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, 29 insertions, 31 deletions

diff --git a/drivers/infiniband/hw/cxgb3/cxio_resource.c b/drivers/infiniband/hw/cxgb3/cxio_resource.c
index bd233c087653..65072bdfc1bf 100644
--- a/drivers/infiniband/hw/cxgb3/cxio_resource.c
+++ b/drivers/infiniband/hw/cxgb3/cxio_resource.c
@@ -39,12 +39,12 @@
 #include "cxio_resource.h"
 #include "cxio_hal.h"
 
-static struct kfifo *rhdl_fifo;
+static struct kfifo rhdl_fifo;
 static spinlock_t rhdl_fifo_lock;
 
 #define RANDOM_SIZE 16
 
-static int __cxio_init_resource_fifo(struct kfifo **fifo,
+static int __cxio_init_resource_fifo(struct kfifo *fifo,
 				   spinlock_t *fifo_lock,
 				   u32 nr, u32 skip_low,
 				   u32 skip_high,
@@ -55,12 +55,11 @@ static int __cxio_init_resource_fifo(struct kfifo **fifo,
 	u32 rarray[16];
 	spin_lock_init(fifo_lock);
 
-	*fifo = kfifo_alloc(nr * sizeof(u32), GFP_KERNEL, fifo_lock);
-	if (IS_ERR(*fifo))
+	if (kfifo_alloc(fifo, nr * sizeof(u32), GFP_KERNEL, fifo_lock))
 		return -ENOMEM;
 
 	for (i = 0; i < skip_low + skip_high; i++)
-		__kfifo_put(*fifo, (unsigned char *) &entry, sizeof(u32));
+		__kfifo_put(fifo, (unsigned char *) &entry, sizeof(u32));
 	if (random) {
 		j = 0;
 		random_bytes = random32();
@@ -72,33 +71,33 @@ static int __cxio_init_resource_fifo(struct kfifo **fifo,
 				random_bytes = random32();
 			}
 			idx = (random_bytes >> (j * 2)) & 0xF;
-			__kfifo_put(*fifo,
+			__kfifo_put(fifo,
 				(unsigned char *) &rarray[idx],
 				sizeof(u32));
 			rarray[idx] = i;
 			j++;
 		}
 		for (i = 0; i < RANDOM_SIZE; i++)
-			__kfifo_put(*fifo,
+			__kfifo_put(fifo,
 				(unsigned char *) &rarray[i],
 				sizeof(u32));
 	} else
 		for (i = skip_low; i < nr - skip_high; i++)
-			__kfifo_put(*fifo, (unsigned char *) &i, sizeof(u32));
+			__kfifo_put(fifo, (unsigned char *) &i, sizeof(u32));
 
 	for (i = 0; i < skip_low + skip_high; i++)
-		kfifo_get(*fifo, (unsigned char *) &entry, sizeof(u32));
+		kfifo_get(fifo, (unsigned char *) &entry, sizeof(u32));
 	return 0;
 }
 
-static int cxio_init_resource_fifo(struct kfifo **fifo, spinlock_t * fifo_lock,
+static int cxio_init_resource_fifo(struct kfifo *fifo, spinlock_t * fifo_lock,
 				   u32 nr, u32 skip_low, u32 skip_high)
 {
 	return (__cxio_init_resource_fifo(fifo, fifo_lock, nr, skip_low,
 					  skip_high, 0));
 }
 
-static int cxio_init_resource_fifo_random(struct kfifo **fifo,
+static int cxio_init_resource_fifo_random(struct kfifo *fifo,
 				   spinlock_t * fifo_lock,
 				   u32 nr, u32 skip_low, u32 skip_high)
 {
@@ -113,15 +112,14 @@ static int cxio_init_qpid_fifo(struct cxio_rdev *rdev_p)
 
 	spin_lock_init(&rdev_p->rscp->qpid_fifo_lock);
 
