_bridge(bridge, report_mmio_enabled, &status);
> }
>
> if (status == PCI_ERS_RESULT_NEED_RESET) {
> @@ -192,14 +208,14 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> */
> status = PCI_ERS_RESULT_RECOVERED;
> pci_dbg(bridge, "broadcast slot_reset message\n");
> - pci_walk_bus(bus, report_slot_reset, &status);
> + pci_walk_bridge(bridge, report_slot_reset, &status);
> }
>
> if (status != PCI_ERS_RESULT_RECOVERED)
> goto failed;
>
> pci_dbg(bridge, "broadcast resume message\n");
> - pci_walk_bus(bus, report_resume, &status);
> + pci_walk_bridge(bridge, report_resume, &status);
>
> if (pcie_aer_is_native(bridge))
> pcie_clear_device_status(bridge);
> --
> 2.28.0
>