PCI/ACPI: Don't cache _PRT, and don't associate them with bus numbers

Previously, we cached _PRT (PCI routing table, ACPI 5.0 sec 6.2.12)
contents and associated each _PRT entry with a PCI bus number.  The bus
number association means dependencies on PCI device enumeration and bus
number assignment, as well as on the PCI/ACPI binding process.

After 4f535093cf ("PCI: Put pci_dev in device tree as early as possible"),
these dependencies caused the IRQ issues reported by Peter:

    pci 0000:00:1e.0: PCI bridge to [bus 09] (subtractive decode)
    pci 0000:00:1e.0: can't derive routing for PCI INT A
    snd_ctxfi 0000:09:02.0: PCI INT A: no GSI - using ISA IRQ 5
    irq 18: nobody cared (try booting with the "irqpoll" option)

This patch removes _PRT caching.  Instead, we evaluate _PRT as needed
in the pci_enable_device() path.  This also removes the dependency on
PCI bus numbers: we can simply look at the _PRT associated with each
bridge as we walk upstream toward the root.

[bhelgaas: changelog]
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=53561
Reported-and-tested-by: Peter Hurley <peter@hurleysoftware.com>
Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 34 insertions, 68 deletions

diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index 68a921d03247..41c5e1b799ef 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -53,9 +53,6 @@ struct acpi_prt_entry {
         u32                     index;          /* GSI, or link _CRS index */
 };
 
-static LIST_HEAD(acpi_prt_list);
-static DEFINE_SPINLOCK(acpi_prt_lock);
-
 static inline char pin_name(int pin)
 {
         return 'A' + pin - 1;
@@ -65,28 +62,6 @@ static inline char pin_name(int pin)
                          PCI IRQ Routing Table (PRT) Support
    -------------------------------------------------------------------------- */
 
-static struct acpi_prt_entry *acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
-                                                          int pin)
-{
-        struct acpi_prt_entry *entry;
-        int segment = pci_domain_nr(dev->bus);
-        int bus = dev->bus->number;
-        int device = PCI_SLOT(dev->devfn);
-
-        spin_lock(&acpi_prt_lock);
-        list_for_each_entry(entry, &acpi_prt_list, list) {
-                if ((segment == entry->id.segment)
-                    && (bus == entry->id.bus)
-                    && (device == entry->id.device)
-                    && (pin == entry->pin)) {
-                        spin_unlock(&acpi_prt_lock);
-                        return entry;
-                }
-        }
-        spin_unlock(&acpi_prt_lock);
-        return NULL;
-}
-
 /* http://bugzilla.kernel.org/show_bug.cgi?id=4773 */
 static const struct dmi_system_id medion_md9580[] = {
         {
@@ -184,11 +159,19 @@ static void do_prt_fixups(struct acpi_prt_entry *entry,
         }
 }
 
-static int acpi_pci_irq_add_entry(acpi_handle handle, int segment, int bus,
-                                  struct acpi_pci_routing_table *prt)
+static int acpi_pci_irq_check_entry(acpi_handle handle, struct pci_dev *dev,
+                                  int pin, struct acpi_pci_routing_table *prt,
+                                  struct acpi_prt_entry **entry_ptr)
 {
+        int segment = pci_domain_nr(dev->bus);
+        int bus = dev->bus->number;
+        int device = PCI_SLOT(dev->devfn);
         struct acpi_prt_entry *entry;
 
+        if (((prt->address >> 16) & 0xffff) != device ||
+            prt->pin + 1 != pin)
+                return -ENODEV;
+
         entry = kzalloc(sizeof(struct acpi_prt_entry), GFP_KERNEL);
         if (!entry)
                 return -ENOMEM;
@@ -237,43 +220,37 @@ static int acpi_pci_irq_add_entry(acpi_handle handle, int segment, int bus,
                               entry->id.device, pin_name(entry->pin),
                               prt->source, entry->index));
 
-        spin_lock(&acpi_prt_lock);
-        list_add_tail(&entry->list, &acpi_prt_list);
-        spin_unlock(&acpi_prt_lock);
+        *entry_ptr = entry;
 
         return 0;
 }
 
-int acpi_pci_irq_add_prt(acpi_handle handle, int segment, int bus)
+static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
+                          int pin, struct acpi_prt_entry **entry_ptr)
 {
         acpi_status status;
         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
         struct acpi_pci_routing_table *entry;
+        acpi_handle handle = NULL;
 
