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>

2 files changed, 31 insertions, 33 deletions

diff --git a/drivers/platform/x86/fujitsu-laptop.c b/drivers/platform/x86/fujitsu-laptop.c
index bcd4ba8be7d..f999fba0e25 100644
--- a/drivers/platform/x86/fujitsu-laptop.c
+++ b/drivers/platform/x86/fujitsu-laptop.c
@@ -164,7 +164,7 @@ struct fujitsu_hotkey_t {
 	struct input_dev *input;
 	char phys[32];
 	struct platform_device *pf_device;
-	struct kfifo *fifo;
+	struct kfifo fifo;
 	spinlock_t fifo_lock;
 	int rfkill_supported;
 	int rfkill_state;
@@ -824,12 +824,10 @@ static int acpi_fujitsu_hotkey_add(struct acpi_device *device)
 
 	/* kfifo */
 	spin_lock_init(&fujitsu_hotkey->fifo_lock);
-	fujitsu_hotkey->fifo =
-	    kfifo_alloc(RINGBUFFERSIZE * sizeof(int), GFP_KERNEL,
-			&fujitsu_hotkey->fifo_lock);
-	if (IS_ERR(fujitsu_hotkey->fifo)) {
+	error = kfifo_alloc(&fujitsu_hotkey->fifo, RINGBUFFERSIZE * sizeof(int),
+			GFP_KERNEL, &fujitsu_hotkey->fifo_lock);
+	if (error) {
 		printk(KERN_ERR "kfifo_alloc failed\n");
-		error = PTR_ERR(fujitsu_hotkey->fifo);
 		goto err_stop;
 	}
 
@@ -934,7 +932,7 @@ err_unregister_input_dev:
 err_free_input_dev:
 	input_free_device(input);
 err_free_fifo:
-	kfifo_free(fujitsu_hotkey->fifo);
+	kfifo_free(&fujitsu_hotkey->fifo);
 err_stop:
 	return result;
 }
@@ -956,7 +954,7 @@ static int acpi_fujitsu_hotkey_remove(struct acpi_device *device, int type)
 
 	input_free_device(input);
 
-	kfifo_free(fujitsu_hotkey->fifo);
+	kfifo_free(&fujitsu_hotkey->fifo);
 
 	fujitsu_hotkey->acpi_handle = NULL;
 
@@ -1008,7 +1006,7 @@ static void acpi_fujitsu_hotkey_notify(struct acpi_device *device, u32 event)
 				vdbg_printk(FUJLAPTOP_DBG_TRACE,
 					"Push keycode into ringbuffer [%d]\n",
 					keycode);
-				status = kfifo_put(fujitsu_hotkey->fifo,
+				status = kfifo_put(&fujitsu_hotkey->fifo,
 						   (unsigned char *)&keycode,
 						   sizeof(keycode));
 				if (status != sizeof(keycode)) {
@@ -1022,7 +1020,7 @@ static void acpi_fujitsu_hotkey_notify(struct acpi_device *device, u32 event)
 			} else if (keycode == 0) {
 				while ((status =
 					kfifo_get
-					(fujitsu_hotkey->fifo, (unsigned char *)
+					(&fujitsu_hotkey->fifo, (unsigned char *)
 					 &keycode_r,
 					 sizeof
 					 (keycode_r))) == sizeof(keycode_r)) {
diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
index 7a2cc8a5c97..04625a048e7 100644
--- a/drivers/platform/x86/sony-laptop.c
+++ b/drivers/platform/x86/sony-laptop.c
@@ -142,7 +142,7 @@ struct sony_laptop_input_s {
 	atomic_t		users;
 	struct input_dev	*jog_dev;
 	struct input_dev	*key_dev;
-	struct kfifo		*fifo;
+	struct kfifo		fifo;
 	spinlock_t		fifo_lock;
 	struct workqueue_struct	*wq;
 };
@@ -300,7 +300,7 @@ static void do_sony_laptop_release_key(struct work_struct *work)
 {
 	struct sony_laptop_keypress kp;
 
-	while (kfifo_get(sony_laptop_input.fifo, (unsigned char *)&kp,
+	while (kfifo_get(&sony_laptop_input.fifo, (unsigned char *)&kp,
 			 sizeof(kp)) == sizeof(kp)) {
 		msleep(10);
 		input_report_key(kp.dev, kp.key, 0);
@@ -362,7 +362,7 @@ static void sony_laptop_report_input_event(u8 event)
 		/* we emit the scancode so we can always remap the key */
 		input_event(kp.dev, EV_MSC, MSC_SCAN, event);
 		input_sync(kp.dev);
-		kfifo_put(sony_laptop_input.fifo,
+		kfifo_put(&sony_laptop_input.fifo,
 			  (unsigned char *)&kp, sizeof(kp));
 
 		if (!work_pending(&sony_laptop_release_key_work))
@@ -385,12 +385,11 @@ static int sony_laptop_setup_input(struct acpi_device *acpi_device)
 
 	/* kfifo */
 	spin_lock_init(&sony_laptop_input.fifo_lock);
-	sony_laptop_input.fifo =
-		kfifo_alloc(SONY_LAPTOP_BUF_SIZE, GFP_KERNEL,
+	error =
+	 kfifo_alloc(&sony_laptop_input.fifo, SONY_LAPTOP_BUF_SIZE, GFP_KERNEL,
 			    &sony_laptop_input.fifo_lock);
-	if (IS_ERR(sony_laptop_input.fifo)) {
+	if (error) {
 		printk(KERN_ERR DRV_PFX "kfifo_alloc failed\n");
-		error = PTR_ERR(sony_laptop_input.fifo);
 		goto err_dec_users;
 	}
 
