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-tds.c b/drivers/usb/host/fhci-tds.c
index b403322..d224ab4 100644
--- a/drivers/usb/host/fhci-tds.c
+++ b/drivers/usb/host/fhci-tds.c
@@ -106,33 +106,33 @@
cpm_muram_free(cpm_muram_offset(ep->td_base));
if (ep->conf_frame_Q) {
- size = cq_howmany(ep->conf_frame_Q);
+ size = cq_howmany(&ep->conf_frame_Q);
for (; size; size--) {
- struct packet *pkt = cq_get(ep->conf_frame_Q);
+ struct packet *pkt = cq_get(&ep->conf_frame_Q);
kfree(pkt);
}
- cq_delete(ep->conf_frame_Q);
+ cq_delete(&ep->conf_frame_Q);
}
if (ep->empty_frame_Q) {
- size = cq_howmany(ep->empty_frame_Q);
+ size = cq_howmany(&ep->empty_frame_Q);
for (; size; size--) {
- struct packet *pkt = cq_get(ep->empty_frame_Q);
+ struct packet *pkt = cq_get(&ep->empty_frame_Q);
kfree(pkt);
}
- cq_delete(ep->empty_frame_Q);
+ cq_delete(&ep->empty_frame_Q);
}
if (ep->dummy_packets_Q) {
- size = cq_howmany(ep->dummy_packets_Q);
+ size = cq_howmany(&ep->dummy_packets_Q);
for (; size; size--) {
- u8 *buff = cq_get(ep->dummy_packets_Q);
+ u8 *buff = cq_get(&ep->dummy_packets_Q);
kfree(buff);
}
- cq_delete(ep->dummy_packets_Q);
+ cq_delete(&ep->dummy_packets_Q);
}
kfree(ep);
@@ -175,10 +175,9 @@
ep->td_base = cpm_muram_addr(ep_offset);
/* zero all queue pointers */
- ep->conf_frame_Q = cq_new(ring_len + 2);
- ep->empty_frame_Q = cq_new(ring_len + 2);
- ep->dummy_packets_Q = cq_new(ring_len + 2);
- if (!ep->conf_frame_Q || !ep->empty_frame_Q || !ep->dummy_packets_Q) {
+ if (cq_new(&ep->conf_frame_Q, ring_len + 2) ||
+ cq_new(&ep->empty_frame_Q, ring_len + 2) ||
+ cq_new(&ep->dummy_packets_Q, ring_len + 2)) {
err_for = "frame_queues";
goto err;
}
@@ -199,8 +198,8 @@
err_for = "buffer";
goto err;
}
- cq_put(ep->empty_frame_Q, pkt);
- cq_put(ep->dummy_packets_Q, buff);
+ cq_put(&ep->empty_frame_Q, pkt);
+ cq_put(&ep->dummy_packets_Q, buff);
}
/* we put the endpoint parameter RAM right behind the TD ring */
@@ -319,7 +318,7 @@
if ((buf == DUMMY2_BD_BUFFER) && !(td_status & ~TD_W))
continue;
- pkt = cq_get(ep->conf_frame_Q);
+ pkt = cq_get(&ep->conf_frame_Q);
if (!pkt)
fhci_err(usb->fhci, "no frame to confirm\n");
@@ -460,9 +459,9 @@
out_be16(&td->length, pkt->len);
/* put the frame to the confirmation queue */
- cq_put(ep->conf_frame_Q, pkt);
+ cq_put(&ep->conf_frame_Q, pkt);
- if (cq_howmany(ep->conf_frame_Q) == 1)
+ if (cq_howmany(&ep->conf_frame_Q) == 1)
out_8(&usb->fhci->regs->usb_comm, USB_CMD_STR_FIFO);
return 0;