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/libiscsi.c | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) (limited to 'drivers/scsi/libiscsi.c') diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c index b7689f3..cf0aa7e 100644 --- a/drivers/scsi/libiscsi.c +++ b/drivers/scsi/libiscsi.c @@ -517,7 +517,7 @@ static void iscsi_free_task(struct iscsi_task *task) if (conn->login_task == task) return; - __kfifo_put(session->cmdpool.queue, (void*)&task, sizeof(void*)); + __kfifo_put(&session->cmdpool.queue, (void*)&task, sizeof(void*)); if (sc) { task->sc = NULL; @@ -737,7 +737,7 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr, BUG_ON(conn->c_stage == ISCSI_CONN_INITIAL_STAGE); BUG_ON(conn->c_stage == ISCSI_CONN_STOPPED); - if (!__kfifo_get(session->cmdpool.queue, + if (!__kfifo_get(&session->cmdpool.queue, (void*)&task, sizeof(void*))) return NULL; } @@ -1567,7 +1567,7 @@ static inline struct iscsi_task *iscsi_alloc_task(struct iscsi_conn *conn, { struct iscsi_task *task; - if (!__kfifo_get(conn->session->cmdpool.queue, + if (!__kfifo_get(&conn->session->cmdpool.queue, (void *) &task, sizeof(void *))) return NULL; @@ -2461,12 +2461,7 @@ iscsi_pool_init(struct iscsi_pool *q, int max, void ***items, int item_size) if (q->pool == NULL) return -ENOMEM; - q->queue = kfifo_init((void*)q->pool, max * sizeof(void*), - GFP_KERNEL, NULL); - if (IS_ERR(q->queue)) { - q->queue = NULL; - goto enomem; - } + kfifo_init(&q->queue, (void*)q->pool, max * sizeof(void*), NULL); for (i = 0; i < max; i++) { q->pool[i] = kzalloc(item_size, GFP_KERNEL); @@ -2474,7 +2469,7 @@ iscsi_pool_init(struct iscsi_pool *q, int max, void ***items, int item_size) q->max = i; goto enomem; } - __kfifo_put(q->queue, (void*)&q->pool[i], sizeof(void*)); + __kfifo_put(&q->queue, (void*)&q->pool[i], sizeof(void*)); } if (items) { @@ -2497,7 +2492,6 @@ void iscsi_pool_free(struct iscsi_pool *q) for (i = 0; i < q->max; i++) kfree(q->pool[i]); kfree(q->pool); - kfree(q->queue); } EXPORT_SYMBOL_GPL(iscsi_pool_free); @@ -2825,7 +2819,7 @@ iscsi_conn_setup(struct iscsi_cls_session *cls_session, int dd_size, /* allocate login_task used for the login/text sequences */ spin_lock_bh(&session->lock); - if (!__kfifo_get(session->cmdpool.queue, + if (!__kfifo_get(&session->cmdpool.queue, (void*)&conn->login_task, sizeof(void*))) { spin_unlock_bh(&session->lock); @@ -2845,7 +2839,7 @@ iscsi_conn_setup(struct iscsi_cls_session *cls_session, int dd_size, return cls_conn; login_task_data_alloc_fail: - __kfifo_put(session->cmdpool.queue, (void*)&conn->login_task, + __kfifo_put(&session->cmdpool.queue, (void*)&conn->login_task, sizeof(void*)); login_task_alloc_fail: iscsi_destroy_conn(cls_conn); @@ -2908,7 +2902,7 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn) free_pages((unsigned long) conn->data, get_order(ISCSI_DEF_MAX_RECV_SEG_LEN)); kfree(conn->persistent_address); - __kfifo_put(session->cmdpool.queue, (void*)&conn->login_task, + __kfifo_put(&session->cmdpool.queue, (void*)&conn->login_task, sizeof(void*)); if (session->leadconn == conn) session->leadconn = NULL; -- cgit v1.1