@@ -474,7 +473,7 @@ err_destroy_wq:
 	destroy_workqueue(sony_laptop_input.wq);
 
 err_free_kfifo:
-	kfifo_free(sony_laptop_input.fifo);
+	kfifo_free(&sony_laptop_input.fifo);
 
 err_dec_users:
 	atomic_dec(&sony_laptop_input.users);
@@ -500,7 +499,7 @@ static void sony_laptop_remove_input(void)
 	}
 
 	destroy_workqueue(sony_laptop_input.wq);
-	kfifo_free(sony_laptop_input.fifo);
+	kfifo_free(&sony_laptop_input.fifo);
 }
 
 /*********** Platform Device ***********/
@@ -2079,7 +2078,7 @@ static struct attribute_group spic_attribute_group = {
 
 struct sonypi_compat_s {
 	struct fasync_struct	*fifo_async;
-	struct kfifo		*fifo;
+	struct kfifo		fifo;
 	spinlock_t		fifo_lock;
 	wait_queue_head_t	fifo_proc_list;
 	atomic_t		open_count;
@@ -2104,12 +2103,12 @@ static int sonypi_misc_open(struct inode *inode, struct file *file)
 	/* Flush input queue on first open */
 	unsigned long flags;
 
-	spin_lock_irqsave(sonypi_compat.fifo->lock, flags);
+	spin_lock_irqsave(&sonypi_compat.fifo_lock, flags);
 
 	if (atomic_inc_return(&sonypi_compat.open_count) == 1)
-		__kfifo_reset(sonypi_compat.fifo);
+		__kfifo_reset(&sonypi_compat.fifo);
 
-	spin_unlock_irqrestore(sonypi_compat.fifo->lock, flags);
+	spin_unlock_irqrestore(&sonypi_compat.fifo_lock, flags);
 
 	return 0;
 }
@@ -2120,17 +2119,17 @@ static ssize_t sonypi_misc_read(struct file *file, char __user *buf,
 	ssize_t ret;
 	unsigned char c;
 
-	if ((kfifo_len(sonypi_compat.fifo) == 0) &&
+	if ((kfifo_len(&sonypi_compat.fifo) == 0) &&
 	    (file->f_flags & O_NONBLOCK))
 		return -EAGAIN;
 
 	ret = wait_event_interruptible(sonypi_compat.fifo_proc_list,
-				       kfifo_len(sonypi_compat.fifo) != 0);
+				       kfifo_len(&sonypi_compat.fifo) != 0);
 	if (ret)
 		return ret;
 
 	while (ret < count &&
-	       (kfifo_get(sonypi_compat.fifo, &c, sizeof(c)) == sizeof(c))) {
+	       (kfifo_get(&sonypi_compat.fifo, &c, sizeof(c)) == sizeof(c))) {
 		if (put_user(c, buf++))
 			return -EFAULT;
 		ret++;
@@ -2147,7 +2146,7 @@ static ssize_t sonypi_misc_read(struct file *file, char __user *buf,
 static unsigned int sonypi_misc_poll(struct file *file, poll_table *wait)
 {
 	poll_wait(file, &sonypi_compat.fifo_proc_list, wait);
-	if (kfifo_len(sonypi_compat.fifo))
+	if (kfifo_len(&sonypi_compat.fifo))
 		return POLLIN | POLLRDNORM;
 	return 0;
 }
@@ -2309,7 +2308,7 @@ static struct miscdevice sonypi_misc_device = {
 
 static void sonypi_compat_report_event(u8 event)
 {
-	kfifo_put(sonypi_compat.fifo, (unsigned char *)&event, sizeof(event));
+	kfifo_put(&sonypi_compat.fifo, (unsigned char *)&event, sizeof(event));
 	kill_fasync(&sonypi_compat.fifo_async, SIGIO, POLL_IN);
 	wake_up_interruptible(&sonypi_compat.fifo_proc_list);
 }
@@ -2319,11 +2318,12 @@ static int sonypi_compat_init(void)
 	int error;
 
 	spin_lock_init(&sonypi_compat.fifo_lock);
-	sonypi_compat.fifo = kfifo_alloc(SONY_LAPTOP_BUF_SIZE, GFP_KERNEL,
+	error =
+	 kfifo_alloc(&sonypi_compat.fifo, SONY_LAPTOP_BUF_SIZE, GFP_KERNEL,
 					 &sonypi_compat.fifo_lock);
-	if (IS_ERR(sonypi_compat.fifo)) {
+	if (error) {
 		printk(KERN_ERR DRV_PFX "kfifo_alloc failed\n");
-		return PTR_ERR(sonypi_compat.fifo);
+		return error;
 	}
 
 	init_waitqueue_head(&sonypi_compat.fifo_proc_list);
@@ -2342,14 +2342,14 @@ static int sonypi_compat_init(void)
 	return 0;
 
 err_free_kfifo:
-	kfifo_free(sonypi_compat.fifo);
+	kfifo_free(&sonypi_compat.fifo);
 	return error;
 }
 
 static void sonypi_compat_exit(void)
 {
 	misc_deregister(&sonypi_misc_device);
-	kfifo_free(sonypi_compat.fifo);
+	kfifo_free(&sonypi_compat.fifo);
 }
 #else
 static int sonypi_compat_init(void) { return 0; }