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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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| .. | ||
| whci | ||
| ehci-atmel.c | ||
| ehci-au1xxx.c | ||
| ehci-dbg.c | ||
| ehci-fsl.c | ||
| ehci-fsl.h | ||
| ehci-hcd.c | ||
| ehci-hub.c | ||
| ehci-ixp4xx.c | ||
| ehci-mem.c | ||
| ehci-mxc.c | ||
| ehci-omap.c | ||
| ehci-orion.c | ||
| ehci-pci.c | ||
| ehci-ppc-of.c | ||
| ehci-ps3.c | ||
| ehci-q.c | ||
| ehci-sched.c | ||
| ehci-w90x900.c | ||
| ehci-xilinx-of.c | ||
| ehci.h | ||
| fhci-dbg.c | ||
| fhci-hcd.c | ||
| fhci-hub.c | ||
| fhci-mem.c | ||
| fhci-q.c | ||
| fhci-sched.c | ||
| fhci-tds.c | ||
| fhci.h | ||
| hwa-hc.c | ||
| isp116x-hcd.c | ||
| isp116x.h | ||
| isp1362-hcd.c | ||
| isp1362.h | ||
| isp1760-hcd.c | ||
| isp1760-hcd.h | ||
| isp1760-if.c | ||
| Kconfig | ||
| Makefile | ||
| ohci-at91.c | ||
| ohci-au1xxx.c | ||
| ohci-dbg.c | ||
| ohci-ep93xx.c | ||
| ohci-hcd.c | ||
| ohci-hub.c | ||
| ohci-lh7a404.c | ||
| ohci-mem.c | ||
| ohci-omap.c | ||
| ohci-pci.c | ||
| ohci-pnx4008.c | ||
| ohci-pnx8550.c | ||
| ohci-ppc-of.c | ||
| ohci-ppc-soc.c | ||
| ohci-ps3.c | ||
| ohci-pxa27x.c | ||
| ohci-q.c | ||
| ohci-s3c2410.c | ||
| ohci-sa1111.c | ||
| ohci-sh.c | ||
| ohci-sm501.c | ||
| ohci-ssb.c | ||
| ohci-tmio.c | ||
| ohci.h | ||
| oxu210hp-hcd.c | ||
| oxu210hp.h | ||
| pci-quirks.c | ||
| pci-quirks.h | ||
| r8a66597-hcd.c | ||
| r8a66597.h | ||
| sl811_cs.c | ||
| sl811-hcd.c | ||
| sl811.h | ||
| u132-hcd.c | ||
| uhci-debug.c | ||
| uhci-hcd.c | ||
| uhci-hcd.h | ||
| uhci-hub.c | ||
| uhci-q.c | ||
| xhci-dbg.c | ||
| xhci-ext-caps.h | ||
| xhci-hcd.c | ||
| xhci-hub.c | ||
| xhci-mem.c | ||
| xhci-pci.c | ||
| xhci-ring.c | ||
| xhci.h | ||