-	rdev_p->rscp->qpid_fifo = kfifo_alloc(T3_MAX_NUM_QP * sizeof(u32),
+	if (kfifo_alloc(&rdev_p->rscp->qpid_fifo, T3_MAX_NUM_QP * sizeof(u32),
 					      GFP_KERNEL,
-					      &rdev_p->rscp->qpid_fifo_lock);
-	if (IS_ERR(rdev_p->rscp->qpid_fifo))
+					      &rdev_p->rscp->qpid_fifo_lock))
 		return -ENOMEM;
 
 	for (i = 16; i < T3_MAX_NUM_QP; i++)
 		if (!(i & rdev_p->qpmask))
-			__kfifo_put(rdev_p->rscp->qpid_fifo,
+			__kfifo_put(&rdev_p->rscp->qpid_fifo,
 				    (unsigned char *) &i, sizeof(u32));
 	return 0;
 }
@@ -134,7 +132,7 @@ int cxio_hal_init_rhdl_resource(u32 nr_rhdl)
 
 void cxio_hal_destroy_rhdl_resource(void)
 {
-	kfifo_free(rhdl_fifo);
+	kfifo_free(&rhdl_fifo);
 }
 
 /* nr_* must be power of 2 */
@@ -167,11 +165,11 @@ int cxio_hal_init_resource(struct cxio_rdev *rdev_p,
 		goto pdid_err;
 	return 0;
 pdid_err:
-	kfifo_free(rscp->cqid_fifo);
+	kfifo_free(&rscp->cqid_fifo);
 cqid_err:
-	kfifo_free(rscp->qpid_fifo);
+	kfifo_free(&rscp->qpid_fifo);
 qpid_err:
-	kfifo_free(rscp->tpt_fifo);
+	kfifo_free(&rscp->tpt_fifo);
 tpt_err:
 	return -ENOMEM;
 }
@@ -195,17 +193,17 @@ static void cxio_hal_put_resource(struct kfifo *fifo, u32 entry)
 
 u32 cxio_hal_get_stag(struct cxio_hal_resource *rscp)
 {
-	return cxio_hal_get_resource(rscp->tpt_fifo);
+	return cxio_hal_get_resource(&rscp->tpt_fifo);
 }
 
 void cxio_hal_put_stag(struct cxio_hal_resource *rscp, u32 stag)
 {
-	cxio_hal_put_resource(rscp->tpt_fifo, stag);
+	cxio_hal_put_resource(&rscp->tpt_fifo, stag);
 }
 
 u32 cxio_hal_get_qpid(struct cxio_hal_resource *rscp)
 {
-	u32 qpid = cxio_hal_get_resource(rscp->qpid_fifo);
+	u32 qpid = cxio_hal_get_resource(&rscp->qpid_fifo);
 	PDBG("%s qpid 0x%x\n", __func__, qpid);
 	return qpid;
 }
@@ -213,35 +211,35 @@ u32 cxio_hal_get_qpid(struct cxio_hal_resource *rscp)
 void cxio_hal_put_qpid(struct cxio_hal_resource *rscp, u32 qpid)
 {
 	PDBG("%s qpid 0x%x\n", __func__, qpid);
-	cxio_hal_put_resource(rscp->qpid_fifo, qpid);
+	cxio_hal_put_resource(&rscp->qpid_fifo, qpid);
 }
 
 u32 cxio_hal_get_cqid(struct cxio_hal_resource *rscp)
 {
-	return cxio_hal_get_resource(rscp->cqid_fifo);
+	return cxio_hal_get_resource(&rscp->cqid_fifo);
 }
 
 void cxio_hal_put_cqid(struct cxio_hal_resource *rscp, u32 cqid)
 {
-	cxio_hal_put_resource(rscp->cqid_fifo, cqid);
+	cxio_hal_put_resource(&rscp->cqid_fifo, cqid);
 }
 
 u32 cxio_hal_get_pdid(struct cxio_hal_resource *rscp)
 {
-	return cxio_hal_get_resource(rscp->pdid_fifo);
+	return cxio_hal_get_resource(&rscp->pdid_fifo);
 }
 
 void cxio_hal_put_pdid(struct cxio_hal_resource *rscp, u32 pdid)
 {
-	cxio_hal_put_resource(rscp->pdid_fifo, pdid);
+	cxio_hal_put_resource(&rscp->pdid_fifo, pdid);
 }
 
 void cxio_hal_destroy_resource(struct cxio_hal_resource *rscp)
 {
-	kfifo_free(rscp->tpt_fifo);
-	kfifo_free(rscp->cqid_fifo);
-	kfifo_free(rscp->qpid_fifo);
-	kfifo_free(rscp->pdid_fifo);
+	kfifo_free(&rscp->tpt_fifo);
+	kfifo_free(&rscp->cqid_fifo);
+	kfifo_free(&rscp->qpid_fifo);
+	kfifo_free(&rscp->pdid_fifo);
 	kfree(rscp);
 }