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/fujitsu-laptop.c b/drivers/platform/x86/fujitsu-laptop.c
index bcd4ba8..f999fba 100644
--- a/drivers/platform/x86/fujitsu-laptop.c
+++ b/drivers/platform/x86/fujitsu-laptop.c
@@ -164,7 +164,7 @@
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 @@
/* 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_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 @@
input_free_device(input);
- kfifo_free(fujitsu_hotkey->fifo);
+ kfifo_free(&fujitsu_hotkey->fifo);
fujitsu_hotkey->acpi_handle = NULL;
@@ -1008,7 +1006,7 @@
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 @@
} 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)) {