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 68a921d..41c5e1b 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).