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>

1 files changed, 20 insertions, 13 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 97061928249a..f6785bced215 100644
--- 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