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, 25 insertions, 27 deletions

diff --git a/drivers/media/video/meye.c b/drivers/media/video/meye.c
index 6ffa64cd1c6d..dacbbb839b9e 100644
--- a/drivers/media/video/meye.c
+++ b/drivers/media/video/meye.c
@@ -800,7 +800,7 @@ again:
 		return IRQ_HANDLED;
 
 	if (meye.mchip_mode == MCHIP_HIC_MODE_CONT_OUT) {
-		if (kfifo_get(meye.grabq, (unsigned char *)&reqnr,
+		if (kfifo_get(&meye.grabq, (unsigned char *)&reqnr,
 			      sizeof(int)) != sizeof(int)) {
 			mchip_free_frame();
 			return IRQ_HANDLED;
@@ -811,7 +811,7 @@ again:
 		meye.grab_buffer[reqnr].state = MEYE_BUF_DONE;
 		do_gettimeofday(&meye.grab_buffer[reqnr].timestamp);
 		meye.grab_buffer[reqnr].sequence = sequence++;
-		kfifo_put(meye.doneq, (unsigned char *)&reqnr, sizeof(int));
+		kfifo_put(&meye.doneq, (unsigned char *)&reqnr, sizeof(int));
 		wake_up_interruptible(&meye.proc_list);
 	} else {
 		int size;
@@ -820,7 +820,7 @@ again:
 			mchip_free_frame();
 			goto again;
 		}
-		if (kfifo_get(meye.grabq, (unsigned char *)&reqnr,
+		if (kfifo_get(&meye.grabq, (unsigned char *)&reqnr,
 			      sizeof(int)) != sizeof(int)) {
 			mchip_free_frame();
 			goto again;
@@ -831,7 +831,7 @@ again:
 		meye.grab_buffer[reqnr].state = MEYE_BUF_DONE;
 		do_gettimeofday(&meye.grab_buffer[reqnr].timestamp);
 		meye.grab_buffer[reqnr].sequence = sequence++;
-		kfifo_put(meye.doneq, (unsigned char *)&reqnr, sizeof(int));
+		kfifo_put(&meye.doneq, (unsigned char *)&reqnr, sizeof(int));
 		wake_up_interruptible(&meye.proc_list);
 	}
 	mchip_free_frame();
@@ -859,8 +859,8 @@ static int meye_open(struct file *file)
 
 	for (i = 0; i < MEYE_MAX_BUFNBRS; i++)
 		meye.grab_buffer[i].state = MEYE_BUF_UNUSED;
-	kfifo_reset(meye.grabq);
-	kfifo_reset(meye.doneq);
+	kfifo_reset(&meye.grabq);
+	kfifo_reset(&meye.doneq);
 	return 0;
 }
 
@@ -933,7 +933,7 @@ static int meyeioc_qbuf_capt(int *nb)
 		mchip_cont_compression_start();
 
 	meye.grab_buffer[*nb].state = MEYE_BUF_USING;
-	kfifo_put(meye.grabq, (unsigned char *)nb, sizeof(int));
+	kfifo_put(&meye.grabq, (unsigned char *)nb, sizeof(int));
 	mutex_unlock(&meye.lock);
 
 	return 0;
@@ -965,7 +965,7 @@ static int meyeioc_sync(struct file *file, void *fh, int *i)
 		/* fall through */
 	case MEYE_BUF_DONE:
 		meye.grab_buffer[*i].state = MEYE_BUF_UNUSED;
-		kfifo_get(meye.doneq, (unsigned char *)&unused, sizeof(int));
+		kfifo_get(&meye.doneq, (unsigned char *)&unused, sizeof(int));
 	}
 	*i = meye.grab_buffer[*i].size;
 	mutex_unlock(&meye.lock);
@@ -1452,7 +1452,7 @@ static int vidioc_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
 	buf->flags |= V4L2_BUF_FLAG_QUEUED;
 	buf->flags &= ~V4L2_BUF_FLAG_DONE;
 	meye.grab_buffer[buf->index].state = MEYE_BUF_USING;
-	kfifo_put(meye.grabq, (unsigned char *)&buf->index, sizeof(int));
+	kfifo_put(&meye.grabq, (unsigned char *)&buf->index, sizeof(int));
 	mutex_unlock(&meye.lock);
 
 	return 0;
@@ -1467,18 +1467,18 @@ static int vidioc_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
 
 	mutex_lock(&meye.lock);
 
-	if (kfifo_len(meye.doneq) == 0 && file->f_flags & O_NONBLOCK) {
+	if (kfifo_len(&meye.doneq) == 0 && file->f_flags & O_NONBLOCK) {
 		mutex_unlock(&meye.lock);
 		return -EAGAIN;
 	}
 
 	if (wait_event_interruptible(meye.proc_list,
-				     kfifo_len(meye.doneq) != 0) < 0) {
+				     kfifo_len(&meye.doneq) != 0) < 0) {
 		mutex_unlock(&meye.lock);
 		return -EINTR;
 	}
 
