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/usb/host/fhci.h b/drivers/usb/host/fhci.h
index 7116284..2277428 100644
--- a/drivers/usb/host/fhci.h
+++ b/drivers/usb/host/fhci.h
@@ -423,9 +423,9 @@
struct usb_td __iomem *td_base; /* first TD in the ring */
struct usb_td __iomem *conf_td; /* next TD for confirm after transac */
struct usb_td __iomem *empty_td;/* next TD for new transaction req. */
- struct kfifo *empty_frame_Q; /* Empty frames list to use */
- struct kfifo *conf_frame_Q; /* frames passed to TDs,waiting for tx */
- struct kfifo *dummy_packets_Q;/* dummy packets for the CRC overun */
+ struct kfifo empty_frame_Q; /* Empty frames list to use */
+ struct kfifo conf_frame_Q; /* frames passed to TDs,waiting for tx */
+ struct kfifo dummy_packets_Q;/* dummy packets for the CRC overun */
bool already_pushed_dummy_bd;
};
@@ -493,9 +493,9 @@
}
/* fifo of pointers */
-static inline struct kfifo *cq_new(int size)
+static inline int cq_new(struct kfifo *fifo, int size)
{
- return kfifo_alloc(size * sizeof(void *), GFP_KERNEL, NULL);
+ return kfifo_alloc(fifo, size * sizeof(void *), GFP_KERNEL, NULL);
}
static inline void cq_delete(struct kfifo *kfifo)