ACPI: Convert simple locking to RCU based locking

Convert the simple locking introduced earlier for the ACPI MMIO
remappings list to an RCU based locking scheme.

Signed-off-by: Myron Stowe <myron.stowe@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index c63d4cb..3282689 100644 (file)
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -244,13 +244,13 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
        }
 }
 
-/* Must be called with 'acpi_ioremap_lock' lock held. */
+/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */
 static void __iomem *
 acpi_map_vaddr_lookup(acpi_physical_address phys, acpi_size size)
 {
        struct acpi_ioremap *map;
 
-       list_for_each_entry(map, &acpi_ioremaps, list)
+       list_for_each_entry_rcu(map, &acpi_ioremaps, list)
                if (map->phys <= phys &&
                    phys + size <= map->phys + map->size)
                        return map->virt + (phys - map->phys);
@@ -258,13 +258,13 @@ acpi_map_vaddr_lookup(acpi_physical_address phys, acpi_size size)
        return NULL;
 }
 
-/* Must be called with 'acpi_ioremap_lock' lock held. */
+/* 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)
 {
        struct acpi_ioremap *map;
 
-       list_for_each_entry(map, &acpi_ioremaps, list)
+       list_for_each_entry_rcu(map, &acpi_ioremaps, list)
                if (map->virt == virt && map->size == size)
                        return map;
 
@@ -302,7 +302,7 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
        map->size = size;
 
        spin_lock_irqsave(&acpi_ioremap_lock, flags);
-       list_add_tail(&map->list, &acpi_ioremaps);
+       list_add_tail_rcu(&map->list, &acpi_ioremaps);
        spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 
        return virt;
@@ -328,9 +328,10 @@ void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
                return;
        }
 
-       list_del(&map->list);
+       list_del_rcu(&map->list);
        spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 
+       synchronize_rcu();
        iounmap(map->virt);
        kfree(map);
 }
@@ -584,11 +585,10 @@ acpi_os_read_memory(acpi_physical_address phys_addr, u32 * value, u32 width)
        u32 dummy;
        void __iomem *virt_addr;
        int size = width / 8, unmap = 0;
-       unsigned long flags;
 
-       spin_lock_irqsave(&acpi_ioremap_lock, flags);
+       rcu_read_lock();
        virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
-       spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+       rcu_read_unlock();
        if (!virt_addr) {
                virt_addr = ioremap(phys_addr, size);
                unmap = 1;
@@ -621,11 +621,10 @@ acpi_os_write_memory(acpi_physical_address phys_addr, u32 value, u32 width)
 {
        void __iomem *virt_addr;
        int size = width / 8, unmap = 0;
-       unsigned long flags;
 
-       spin_lock_irqsave(&acpi_ioremap_lock, flags);
+       rcu_read_lock();
        virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
-       spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+       rcu_read_unlock();
        if (!virt_addr) {
                virt_addr = ioremap(phys_addr, size);
                unmap = 1;