-        /* 'handle' is the _PRT's parent (root bridge or PCI-PCI bridge) */
-        status = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
-        if (ACPI_FAILURE(status))
-                return -ENODEV;
-
-        printk(KERN_DEBUG "ACPI: PCI Interrupt Routing Table [%s._PRT]\n",
-               (char *) buffer.pointer);
-
-        kfree(buffer.pointer);
+        if (dev->bus->bridge)
+                handle = ACPI_HANDLE(dev->bus->bridge);
 
-        buffer.length = ACPI_ALLOCATE_BUFFER;
-        buffer.pointer = NULL;
+        if (!handle)
+                return -ENODEV;
 
+        /* 'handle' is the _PRT's parent (root bridge or PCI-PCI bridge) */
         status = acpi_get_irq_routing_table(handle, &buffer);
         if (ACPI_FAILURE(status)) {
-                ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PRT [%s]",
-                                acpi_format_exception(status)));
                 kfree(buffer.pointer);
                 return -ENODEV;
         }
 
         entry = buffer.pointer;
         while (entry && (entry->length > 0)) {
-                acpi_pci_irq_add_entry(handle, segment, bus, entry);
+                if (!acpi_pci_irq_check_entry(handle, dev, pin,
+                                                 entry, entry_ptr))
+                        break;
                 entry = (struct acpi_pci_routing_table *)
                     ((unsigned long)entry + entry->length);
         }
@@ -282,23 +259,6 @@ int acpi_pci_irq_add_prt(acpi_handle handle, int segment, int bus)
         return 0;
 }
 
-void acpi_pci_irq_del_prt(int segment, int bus)
-{
-        struct acpi_prt_entry *entry, *tmp;
-
-        printk(KERN_DEBUG
-               "ACPI: Delete PCI Interrupt Routing Table for %04x:%02x\n",
-               segment, bus);
-        spin_lock(&acpi_prt_lock);
-        list_for_each_entry_safe(entry, tmp, &acpi_prt_list, list) {
-                if (segment == entry->id.segment && bus == entry->id.bus) {
-                        list_del(&entry->list);
-                        kfree(entry);
-                }
-        }
-        spin_unlock(&acpi_prt_lock);
-}
-
 /* --------------------------------------------------------------------------
                           PCI Interrupt Routing Support
    -------------------------------------------------------------------------- */
@@ -359,12 +319,13 @@ static int acpi_reroute_boot_interrupt(struct pci_dev *dev,
 
 static struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin)
 {
-        struct acpi_prt_entry *entry;
+        struct acpi_prt_entry *entry = NULL;
         struct pci_dev *bridge;
         u8 bridge_pin, orig_pin = pin;
+        int ret;
 
-        entry = acpi_pci_irq_find_prt_entry(dev, pin);
-        if (entry) {
+        ret = acpi_pci_irq_find_prt_entry(dev, pin, &entry);
+        if (!ret && entry) {
 #ifdef CONFIG_X86_IO_APIC
                 acpi_reroute_boot_interrupt(dev, entry);
 #endif /* CONFIG_X86_IO_APIC */
@@ -373,7 +334,7 @@ static struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin)
                 return entry;
         }
 
-        /* 
+        /*
          * Attempt to derive an IRQ for this device from a parent bridge's
          * PCI interrupt routing entry (eg. yenta bridge and add-in card bridge).
          */
@@ -393,8 +354,8 @@ static struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin)
                         pin = bridge_pin;
                 }
 
-                entry = acpi_pci_irq_find_prt_entry(bridge, pin);
-                if (entry) {
+                ret = acpi_pci_irq_find_prt_entry(bridge, pin, &entry);
+                if (!ret && entry) {
                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                          "Derived GSI for %s INT %c from %s\n",
                                          pci_name(dev), pin_name(orig_pin),
@@ -470,6 +431,7 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
                         dev_warn(&dev->dev, "PCI INT %c: no GSI\n",
                                  pin_name(pin));
                 }
+
                 return 0;
         }
 
@@ -477,6 +439,7 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
         if (rc < 0) {
                 dev_warn(&dev->dev, "PCI INT %c: failed to register GSI\n",
                          pin_name(pin));
+                kfree(entry);
                 return rc;
         }
         dev->irq = rc;
@@ -491,6 +454,7 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
                 (triggering == ACPI_LEVEL_SENSITIVE) ? "level" : "edge",
                 (polarity == ACPI_ACTIVE_LOW) ? "low" : "high", dev->irq);
 
+        kfree(entry);
         return 0;
 }
 
@@ -513,6 +477,8 @@ void acpi_pci_irq_disable(struct pci_dev *dev)
         else
                 gsi = entry->index;
 
+        kfree(entry);
+
         /*
          * TBD: It might be worth clearing dev->irq by magic constant
          * (e.g. PCI_UNDEFINED_IRQ).