aha/include
Stefani Seibold 4546548789 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>
2009-12-22 14:17:55 -08:00
..
acpi Merge branch 'ost' into release 2009-12-16 02:18:36 -05:00
asm-generic fix up O_SYNC comments 2009-12-17 11:03:24 -05:00
crypto
drm Merge branch 'drm-vmware-staging' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 2009-12-16 13:19:31 -08:00
keys
linux kfifo: move struct kfifo in place 2009-12-22 14:17:55 -08:00
math-emu math-emu: Fix thinko in _FP_DIV 2008-10-22 22:09:59 -07:00
media V4L/DVB (13670): soc-camera: Add mt9t112 camera driver 2009-12-16 09:27:41 -02:00
mtd
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2009-12-16 10:33:18 -08:00
pcmcia pcmcia: CodingStyle fixes 2009-12-07 22:23:40 +01:00
rdma Merge branches 'amso1100', 'cma', 'cxgb3', 'ehca', 'ipath', 'ipoib', 'iser', 'misc', 'mlx4' and 'nes' into for-next 2009-12-15 23:39:25 -08:00
rxrpc [AF_RXRPC]: Delete the old RxRPC code. 2007-04-26 15:55:48 -07:00
scsi kfifo: move struct kfifo in place 2009-12-22 14:17:55 -08:00
sound Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
trace Merge branch 'linus' into tracing/urgent 2009-12-14 09:16:49 +01:00
video Merge git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6 2009-12-16 10:29:52 -08:00
xen
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