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4546548789
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>
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| b43legacy | ||
| hostap | ||
| ipw2x00 | ||
| iwlwifi | ||
| iwmc3200wifi | ||
| libertas | ||
| libertas_tf | ||
| orinoco | ||
| p54 | ||
| prism54 | ||
| rt2x00 | ||
| rtl818x | ||
| wl12xx | ||
| zd1211rw | ||
| adm8211.c | ||
| adm8211.h | ||
| airo_cs.c | ||
| airo.c | ||
| airo.h | ||
| at76c50x-usb.c | ||
| at76c50x-usb.h | ||
| atmel_cs.c | ||
| atmel_pci.c | ||
| atmel.c | ||
| atmel.h | ||
| Kconfig | ||
| mac80211_hwsim.c | ||
| Makefile | ||
| mwl8k.c | ||
| ray_cs.c | ||
| ray_cs.h | ||
| rayctl.h | ||
| rndis_wlan.c | ||
| wl3501_cs.c | ||
| wl3501.h | ||
| zd1201.c | ||
| zd1201.h | ||