From 45465487897a1c6d508b14b904dc5777f7ec7e04 Mon Sep 17 00:00:00 2001 From: Stefani Seibold Date: Mon, 21 Dec 2009 14:37:26 -0800 Subject: 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 Acked-by: Greg Kroah-Hartman Acked-by: Mauro Carvalho Chehab Acked-by: Andi Kleen Acked-by: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/scsi/libsrp.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) (limited to 'drivers/scsi/libsrp.c') diff --git a/drivers/scsi/libsrp.c b/drivers/scsi/libsrp.c index 9ad38e81e34..b1b5e51ca8e 100644 --- a/drivers/scsi/libsrp.c +++ b/drivers/scsi/libsrp.c @@ -58,19 +58,16 @@ static int srp_iu_pool_alloc(struct srp_queue *q, size_t max, goto free_pool; spin_lock_init(&q->lock); - q->queue = kfifo_init((void *) q->pool, max * sizeof(void *), - GFP_KERNEL, &q->lock); - if (IS_ERR(q->queue)) - goto free_item; + kfifo_init(&q->queue, (void *) q->pool, max * sizeof(void *), + &q->lock); for (i = 0, iue = q->items; i < max; i++) { - __kfifo_put(q->queue, (void *) &iue, sizeof(void *)); + __kfifo_put(&q->queue, (void *) &iue, sizeof(void *)); iue->sbuf = ring[i]; iue++; } return 0; -free_item: kfree(q->items); free_pool: kfree(q->pool); @@ -167,7 +164,7 @@ struct iu_entry *srp_iu_get(struct srp_target *target) { struct iu_entry *iue = NULL; - kfifo_get(target->iu_queue.queue, (void *) &iue, sizeof(void *)); + kfifo_get(&target->iu_queue.queue, (void *) &iue, sizeof(void *)); if (!iue) return iue; iue->target = target; @@ -179,7 +176,7 @@ EXPORT_SYMBOL_GPL(srp_iu_get); void srp_iu_put(struct iu_entry *iue) { - kfifo_put(iue->target->iu_queue.queue, (void *) &iue, sizeof(void *)); + kfifo_put(&iue->target->iu_queue.queue, (void *) &iue, sizeof(void *)); } EXPORT_SYMBOL_GPL(srp_iu_put); -- cgit v1.2.3