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authorStefani Seibold <stefani@seibold.net>2009-12-21 14:37:26 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-22 14:17:55 -0800
commit45465487897a1c6d508b14b904dc5777f7ec7e04 (patch)
tree935c8dae68dc793ff2f795d57cf027531475cd53 /drivers/scsi/libiscsi.c
parent2ec91eec47f713e3d158ba5b28a24a85a2cf3650 (diff)
downloadlinux-45465487897a1c6d508b14b904dc5777f7ec7e04.tar.bz2
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>
Diffstat (limited to 'drivers/scsi/libiscsi.c')
-rw-r--r--drivers/scsi/libiscsi.c22
1 files changed, 8 insertions, 14 deletions
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index b7689f3d05f5..cf0aa7e90be9 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;