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/char/nozomi.c b/drivers/char/nozomi.c
index d3400b2..0f39bec 100644
--- a/drivers/char/nozomi.c
+++ b/drivers/char/nozomi.c
@@ -358,7 +358,7 @@
u8 update_flow_control;
struct ctrl_ul ctrl_ul;
struct ctrl_dl ctrl_dl;
- struct kfifo *fifo_ul;
+ struct kfifo fifo_ul;
void __iomem *dl_addr[2];
u32 dl_size[2];
u8 toggle_dl;
@@ -685,8 +685,8 @@
dump_table(dc);
for (i = PORT_MDM; i < MAX_PORT; i++) {
- dc->port[i].fifo_ul =
- kfifo_alloc(FIFO_BUFFER_SIZE_UL, GFP_ATOMIC, NULL);
+ kfifo_alloc(&dc->port[i].fifo_ul,
+ FIFO_BUFFER_SIZE_UL, GFP_ATOMIC, NULL);
memset(&dc->port[i].ctrl_dl, 0, sizeof(struct ctrl_dl));
memset(&dc->port[i].ctrl_ul, 0, sizeof(struct ctrl_ul));
}
@@ -798,7 +798,7 @@
struct tty_struct *tty = tty_port_tty_get(&port->port);
/* Get data from tty and place in buf for now */
- size = __kfifo_get(port->fifo_ul, dc->send_buf,
+ size = __kfifo_get(&port->fifo_ul, dc->send_buf,
ul_size < SEND_BUF_MAX ? ul_size : SEND_BUF_MAX);
if (size == 0) {
@@ -988,11 +988,11 @@
} else if (old_ctrl.CTS == 0 && ctrl_dl.CTS == 1) {
- if (__kfifo_len(dc->port[port].fifo_ul)) {
+ if (__kfifo_len(&dc->port[port].fifo_ul)) {
DBG1("Enable interrupt (0x%04X) on port: %d",
enable_ier, port);
DBG1("Data in buffer [%d], enable transmit! ",
- __kfifo_len(dc->port[port].fifo_ul));
+ __kfifo_len(&dc->port[port].fifo_ul));
enable_transmit_ul(port, dc);
} else {
DBG1("No data in buffer...");
@@ -1536,8 +1536,7 @@
free_irq(pdev->irq, dc);
for (i = 0; i < MAX_PORT; i++)
- if (dc->port[i].fifo_ul)
- kfifo_free(dc->port[i].fifo_ul);
+ kfifo_free(&dc->port[i].fifo_ul);
kfree(dc->send_buf);
@@ -1673,7 +1672,7 @@
goto exit;
}
- rval = __kfifo_put(port->fifo_ul, (unsigned char *)buffer, count);
+ rval = __kfifo_put(&port->fifo_ul, (unsigned char *)buffer, count);
/* notify card */
if (unlikely(dc == NULL)) {
@@ -1721,7 +1720,7 @@
if (!port->port.count)
goto exit;
- room = port->fifo_ul->size - __kfifo_len(port->fifo_ul);
+ room = port->fifo_ul.size - __kfifo_len(&port->fifo_ul);
exit:
mutex_unlock(&port->tty_sem);
@@ -1878,7 +1877,7 @@
goto exit_in_buffer;
}
- rval = __kfifo_len(port->fifo_ul);
+ rval = __kfifo_len(&port->fifo_ul);
exit_in_buffer:
return rval;