Merge branch 'pci/msi' into next

* pci/msi:
  PCI/MSI: Remove unnecessary temporary variable
  PCI/MSI: Use __write_msi_msg() instead of write_msi_msg()
  MSI/powerpc: Use __read_msi_msg() instead of read_msi_msg()
  PCI/MSI: Use __get_cached_msi_msg() instead of get_cached_msi_msg()
  PCI/MSI: Add "msi_bus" sysfs MSI/MSI-X control for endpoints
  PCI/MSI: Remove "pos" from the struct msi_desc msi_attrib
  PCI/MSI: Remove unused kobject from struct msi_desc
  PCI/MSI: Rename pci_msi_check_device() to pci_msi_supported()
  PCI/MSI: Move D0 check into pci_msi_check_device()
  PCI/MSI: Remove arch_msi_check_device()
  irqchip: armada-370-xp: Remove arch_msi_check_device()
  PCI/MSI/PPC: Remove arch_msi_check_device()

Conflicts:
	drivers/pci/host/pcie-designware.c

1 files changed, 19 insertions, 20 deletions

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 76ef7914c9aa..92b6d9ab00e4 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -250,46 +250,45 @@ static ssize_t msi_bus_show(struct device *dev, struct device_attribute *attr,
                             char *buf)
 {
         struct pci_dev *pdev = to_pci_dev(dev);
+        struct pci_bus *subordinate = pdev->subordinate;
 
-        if (!pdev->subordinate)
-                return 0;
-
-        return sprintf(buf, "%u\n",
-                       !(pdev->subordinate->bus_flags & PCI_BUS_FLAGS_NO_MSI));
+        return sprintf(buf, "%u\n", subordinate ?
+                       !(subordinate->bus_flags & PCI_BUS_FLAGS_NO_MSI)
+                           : !pdev->no_msi);
 }
 
 static ssize_t msi_bus_store(struct device *dev, struct device_attribute *attr,
                              const char *buf, size_t count)
 {
         struct pci_dev *pdev = to_pci_dev(dev);
+        struct pci_bus *subordinate = pdev->subordinate;
         unsigned long val;
 
         if (kstrtoul(buf, 0, &val) < 0)
                 return -EINVAL;
 
-        /*
-         * Bad things may happen if the no_msi flag is changed
-         * while drivers are loaded.
-         */
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
         /*
-         * Maybe devices without subordinate buses shouldn't have this
-         * attribute in the first place?
+         * "no_msi" and "bus_flags" only affect what happens when a driver
+         * requests MSI or MSI-X.  They don't affect any drivers that have
+         * already requested MSI or MSI-X.
          */
-        if (!pdev->subordinate)
+        if (!subordinate) {
+                pdev->no_msi = !val;
+                dev_info(&pdev->dev, "MSI/MSI-X %s for future drivers\n",
+                         val ? "allowed" : "disallowed");
                 return count;
-
-        /* Is the flag going to change, or keep the value it already had? */
-        if (!(pdev->subordinate->bus_flags & PCI_BUS_FLAGS_NO_MSI) ^
-            !!val) {
-                pdev->subordinate->bus_flags ^= PCI_BUS_FLAGS_NO_MSI;
-
-                dev_warn(&pdev->dev, "forced subordinate bus to%s support MSI, bad things could happen\n",
-                         val ? "" : " not");
         }
 
+        if (val)
+                subordinate->bus_flags &= ~PCI_BUS_FLAGS_NO_MSI;
+        else
+                subordinate->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
+
+        dev_info(&subordinate->dev, "MSI/MSI-X %s for future drivers of devices on this bus\n",
+                 val ? "allowed" : "disallowed");
         return count;
 }
 static DEVICE_ATTR_RW(msi_bus);