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>

1 files changed, 10 insertions, 11 deletions

diff --git a/drivers/char/nozomi.c b/drivers/char/nozomi.c
index d3400b20444f..0f39bec28b45 100644
--- a/drivers/char/nozomi.c
+++ b/drivers/char/nozomi.c
@@ -358,7 +358,7 @@ struct port {
 	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 @@ static int nozomi_read_config_table(struct nozomi *dc)
 		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 @@ static int send_data(enum port_type index, struct nozomi *dc)
 	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 @@ static int receive_flow_control(struct nozomi *dc)
 
 	} 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 @@ static void __devexit nozomi_card_exit(struct pci_dev *pdev)
 	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 @@ static int ntty_write(struct tty_struct *tty, const unsigned char *buffer,
 		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 @@ static int ntty_write_room(struct tty_struct *tty)
 	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 @@ static s32 ntty_chars_in_buffer(struct tty_struct *tty)
 		goto exit_in_buffer;
 	}
 
-	rval = __kfifo_len(port->fifo_ul);
+	rval = __kfifo_len(&port->fifo_ul);
 
 exit_in_buffer:
 	return rval;