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-sched.c b/drivers/usb/host/fhci-sched.c
index 00a2985..ff43747 100644
--- a/drivers/usb/host/fhci-sched.c
+++ b/drivers/usb/host/fhci-sched.c
@@ -37,7 +37,7 @@
pkt->info = 0;
pkt->priv_data = NULL;
- cq_put(usb->ep0->empty_frame_Q, pkt);
+ cq_put(&usb->ep0->empty_frame_Q, pkt);
}
/* confirm submitted packet */
@@ -57,7 +57,7 @@
if ((td->data + td->actual_len) && trans_len)
memcpy(td->data + td->actual_len, pkt->data,
trans_len);
- cq_put(usb->ep0->dummy_packets_Q, pkt->data);
+ cq_put(&usb->ep0->dummy_packets_Q, pkt->data);
}
recycle_frame(usb, pkt);
@@ -213,7 +213,7 @@
}
/* update frame object fields before transmitting */
- pkt = cq_get(usb->ep0->empty_frame_Q);
+ pkt = cq_get(&usb->ep0->empty_frame_Q);
if (!pkt) {
fhci_dbg(usb->fhci, "there is no empty frame\n");
return -1;
@@ -222,7 +222,7 @@
pkt->info = 0;
if (data == NULL) {
- data = cq_get(usb->ep0->dummy_packets_Q);
+ data = cq_get(&usb->ep0->dummy_packets_Q);
BUG_ON(!data);
pkt->info = PKT_DUMMY_PACKET;
}
@@ -246,7 +246,7 @@
list_del_init(&td->frame_lh);
td->status = USB_TD_OK;
if (pkt->info & PKT_DUMMY_PACKET)
- cq_put(usb->ep0->dummy_packets_Q, pkt->data);
+ cq_put(&usb->ep0->dummy_packets_Q, pkt->data);
recycle_frame(usb, pkt);
usb->actual_frame->total_bytes -= (len + PROTOCOL_OVERHEAD);
fhci_err(usb->fhci, "host transaction failed\n");