ACPI: Avoid walking the list of memory mappings in osl.c twice in a row

Make acpi_os_unmap_generic_address() use acpi_map_lookup() to find
the desired iomap and drop the reference to it directly (and
eventually remove it if necessary) instead of calling
acpi_os_unmap_memory(), which requires us to walk the list of ACPI
iomaps twice in a row (first, to get the virtual address associated
with the iomap and second, to get the iomap itself).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 9706192..f6785bc 100644 (file)
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -358,6 +358,13 @@ static void acpi_kref_del_iomap(struct kref *ref)
        list_del_rcu(&map->list);
 }
 
+static void acpi_os_remove_map(struct acpi_ioremap *map)
+{
+       synchronize_rcu();
+       iounmap(map->virt);
+       kfree(map);
+}
+
 void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
 {
        struct acpi_ioremap *map;
@@ -372,20 +379,14 @@ void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
        map = acpi_map_lookup_virt(virt, size);
        if (!map) {
                mutex_unlock(&acpi_ioremap_lock);
-               printk(KERN_ERR PREFIX "%s: bad address %p\n", __func__, virt);
-               dump_stack();
+               WARN(true, PREFIX "%s: bad address %p\n", __func__, virt);
                return;
        }
-
        del = kref_put(&map->ref, acpi_kref_del_iomap);
        mutex_unlock(&acpi_ioremap_lock);
 
-       if (!del)
-               return;
-
-       synchronize_rcu();
-       iounmap(map->virt);
-       kfree(map);
+       if (del)
+               acpi_os_remove_map(map);
 }
 EXPORT_SYMBOL_GPL(acpi_os_unmap_memory);
 
@@ -414,8 +415,8 @@ static int acpi_os_map_generic_address(struct acpi_generic_address *addr)
 
 static void acpi_os_unmap_generic_address(struct acpi_generic_address *addr)
 {
-       void __iomem *virt;
-       acpi_size size = addr->bit_width / 8;
+       struct acpi_ioremap *map;
+       int del;
 
        if (addr->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
                return;
@@ -424,10 +425,16 @@ static void acpi_os_unmap_generic_address(struct acpi_generic_address *addr)
                return;
 
        mutex_lock(&acpi_ioremap_lock);
-       virt = acpi_map_vaddr_lookup(addr->address, size);
+       map = acpi_map_lookup(addr->address, addr->bit_width / 8);
+       if (!map) {
+               mutex_unlock(&acpi_ioremap_lock);
+               return;
+       }
+       del = kref_put(&map->ref, acpi_kref_del_iomap);
        mutex_unlock(&acpi_ioremap_lock);
 
-       acpi_os_unmap_memory(virt, size);
+       if (del)
+               acpi_os_remove_map(map);
 }
 
 #ifdef ACPI_FUTURE_USAGE