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kfifo: move struct kfifo in place

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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>
This commit is contained in:
Stefani Seibold
2009-12-21 14:37:26 -08:00
committed by Linus Torvalds
parent 2ec91eec47
commit 4546548789
24 changed files with 238 additions and 259 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
drivers/scsi/libiscsi_tcp.c
View File

@@ -445,15 +445,15 @@ void iscsi_tcp_cleanup_task(struct iscsi_task *task)
return;
/* flush task's r2t queues */
while (__kfifo_get(tcp_task->r2tqueue, (void*)&r2t, sizeof(void*))) {
__kfifo_put(tcp_task->r2tpool.queue, (void*)&r2t,
while (__kfifo_get(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*))) {
__kfifo_put(&tcp_task->r2tpool.queue, (void*)&r2t,
sizeof(void*));
ISCSI_DBG_TCP(task->conn, "pending r2t dropped\n");
}
r2t = tcp_task->r2t;
if (r2t != NULL) {
__kfifo_put(tcp_task->r2tpool.queue, (void*)&r2t,
__kfifo_put(&tcp_task->r2tpool.queue, (void*)&r2t,
sizeof(void*));
tcp_task->r2t = NULL;
}
@@ -541,7 +541,7 @@ static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
return 0;
}
rc = __kfifo_get(tcp_task->r2tpool.queue, (void*)&r2t, sizeof(void*));
rc = __kfifo_get(&tcp_task->r2tpool.queue, (void*)&r2t, sizeof(void*));
if (!rc) {
iscsi_conn_printk(KERN_ERR, conn, "Could not allocate R2T. "
"Target has sent more R2Ts than it "
@@ -554,7 +554,7 @@ static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
if (r2t->data_length == 0) {
iscsi_conn_printk(KERN_ERR, conn,
"invalid R2T with zero data len\n");
__kfifo_put(tcp_task->r2tpool.queue, (void*)&r2t,
__kfifo_put(&tcp_task->r2tpool.queue, (void*)&r2t,
sizeof(void*));
return ISCSI_ERR_DATALEN;
}
@@ -570,7 +570,7 @@ static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
"invalid R2T with data len %u at offset %u "
"and total length %d\n", r2t->data_length,
r2t->data_offset, scsi_out(task->sc)->length);
__kfifo_put(tcp_task->r2tpool.queue, (void*)&r2t,
__kfifo_put(&tcp_task->r2tpool.queue, (void*)&r2t,
sizeof(void*));
return ISCSI_ERR_DATALEN;
}
@@ -580,7 +580,7 @@ static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
r2t->sent = 0;
tcp_task->exp_datasn = r2tsn + 1;
__kfifo_put(tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
__kfifo_put(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
conn->r2t_pdus_cnt++;
iscsi_requeue_task(task);
@@ -951,7 +951,7 @@ int iscsi_tcp_task_init(struct iscsi_task *task)
return conn->session->tt->init_pdu(task, 0, task->data_count);
}
BUG_ON(__kfifo_len(tcp_task->r2tqueue));
BUG_ON(__kfifo_len(&tcp_task->r2tqueue));
tcp_task->exp_datasn = 0;
/* Prepare PDU, optionally w/ immediate data */
@@ -982,7 +982,7 @@ static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
if (r2t->data_length <= r2t->sent) {
ISCSI_DBG_TCP(task->conn,
" done with r2t %p\n", r2t);
__kfifo_put(tcp_task->r2tpool.queue,
__kfifo_put(&tcp_task->r2tpool.queue,
(void *)&tcp_task->r2t,
sizeof(void *));
tcp_task->r2t = r2t = NULL;
@@ -990,7 +990,7 @@ static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
}
if (r2t == NULL) {
__kfifo_get(tcp_task->r2tqueue,
__kfifo_get(&tcp_task->r2tqueue,
(void *)&tcp_task->r2t, sizeof(void *));
r2t = tcp_task->r2t;
}
@@ -1127,9 +1127,8 @@ int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session)
}
/* R2T xmit queue */
tcp_task->r2tqueue = kfifo_alloc(
session->max_r2t * 4 * sizeof(void*), GFP_KERNEL, NULL);
if (tcp_task->r2tqueue == ERR_PTR(-ENOMEM)) {
if (kfifo_alloc(&tcp_task->r2tqueue,
session->max_r2t * 4 * sizeof(void*), GFP_KERNEL, NULL)) {
iscsi_pool_free(&tcp_task->r2tpool);
goto r2t_alloc_fail;
}
@@ -1142,7 +1141,7 @@ r2t_alloc_fail:
struct iscsi_task *task = session->cmds[i];
struct iscsi_tcp_task *tcp_task = task->dd_data;
kfifo_free(tcp_task->r2tqueue);
kfifo_free(&tcp_task->r2tqueue);
iscsi_pool_free(&tcp_task->r2tpool);
}
return -ENOMEM;
@@ -1157,7 +1156,7 @@ void iscsi_tcp_r2tpool_free(struct iscsi_session *session)
struct iscsi_task *task = session->cmds[i];
struct iscsi_tcp_task *tcp_task = task->dd_data;
kfifo_free(tcp_task->r2tqueue);
kfifo_free(&tcp_task->r2tqueue);
iscsi_pool_free(&tcp_task->r2tpool);
}
}