kfifo: move struct kfifo in place

This is a new generic kernel FIFO implementation.

The current kernel fifo API is not very widely used, because it has to
many constrains.  Only 17 files in the current 2.6.31-rc5 used it.
FIFO's are like list's a very basic thing and a kfifo API which handles
the most use case would save a lot of development time and memory
resources.

I think this are the reasons why kfifo is not in use:

 - The API is to simple, important functions are missing
 - A fifo can be only allocated dynamically
 - There is a requirement of a spinlock whether you need it or not
 - There is no support for data records inside a fifo

So I decided to extend the kfifo in a more generic way without blowing up
the API to much.  The new API has the following benefits:

 - Generic usage: For kernel internal use and/or device driver.
 - Provide an API for the most use case.
 - Slim API: The whole API provides 25 functions.
 - Linux style habit.
 - DECLARE_KFIFO, DEFINE_KFIFO and INIT_KFIFO Macros
 - Direct copy_to_user from the fifo and copy_from_user into the fifo.
 - The kfifo itself is an in place member of the using data structure, this save an
   indirection access and does not waste the kernel allocator.
 - Lockless access: if only one reader and one writer is active on the fifo,
   which is the common use case, no additional locking is necessary.
 - Remove spinlock - give the user the freedom of choice what kind of locking to use if
   one is required.
 - Ability to handle records. Three type of records are supported:
   - Variable length records between 0-255 bytes, with a record size
     field of 1 bytes.
   - Variable length records between 0-65535 bytes, with a record size
     field of 2 bytes.
   - Fixed size records, which no record size field.
 - Preserve memory resource.
 - Performance!
 - Easy to use!

This patch:

Since most users want to have the kfifo as part of another object,
reorganize the code to allow including struct kfifo in another data
structure.  This requires changing the kfifo_alloc and kfifo_init
prototypes so that we pass an existing kfifo pointer into them.  This
patch changes the implementation and all existing users.

[akpm@linux-foundation.org: fix warning]
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 9 deletions

diff --git a/drivers/net/wireless/libertas/main.c b/drivers/net/wireless/libertas/main.c
index db38a5a719fa..403909287414 100644
--- a/drivers/net/wireless/libertas/main.c
+++ b/drivers/net/wireless/libertas/main.c
@@ -459,7 +459,7 @@ static int lbs_thread(void *data)
 		else if (!list_empty(&priv->cmdpendingq) &&
 					!(priv->wakeup_dev_required))
 			shouldsleep = 0;	/* We have a command to send */
-		else if (__kfifo_len(priv->event_fifo))
+		else if (__kfifo_len(&priv->event_fifo))
 			shouldsleep = 0;	/* We have an event to process */
 		else
 			shouldsleep = 1;	/* No command */
@@ -511,9 +511,9 @@ static int lbs_thread(void *data)
 
 		/* Process hardware events, e.g. card removed, link lost */
 		spin_lock_irq(&priv->driver_lock);
-		while (__kfifo_len(priv->event_fifo)) {
+		while (__kfifo_len(&priv->event_fifo)) {
 			u32 event;
-			__kfifo_get(priv->event_fifo, (unsigned char *) &event,
+			__kfifo_get(&priv->event_fifo, (unsigned char *) &event,
 				sizeof(event));
 			spin_unlock_irq(&priv->driver_lock);
 			lbs_process_event(priv, event);
@@ -883,10 +883,9 @@ static int lbs_init_adapter(struct lbs_private *priv)
 	priv->resp_len[0] = priv->resp_len[1] = 0;
 
 	/* Create the event FIFO */
-	priv->event_fifo = kfifo_alloc(sizeof(u32) * 16, GFP_KERNEL, NULL);
-	if (IS_ERR(priv->event_fifo)) {
+	ret = kfifo_alloc(&priv->event_fifo, sizeof(u32) * 16, GFP_KERNEL, NULL);
+	if (ret) {
 		lbs_pr_err("Out of memory allocating event FIFO buffer\n");
-		ret = -ENOMEM;
 		goto out;
 	}
 
@@ -901,8 +900,7 @@ static void lbs_free_adapter(struct lbs_private *priv)
 	lbs_deb_enter(LBS_DEB_MAIN);
 
 	lbs_free_cmd_buffer(priv);
-	if (priv->event_fifo)
-		kfifo_free(priv->event_fifo);
+	kfifo_free(&priv->event_fifo);
 	del_timer(&priv->command_timer);
 	del_timer(&priv->auto_deepsleep_timer);
 	kfree(priv->networks);
@@ -1177,7 +1175,7 @@ void lbs_queue_event(struct lbs_private *priv, u32 event)
 	if (priv->psstate == PS_STATE_SLEEP)
 		priv->psstate = PS_STATE_AWAKE;
 
-	__kfifo_put(priv->event_fifo, (unsigned char *) &event, sizeof(u32));
+	__kfifo_put(&priv->event_fifo, (unsigned char *) &event, sizeof(u32));
 
 	wake_up_interruptible(&priv->waitq);