lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

kfifo: move struct kfifo in place

Browse Source 
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>
This commit is contained in:
Stefani Seibold
2009-12-21 14:37:26 -08:00
committed by Linus Torvalds
parent 2ec91eec47
commit 4546548789
24 changed files with 238 additions and 259 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
drivers/char/sonypi.c
View File

@@ -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;
}