1 files changed, 64 insertions, 48 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 187dff96356b..45c6ac8790d7 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -104,11 +104,11 @@ struct acpi_ioremap {
 	void __iomem *virt;
 	acpi_physical_address phys;
 	acpi_size size;
-	struct kref ref;
+	unsigned long refcount;
 };
 
 static LIST_HEAD(acpi_ioremaps);
-static DEFINE_SPINLOCK(acpi_ioremap_lock);
+static DEFINE_MUTEX(acpi_ioremap_lock);
 
 static void __init acpi_osi_setup_late(void);
 
@@ -284,6 +284,22 @@ acpi_map_vaddr_lookup(acpi_physical_address phys, unsigned int size)
 	return NULL;
 }
 
+void __iomem *acpi_os_get_iomem(acpi_physical_address phys, unsigned int size)
+{
+	struct acpi_ioremap *map;
+	void __iomem *virt = NULL;
+
+	mutex_lock(&acpi_ioremap_lock);
+	map = acpi_map_lookup(phys, size);
+	if (map) {
+		virt = map->virt + (phys - map->phys);
+		map->refcount++;
+	}
+	mutex_unlock(&acpi_ioremap_lock);
+	return virt;
+}
+EXPORT_SYMBOL_GPL(acpi_os_get_iomem);
+
 /* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */
 static struct acpi_ioremap *
 acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
@@ -301,8 +317,7 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
 void __iomem *__init_refok
 acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 {
-	struct acpi_ioremap *map, *tmp_map;
-	unsigned long flags;
+	struct acpi_ioremap *map;
 	void __iomem *virt;
 	acpi_physical_address pg_off;
 	acpi_size pg_sz;
@@ -315,14 +330,25 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 	if (!acpi_gbl_permanent_mmap)
 		return __acpi_map_table((unsigned long)phys, size);
 
+	mutex_lock(&acpi_ioremap_lock);
+	/* Check if there's a suitable mapping already. */
+	map = acpi_map_lookup(phys, size);
+	if (map) {
+		map->refcount++;
+		goto out;
+	}
+
 	map = kzalloc(sizeof(*map), GFP_KERNEL);
-	if (!map)
+	if (!map) {
+		mutex_unlock(&acpi_ioremap_lock);
 		return NULL;
+	}
 
 	pg_off = round_down(phys, PAGE_SIZE);
 	pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off;
 	virt = acpi_os_ioremap(pg_off, pg_sz);
 	if (!virt) {
+		mutex_unlock(&acpi_ioremap_lock);
 		kfree(map);
 		return NULL;
 	}
@@ -331,62 +357,51 @@ 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);
-
-	spin_lock_irqsave(&acpi_ioremap_lock, flags);
-	/* Check if page has already been mapped. */
-	tmp_map = acpi_map_lookup(phys, size);
-	if (tmp_map) {
-		kref_get(&tmp_map->ref);
-		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
-		iounmap(map->virt);
-		kfree(map);
-		return tmp_map->virt + (phys - tmp_map->phys);
-	}
+	map->refcount = 1;
+
 	list_add_tail_rcu(&map->list, &acpi_ioremaps);
-	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 
+ out:
+	mutex_unlock(&acpi_ioremap_lock);
 	return map->virt + (phys - map->phys);
 }
 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;
+	if (!--map->refcount)
+		list_del_rcu(&map->list);
+}
 
-	map = container_of(ref, struct acpi_ioremap, ref);
-	list_del_rcu(&map->list);
+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;
-	unsigned long flags;
-	int del;
 
 	if (!acpi_gbl_permanent_mmap) {
 		__acpi_unmap_table(virt, size);
 		return;
 	}
 
-	spin_lock_irqsave(&acpi_ioremap_lock, flags);
+	mutex_lock(&acpi_ioremap_lock);
 	map = acpi_map_lookup_virt(virt, size);
 	if (!map) {
-		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
-		printk(KERN_ERR PREFIX "%s: bad address %p\n", __func__, virt);
-		dump_stack();
+		mutex_unlock(&acpi_ioremap_lock);
+		WARN(true, PREFIX "%s: bad address %p\n", __func__, virt);
 		return;
 	}
+	acpi_os_drop_map_ref(map);
+	mutex_unlock(&acpi_ioremap_lock);
 
-	del = kref_put(&map->ref, acpi_kref_del_iomap);
-	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
-
-	if (!del)
-		return;
-
-	synchronize_rcu();
-	iounmap(map->virt);
-	kfree(map);
+	acpi_os_map_cleanup(map);
 }
 EXPORT_SYMBOL_GPL(acpi_os_unmap_memory);
 
@@ -396,7 +411,7 @@ void __init early_acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
 		__acpi_unmap_table(virt, size);
 }
 
-int acpi_os_map_generic_address(struct acpi_generic_address *addr)
+static int acpi_os_map_generic_address(struct acpi_generic_address *addr)
 {
 	void __iomem *virt;
 
@@ -412,13 +427,10 @@ int acpi_os_map_generic_address(struct acpi_generic_address *addr)
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(acpi_os_map_generic_address);
 
-void acpi_os_unmap_generic_address(struct acpi_generic_address *addr)
+static void acpi_os_unmap_generic_address(struct acpi_generic_address *addr)
 {
-	void __iomem *virt;
-	unsigned long flags;
-	acpi_size size = addr->bit_width / 8;
+	struct acpi_ioremap *map;
 
 	if (addr->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
 		return;
@@ -426,13 +438,17 @@ void acpi_os_unmap_generic_address(struct acpi_generic_address *addr)
 	if (!addr->address || !addr->bit_width)
 		return;
 
-	spin_lock_irqsave(&acpi_ioremap_lock, flags);
-	virt = acpi_map_vaddr_lookup(addr->address, size);
-	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+	mutex_lock(&acpi_ioremap_lock);
+	map = acpi_map_lookup(addr->address, addr->bit_width / 8);
+	if (!map) {
+		mutex_unlock(&acpi_ioremap_lock);
+		return;
+	}
+	acpi_os_drop_map_ref(map);
+	mutex_unlock(&acpi_ioremap_lock);
 
-	acpi_os_unmap_memory(virt, size);
+	acpi_os_map_cleanup(map);
 }
-EXPORT_SYMBOL_GPL(acpi_os_unmap_generic_address);
 
 #ifdef ACPI_FUTURE_USAGE
 acpi_status