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linux-next/include/scsi/libiscsi_tcp.h
Stefani Seibold 4546548789 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>
2009-12-22 14:17:55 -08:00

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/*
* iSCSI over TCP/IP Data-Path lib
*
* Copyright (C) 2008 Mike Christie
* Copyright (C) 2008 Red Hat, Inc. All rights reserved.
* maintained by open-iscsi@googlegroups.com
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* See the file COPYING included with this distribution for more details.
*/
#ifndef LIBISCSI_TCP_H
#define LIBISCSI_TCP_H
#include <scsi/libiscsi.h>
struct iscsi_tcp_conn;
struct iscsi_segment;
struct sk_buff;
struct hash_desc;
typedef int iscsi_segment_done_fn_t(struct iscsi_tcp_conn *,
struct iscsi_segment *);
struct iscsi_segment {
unsigned char *data;
unsigned int size;
unsigned int copied;
unsigned int total_size;
unsigned int total_copied;
struct hash_desc *hash;
unsigned char padbuf[ISCSI_PAD_LEN];
unsigned char recv_digest[ISCSI_DIGEST_SIZE];
unsigned char digest[ISCSI_DIGEST_SIZE];
unsigned int digest_len;
struct scatterlist *sg;
void *sg_mapped;
unsigned int sg_offset;
iscsi_segment_done_fn_t *done;
};
/* Socket connection recieve helper */
struct iscsi_tcp_recv {
struct iscsi_hdr *hdr;
struct iscsi_segment segment;
/* Allocate buffer for BHS + AHS */
uint32_t hdr_buf[64];
/* copied and flipped values */
int datalen;
};
struct iscsi_tcp_conn {
struct iscsi_conn *iscsi_conn;
void *dd_data;
int stop_stage; /* conn_stop() flag: *
* stop to recover, *
* stop to terminate */
/* control data */
struct iscsi_tcp_recv in; /* TCP receive context */
/* CRC32C (Rx) LLD should set this is they do not offload */
struct hash_desc *rx_hash;
};
struct iscsi_tcp_task {
uint32_t exp_datasn; /* expected target's R2TSN/DataSN */
int data_offset;
struct iscsi_r2t_info *r2t; /* in progress solict R2T */
struct iscsi_pool r2tpool;
struct kfifo r2tqueue;
void *dd_data;
};
enum {
ISCSI_TCP_SEGMENT_DONE, /* curr seg has been processed */
ISCSI_TCP_SKB_DONE, /* skb is out of data */
ISCSI_TCP_CONN_ERR, /* iscsi layer has fired a conn err */
ISCSI_TCP_SUSPENDED, /* conn is suspended */
};
extern void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn);
extern int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
unsigned int offset, bool offloaded, int *status);
extern void iscsi_tcp_cleanup_task(struct iscsi_task *task);
extern int iscsi_tcp_task_init(struct iscsi_task *task);
extern int iscsi_tcp_task_xmit(struct iscsi_task *task);
/* segment helpers */
extern int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn);
extern int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
struct iscsi_segment *segment, int recv,
unsigned copied);
extern void iscsi_tcp_segment_unmap(struct iscsi_segment *segment);
extern void iscsi_segment_init_linear(struct iscsi_segment *segment,
void *data, size_t size,
iscsi_segment_done_fn_t *done,
struct hash_desc *hash);
extern int
iscsi_segment_seek_sg(struct iscsi_segment *segment,
struct scatterlist *sg_list, unsigned int sg_count,
unsigned int offset, size_t size,
iscsi_segment_done_fn_t *done, struct hash_desc *hash);
/* digest helpers */
extern void iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr,
size_t hdrlen,
unsigned char digest[ISCSI_DIGEST_SIZE]);
extern struct iscsi_cls_conn *
iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
uint32_t conn_idx);
extern void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn);
/* misc helpers */
extern int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session);
extern void iscsi_tcp_r2tpool_free(struct iscsi_session *session);
extern void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
struct iscsi_stats *stats);
#endif /* LIBISCSI_TCP_H */
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