powerpc/eeh: Trace PCI bus from PE

There're several types of PEs can be supported for now: PHB, Bus
and Device dependent PE. For PCI bus dependent PE, tracing the
corresponding PCI bus from PE (struct eeh_pe) would make the code
more efficient. The patch also enables the retrieval of PCI bus based
on the PCI bus dependent PE.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/eeh_pe.c b/arch/powerpc/kernel/eeh_pe.c
index 3d2dcf5afc29..c96366758acf 100644
--- a/arch/powerpc/kernel/eeh_pe.c
+++ b/arch/powerpc/kernel/eeh_pe.c
@@ -365,6 +365,17 @@ int eeh_add_to_parent_pe(struct eeh_dev *edev)
         pe->config_addr = edev->config_addr;
 
         /*
+         * While doing PE reset, we probably hot-reset the
+         * upstream bridge. However, the PCI devices including
+         * the associated EEH devices might be removed when EEH
+         * core is doing recovery. So that won't safe to retrieve
+         * the bridge through downstream EEH device. We have to
+         * trace the parent PCI bus, then the upstream bridge.
+         */
+        if (eeh_probe_mode_dev())
+                pe->bus = eeh_dev_to_pci_dev(edev)->bus;
+
+        /*
          * Put the new EEH PE into hierarchy tree. If the parent
          * can't be found, the newly created PE will be attached
          * to PHB directly. Otherwise, we have to associate the
@@ -641,12 +652,18 @@ struct pci_bus *eeh_pe_bus_get(struct eeh_pe *pe)
                 bus = pe->phb->bus;
         } else if (pe->type & EEH_PE_BUS ||
                    pe->type & EEH_PE_DEVICE) {
+                if (pe->bus) {
+                        bus = pe->bus;
+                        goto out;
+                }
+
                 edev = list_first_entry(&pe->edevs, struct eeh_dev, list);
                 pdev = eeh_dev_to_pci_dev(edev);
                 if (pdev)
                         bus = pdev->bus;
         }
 
+out:
         eeh_unlock();
 
         return bus;