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>
diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
index 7a2cc8a..04625a0 100644
--- a/drivers/platform/x86/sony-laptop.c
+++ b/drivers/platform/x86/sony-laptop.c
@@ -142,7 +142,7 @@
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 @@
{
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 @@
/* 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 @@
/* 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 @@
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 @@
}
destroy_workqueue(sony_laptop_input.wq);
- kfifo_free(sony_laptop_input.fifo);
+ kfifo_free(&sony_laptop_input.fifo);
}
/*********** Platform Device ***********/
@@ -2079,7 +2078,7 @@
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 @@
/* 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 @@
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 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 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 @@
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 @@
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; }
