PCI: Keep original resource if we fail to expand it

If we have space assigned to a resource, we try to expand the resource
(e.g., to accommodate SR-IOV resources), and the expansion attempt fails,
we should keep the original assignment.

After bd064f0a231a ("PCI: Mark resources as IORESOURCE_UNSET if we can't
assign them"), we left the resource marked IORESOURCE_UNSET when the
expansion failed, even if it had originally been set.  That caused errors
like this:

  pci 0003:00:00.0: can't enable device: BAR 15 [mem size 0x0c000000 64bit pref] not assigned
  pci 0003:00:00.0: Error enabling bridge (-22), continuing

Fix this by restoring the original flags when reassignment fails.

[bhelgaas: reworked to simplify, changelog]
Fixes: bd064f0a231a ("PCI: Mark resources as IORESOURCE_UNSET if we can't assign them")
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v3.15+

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index caed1ce6facd..481c4e18693a 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -320,9 +320,11 @@ int pci_reassign_resource(struct pci_dev *dev, int resno, resource_size_t addsiz
                         resource_size_t min_align)
 {
         struct resource *res = dev->resource + resno;
+        unsigned long flags;
         resource_size_t new_size;
         int ret;
 
+        flags = res->flags;
         res->flags |= IORESOURCE_UNSET;
         if (!res->parent) {
                 dev_info(&dev->dev, "BAR %d: can't reassign an unassigned resource %pR\n",
@@ -339,7 +341,12 @@ int pci_reassign_resource(struct pci_dev *dev, int resno, resource_size_t addsiz
                 dev_info(&dev->dev, "BAR %d: reassigned %pR\n", resno, res);
                 if (resno < PCI_BRIDGE_RESOURCES)
                         pci_update_resource(dev, resno);
+        } else {
+                res->flags = flags;
+                dev_info(&dev->dev, "BAR %d: %pR (failed to expand by %#llx)\n",
+                         resno, res, (unsigned long long) addsize);
         }
+
         return ret;
 }