-	if (!kfifo_get(meye.doneq, (unsigned char *)&reqnr,
+	if (!kfifo_get(&meye.doneq, (unsigned char *)&reqnr,
 		       sizeof(int))) {
 		mutex_unlock(&meye.lock);
 		return -EBUSY;
@@ -1529,8 +1529,8 @@ static int vidioc_streamoff(struct file *file, void *fh, enum v4l2_buf_type i)
 {
 	mutex_lock(&meye.lock);
 	mchip_hic_stop();
-	kfifo_reset(meye.grabq);
-	kfifo_reset(meye.doneq);
+	kfifo_reset(&meye.grabq);
+	kfifo_reset(&meye.doneq);
 
 	for (i = 0; i < MEYE_MAX_BUFNBRS; i++)
 		meye.grab_buffer[i].state = MEYE_BUF_UNUSED;
@@ -1572,7 +1572,7 @@ static unsigned int meye_poll(struct file *file, poll_table *wait)
 
 	mutex_lock(&meye.lock);
 	poll_wait(file, &meye.proc_list, wait);
-	if (kfifo_len(meye.doneq))
+	if (kfifo_len(&meye.doneq))
 		res = POLLIN | POLLRDNORM;
 	mutex_unlock(&meye.lock);
 	return res;
@@ -1745,16 +1745,14 @@ static int __devinit meye_probe(struct pci_dev *pcidev,
 	}
 
 	spin_lock_init(&meye.grabq_lock);
-	meye.grabq = kfifo_alloc(sizeof(int) * MEYE_MAX_BUFNBRS, GFP_KERNEL,
-				 &meye.grabq_lock);
-	if (IS_ERR(meye.grabq)) {
+	if (kfifo_alloc(&meye.grabq, sizeof(int) * MEYE_MAX_BUFNBRS, GFP_KERNEL,
+				 &meye.grabq_lock)) {
 		printk(KERN_ERR "meye: fifo allocation failed\n");
 		goto outkfifoalloc1;
 	}
 	spin_lock_init(&meye.doneq_lock);
-	meye.doneq = kfifo_alloc(sizeof(int) * MEYE_MAX_BUFNBRS, GFP_KERNEL,
-				 &meye.doneq_lock);
-	if (IS_ERR(meye.doneq)) {
+	if (kfifo_alloc(&meye.doneq, sizeof(int) * MEYE_MAX_BUFNBRS, GFP_KERNEL,
+				 &meye.doneq_lock)) {
 		printk(KERN_ERR "meye: fifo allocation failed\n");
 		goto outkfifoalloc2;
 	}
@@ -1868,9 +1866,9 @@ outregions:
 outenabledev:
 	sony_pic_camera_command(SONY_PIC_COMMAND_SETCAMERA, 0);
 outsonypienable:
-	kfifo_free(meye.doneq);
+	kfifo_free(&meye.doneq);
 outkfifoalloc2:
-	kfifo_free(meye.grabq);
+	kfifo_free(&meye.grabq);
 outkfifoalloc1:
 	vfree(meye.grab_temp);
 outvmalloc:
@@ -1901,8 +1899,8 @@ static void __devexit meye_remove(struct pci_dev *pcidev)
 
 	sony_pic_camera_command(SONY_PIC_COMMAND_SETCAMERA, 0);
 
-	kfifo_free(meye.doneq);
-	kfifo_free(meye.grabq);
+	kfifo_free(&meye.doneq);
+	kfifo_free(&meye.grabq);
 
 	vfree(meye.grab_temp);
 
diff --git a/drivers/media/video/meye.h b/drivers/media/video/meye.h
index 5f70a106ba2b..1321ad5d6597 100644
--- a/drivers/media/video/meye.h
+++ b/drivers/media/video/meye.h
@@ -303,9 +303,9 @@ struct meye {
 	struct meye_grab_buffer grab_buffer[MEYE_MAX_BUFNBRS];
 	int vma_use_count[MEYE_MAX_BUFNBRS]; /* mmap count */
 	struct mutex lock;		/* mutex for open/mmap... */
-	struct kfifo *grabq;		/* queue for buffers to be grabbed */
+	struct kfifo grabq;		/* queue for buffers to be grabbed */
 	spinlock_t grabq_lock;		/* lock protecting the queue */
-	struct kfifo *doneq;		/* queue for grabbed buffers */
+	struct kfifo doneq;		/* queue for grabbed buffers */
 	spinlock_t doneq_lock;		/* lock protecting the queue */
 	wait_queue_head_t proc_list;	/* wait queue */
 	struct video_device *video_dev;	/* video device parameters */