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author | Stefani Seibold <stefani@seibold.net> | 2009-12-21 14:37:26 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-22 14:17:55 -0800 |
commit | 45465487897a1c6d508b14b904dc5777f7ec7e04 (patch) | |
tree | 935c8dae68dc793ff2f795d57cf027531475cd53 /drivers/scsi/libiscsi.c | |
parent | 2ec91eec47f713e3d158ba5b28a24a85a2cf3650 (diff) | |
download | kernel_samsung_aries-45465487897a1c6d508b14b904dc5777f7ec7e04.zip kernel_samsung_aries-45465487897a1c6d508b14b904dc5777f7ec7e04.tar.gz kernel_samsung_aries-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.c | 22 |
1 files changed, 8 insertions, 14 deletions
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; |