staging: ozwpan: Use slab cache for oz_urb_link allocation

Use a slab cache rather than rolling our own free list.

Signed-off-by: Christoph Jaeger <email@christophjaeger.info>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/ozwpan/ozhcd.c b/drivers/staging/ozwpan/ozhcd.c
index 30bd928..1142f57 100644 (file)
--- a/drivers/staging/ozwpan/ozhcd.c
+++ b/drivers/staging/ozwpan/ozhcd.c
@@ -45,10 +45,6 @@
  */
 #define OZ_PLAT_DEV_NAME       "ozwpan"
 
-/* Maximum number of free urb links that can be kept in the pool.
- */
-#define OZ_MAX_LINK_POOL_SIZE  16
-
 /* Get endpoint object from the containing link.
  */
 #define ep_from_link(__e) container_of((__e), struct oz_endpoint, link)
@@ -75,6 +71,8 @@ struct oz_urb_link {
        unsigned submit_counter;
 };
 
+static struct kmem_cache *oz_urb_link_cache;
+
 /* Holds state information about a USB endpoint.
  */
 #define OZ_EP_BUFFER_SIZE_ISOC  (1024 * 24)
@@ -198,9 +196,6 @@ static struct platform_device *g_plat_dev;
 static struct oz_hcd *g_ozhcd;
 static DEFINE_SPINLOCK(g_hcdlock);     /* Guards g_ozhcd. */
 static const char g_hcd_name[] = "Ozmo WPAN";
-static struct list_head *g_link_pool;
-static int g_link_pool_size;
-static DEFINE_SPINLOCK(g_link_lock);
 static DEFINE_SPINLOCK(g_tasklet_lock);
 static struct tasklet_struct g_urb_process_tasklet;
 static struct tasklet_struct g_urb_cancel_tasklet;
@@ -265,68 +260,22 @@ static int oz_get_port_from_addr(struct oz_hcd *ozhcd, u8 bus_addr)
 }
 
 /*
- * Allocates an urb link, first trying the pool but going to heap if empty.
  * Context: any
  */
 static struct oz_urb_link *oz_alloc_urb_link(void)
 {
-       struct oz_urb_link *urbl = NULL;
-       unsigned long irq_state;
-
-       spin_lock_irqsave(&g_link_lock, irq_state);
-       if (g_link_pool) {
-               urbl = container_of(g_link_pool, struct oz_urb_link, link);
-               g_link_pool = urbl->link.next;
-               --g_link_pool_size;
-       }
-       spin_unlock_irqrestore(&g_link_lock, irq_state);
-       if (urbl == NULL)
-               urbl = kmalloc(sizeof(struct oz_urb_link), GFP_ATOMIC);
-       return urbl;
+       return kmem_cache_alloc(oz_urb_link_cache, GFP_ATOMIC);
 }
 
 /*
- * Frees an urb link by putting it in the pool if there is enough space or
- * deallocating it to heap otherwise.
  * Context: any
  */
 static void oz_free_urb_link(struct oz_urb_link *urbl)
 {
-       if (urbl) {
-               unsigned long irq_state;
-
-               spin_lock_irqsave(&g_link_lock, irq_state);
-               if (g_link_pool_size < OZ_MAX_LINK_POOL_SIZE) {
-                       urbl->link.next = g_link_pool;
-                       g_link_pool = &urbl->link;
-                       urbl = NULL;
-                       g_link_pool_size++;
-               }
-               spin_unlock_irqrestore(&g_link_lock, irq_state);
-               kfree(urbl);
-       }
-}
-
-/*
- * Deallocates all the urb links in the pool.
- * Context: unknown
- */
-static void oz_empty_link_pool(void)
-{
-       struct list_head *e;
-       unsigned long irq_state;
+       if (!urbl)
+               return;
 
-       spin_lock_irqsave(&g_link_lock, irq_state);
-       e = g_link_pool;
-       g_link_pool = NULL;
-       g_link_pool_size = 0;
-       spin_unlock_irqrestore(&g_link_lock, irq_state);
-       while (e) {
-               struct oz_urb_link *urbl =
-                       container_of(e, struct oz_urb_link, link);
-               e = e->next;
-               kfree(urbl);
-       }
+       kmem_cache_free(oz_urb_link_cache, urbl);
 }
 
 /*
@@ -2311,7 +2260,6 @@ static int oz_plat_remove(struct platform_device *dev)
        oz_dbg(ON, "Removing hcd\n");
        usb_remove_hcd(hcd);
        usb_put_hcd(hcd);
-       oz_empty_link_pool();
        return 0;
 }
 
@@ -2341,6 +2289,11 @@ int oz_hcd_init(void)
 
        if (usb_disabled())
                return -ENODEV;
+
+       oz_urb_link_cache = KMEM_CACHE(oz_urb_link, 0);
+       if (!oz_urb_link_cache)
+               return -ENOMEM;
+
        tasklet_init(&g_urb_process_tasklet, oz_urb_process_tasklet, 0);
        tasklet_init(&g_urb_cancel_tasklet, oz_urb_cancel_tasklet, 0);
        err = platform_driver_register(&g_oz_plat_drv);
@@ -2380,4 +2333,5 @@ void oz_hcd_term(void)
        platform_device_unregister(g_plat_dev);
        platform_driver_unregister(&g_oz_plat_drv);
        oz_dbg(ON, "Pending urbs:%d\n", atomic_read(&g_pending_urbs));
+       kmem_cache_destroy(oz_urb_link_cache);
 }