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Subject[PATCH 6/11] ACPI: Avoid walking the list of iomaps in osl.c twice in a row
Date
From: Rafael J. Wysocki <rjw@sisk.pl>

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>
---
drivers/acpi/osl.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)
Index: linux-2.6/drivers/acpi/osl.c
===================================================================
--- linux-2.6.orig/drivers/acpi/osl.c
+++ linux-2.6/drivers/acpi/osl.c
@@ -358,6 +358,13 @@ static void acpi_kref_del_iomap(struct k
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 __i
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(s

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_addres
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


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