ACPI: PCI: simplify buffer management for evaluating _PRT

Previously, acpi_pci_irq_add_prt() did all its own buffer management.
But now that we have ACPI_ALLOCATE_BUFFER, we no longer need to do
that management.  And we don't have to call acpi_get_irq_routing_table()
twice (once to learn the size of the buffer needed, and again to
actually get the table).

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 12 insertions, 40 deletions

diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index 6c04060d063b..6a9f3ddb322e 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -243,55 +243,29 @@ acpi_pci_irq_del_entry(int segment, int bus, struct acpi_prt_entry *entry)
 
 int acpi_pci_irq_add_prt(acpi_handle handle, int segment, int bus)
 {
-        acpi_status status = AE_OK;
-        char *pathname = NULL;
-        struct acpi_buffer buffer = { 0, NULL };
-        struct acpi_pci_routing_table *prt = NULL;
-        struct acpi_pci_routing_table *entry = NULL;
+        acpi_status status;
+        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+        struct acpi_pci_routing_table *entry;
         static int first_time = 1;
 
-
-        pathname = kzalloc(ACPI_PATHNAME_MAX, GFP_KERNEL);
-        if (!pathname)
-                return -ENOMEM;
-
         if (first_time) {
                 acpi_prt.count = 0;
                 INIT_LIST_HEAD(&acpi_prt.entries);
                 first_time = 0;
         }
 
-        /* 
-         * NOTE: We're given a 'handle' to the _PRT object's parent device
-         *       (either a PCI root bridge or PCI-PCI bridge).
-         */
-
-        buffer.length = ACPI_PATHNAME_MAX;
-        buffer.pointer = pathname;
-        acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
+        /* '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",
-               pathname);
+               (char *) buffer.pointer);
 
-        /* 
-         * Evaluate this _PRT and add its entries to our global list (acpi_prt).
-         */
+        kfree(buffer.pointer);
 
-        buffer.length = 0;
+        buffer.length = ACPI_ALLOCATE_BUFFER;
         buffer.pointer = NULL;
-        kfree(pathname);
-        status = acpi_get_irq_routing_table(handle, &buffer);
-        if (status != AE_BUFFER_OVERFLOW) {
-                ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PRT [%s]",
-                                acpi_format_exception(status)));
-                return -ENODEV;
-        }
-
-        prt = kzalloc(buffer.length, GFP_KERNEL);
-        if (!prt) {
-                return -ENOMEM;
-        }
-        buffer.pointer = prt;
 
         status = acpi_get_irq_routing_table(handle, &buffer);
         if (ACPI_FAILURE(status)) {
@@ -301,16 +275,14 @@ int acpi_pci_irq_add_prt(acpi_handle handle, int segment, int bus)
                 return -ENODEV;
         }
 
-        entry = prt;
-
+        entry = buffer.pointer;
         while (entry && (entry->length > 0)) {
                 acpi_pci_irq_add_entry(handle, segment, bus, entry);
                 entry = (struct acpi_pci_routing_table *)
                     ((unsigned long)entry + entry->length);
         }
 
-        kfree(prt);
-
+        kfree(buffer.pointer);
         return 0;
 }