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, 19 insertions, 21 deletions

diff --git a/drivers/char/sonypi.c b/drivers/char/sonypi.c
index 8c262aaf7c26..9e6efb1f029f 100644
--- a/drivers/char/sonypi.c
+++ b/drivers/char/sonypi.c
@@ -487,7 +487,7 @@ static struct sonypi_device {
         int camera_power;
         int bluetooth_power;
         struct mutex lock;
-        struct kfifo *fifo;
+        struct kfifo fifo;
         spinlock_t fifo_lock;
         wait_queue_head_t fifo_proc_list;
         struct fasync_struct *fifo_async;
@@ -496,7 +496,7 @@ static struct sonypi_device {
         struct input_dev *input_jog_dev;
         struct input_dev *input_key_dev;
         struct work_struct input_work;
-        struct kfifo *input_fifo;
+        struct kfifo input_fifo;
         spinlock_t input_fifo_lock;
 } sonypi_device;
 
@@ -777,7 +777,7 @@ static void input_keyrelease(struct work_struct *work)
 {
         struct sonypi_keypress kp;
 
-        while (kfifo_get(sonypi_device.input_fifo, (unsigned char *)&kp,
+        while (kfifo_get(&sonypi_device.input_fifo, (unsigned char *)&kp,
                          sizeof(kp)) == sizeof(kp)) {
                 msleep(10);
                 input_report_key(kp.dev, kp.key, 0);
@@ -827,7 +827,7 @@ static void sonypi_report_input_event(u8 event)
         if (kp.dev) {
                 input_report_key(kp.dev, kp.key, 1);
                 input_sync(kp.dev);
-                kfifo_put(sonypi_device.input_fifo,
+                kfifo_put(&sonypi_device.input_fifo,
                           (unsigned char *)&kp, sizeof(kp));
                 schedule_work(&sonypi_device.input_work);
         }
@@ -880,7 +880,7 @@ found:
                 acpi_bus_generate_proc_event(sonypi_acpi_device, 1, event);
 #endif
 
-        kfifo_put(sonypi_device.fifo, (unsigned char *)&event, sizeof(event));
+        kfifo_put(&sonypi_device.fifo, (unsigned char *)&event, sizeof(event));
         kill_fasync(&sonypi_device.fifo_async, SIGIO, POLL_IN);
         wake_up_interruptible(&sonypi_device.fifo_proc_list);
 
@@ -906,7 +906,7 @@ static int sonypi_misc_open(struct inode *inode, struct file *file)
         mutex_lock(&sonypi_device.lock);
         /* Flush input queue on first open */
         if (!sonypi_device.open_count)
-                kfifo_reset(sonypi_device.fifo);
+                kfifo_reset(&sonypi_device.fifo);
         sonypi_device.open_count++;
         mutex_unlock(&sonypi_device.lock);
         unlock_kernel();
@@ -919,17 +919,17 @@ static ssize_t sonypi_misc_read(struct file *file, char __user *buf,
         ssize_t ret;
         unsigned char c;
 
-        if ((kfifo_len(sonypi_device.fifo) == 0) &&
+        if ((kfifo_len(&sonypi_device.fifo) == 0) &&
             (file->f_flags & O_NONBLOCK))
                 return -EAGAIN;
 
         ret = wait_event_interruptible(sonypi_device.fifo_proc_list,
-                                       kfifo_len(sonypi_device.fifo) != 0);
+                                       kfifo_len(&sonypi_device.fifo) != 0);
         if (ret)
                 return ret;
 
         while (ret < count &&
-               (kfifo_get(sonypi_device.fifo, &c, sizeof(c)) == sizeof(c))) {
+               (kfifo_get(&sonypi_device.fifo, &c, sizeof(c)) == sizeof(c))) {
                 if (put_user(c, buf++))
                         return -EFAULT;
                 ret++;
@@ -946,7 +946,7 @@ 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_device.fifo_proc_list, wait);
-        if (kfifo_len(sonypi_device.fifo))
+        if (kfifo_len(&sonypi_device.fifo))
                 return POLLIN | POLLRDNORM;
         return 0;
 }
@@ -1313,11 +1313,11 @@ static int __devinit sonypi_probe(struct platform_device *dev)
                         "http://www.linux.it/~malattia/wiki/index.php/Sony_drivers\n");
 
         spin_lock_init(&sonypi_device.fifo_lock);
-        sonypi_device.fifo = kfifo_alloc(SONYPI_BUF_SIZE, GFP_KERNEL,
+        error = kfifo_alloc(&sonypi_device.fifo, SONYPI_BUF_SIZE, GFP_KERNEL,
                                          &sonypi_device.fifo_lock);
-        if (IS_ERR(sonypi_device.fifo)) {
+        if (error) {
                 printk(KERN_ERR "sonypi: kfifo_alloc failed\n");
-                return PTR_ERR(sonypi_device.fifo);
+                return error;
         }
 
         init_waitqueue_head(&sonypi_device.fifo_proc_list);
@@ -1393,12 +1393,10 @@ static int __devinit sonypi_probe(struct platform_device *dev)
                 }
 
                 spin_lock_init(&sonypi_device.input_fifo_lock);
-                sonypi_device.input_fifo =
-                        kfifo_alloc(SONYPI_BUF_SIZE, GFP_KERNEL,
-                                    &sonypi_device.input_fifo_lock);
-                if (IS_ERR(sonypi_device.input_fifo)) {
+                error = kfifo_alloc(&sonypi_device.input_fifo, SONYPI_BUF_SIZE,
+                                GFP_KERNEL, &sonypi_device.input_fifo_lock);
+                if (error) {
                         printk(KERN_ERR "sonypi: kfifo_alloc failed\n");
-                        error = PTR_ERR(sonypi_device.input_fifo);
                         goto err_inpdev_unregister;
                 }
 
@@ -1423,7 +1421,7 @@ static int __devinit sonypi_probe(struct platform_device *dev)
                 pci_disable_device(pcidev);
  err_put_pcidev:
         pci_dev_put(pcidev);
-        kfifo_free(sonypi_device.fifo);
+        kfifo_free(&sonypi_device.fifo);
 
         return error;
 }
@@ -1438,7 +1436,7 @@ static int __devexit sonypi_remove(struct platform_device *dev)
         if (useinput) {
                 input_unregister_device(sonypi_device.input_key_dev);
                 input_unregister_device(sonypi_device.input_jog_dev);
-                kfifo_free(sonypi_device.input_fifo);
+                kfifo_free(&sonypi_device.input_fifo);
         }
 
         misc_deregister(&sonypi_misc_device);
@@ -1451,7 +1449,7 @@ static int __devexit sonypi_remove(struct platform_device *dev)
                 pci_dev_put(sonypi_device.dev);
         }
 
-        kfifo_free(sonypi_device.fifo);
+        kfifo_free(&sonypi_device.fifo);
 
         return 0;
 }