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Commit b7c1fadd authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

ACPI: Do not use krefs under a mutex in osl.c 



The reference counting of ACPI iomaps is carried out entirely under
acpi_ioremap_lock, so it is sufficient to use simple counters instead
of krefs for this purpose.

Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent 7ffd0443

drivers/acpi/osl.c

+16 −20
Original line number Diff line number Diff line
@@ -105,7 +105,7 @@ struct acpi_ioremap { 
	void __iomem *virt;

	acpi_physical_address phys;

	acpi_size size;

	struct kref ref;

	unsigned long refcount;

};



static LIST_HEAD(acpi_ioremaps);
@@ -319,7 +319,7 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size) 
	/* Check if there's a suitable mapping already. */

	map = acpi_map_lookup(phys, size);

	if (map) {

		kref_get(&map->ref);

		map->refcount++;

		goto out;

	}
@@ -342,7 +342,7 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size) 
	map->virt = virt;

	map->phys = pg_off;

	map->size = pg_sz;

	kref_init(&map->ref);

	map->refcount = 1;



	list_add_tail_rcu(&map->list, &acpi_ioremaps);
@@ -352,25 +352,24 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size) 
}

EXPORT_SYMBOL_GPL(acpi_os_map_memory);



static void acpi_kref_del_iomap(struct kref *ref)

static void acpi_os_drop_map_ref(struct acpi_ioremap *map)

{

	struct acpi_ioremap *map;



	map = container_of(ref, struct acpi_ioremap, ref);

	if (!--map->refcount)

		list_del_rcu(&map->list);

}



static void acpi_os_remove_map(struct acpi_ioremap *map)

static void acpi_os_map_cleanup(struct acpi_ioremap *map)

{

	if (!map->refcount) {

		synchronize_rcu();

		iounmap(map->virt);

		kfree(map);

	}

}



void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)

{

	struct acpi_ioremap *map;

	int del;



	if (!acpi_gbl_permanent_mmap) {

		__acpi_unmap_table(virt, size);
@@ -384,11 +383,10 @@ void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size) 
		WARN(true, PREFIX "%s: bad address %p\n", __func__, virt);

		return;

	}

	del = kref_put(&map->ref, acpi_kref_del_iomap);

	acpi_os_drop_map_ref(map);

	mutex_unlock(&acpi_ioremap_lock);



	if (del)

		acpi_os_remove_map(map);

	acpi_os_map_cleanup(map);

}

EXPORT_SYMBOL_GPL(acpi_os_unmap_memory);
@@ -418,7 +416,6 @@ static int acpi_os_map_generic_address(struct acpi_generic_address *addr) 
static void acpi_os_unmap_generic_address(struct acpi_generic_address *addr)

{

	struct acpi_ioremap *map;

	int del;



	if (addr->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)

		return;
@@ -432,11 +429,10 @@ static void acpi_os_unmap_generic_address(struct acpi_generic_address *addr) 
		mutex_unlock(&acpi_ioremap_lock);

		return;

	}

	del = kref_put(&map->ref, acpi_kref_del_iomap);

	acpi_os_drop_map_ref(map);

	mutex_unlock(&acpi_ioremap_lock);



	if (del)

		acpi_os_remove_map(map);

	acpi_os_map_cleanup(map);

}



#ifdef ACPI_FUTURE_USAGE