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4546548789
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>
134 lines
4.2 KiB
C
134 lines
4.2 KiB
C
/*
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* iSCSI over TCP/IP Data-Path lib
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*
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* Copyright (C) 2008 Mike Christie
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* Copyright (C) 2008 Red Hat, Inc. All rights reserved.
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* maintained by open-iscsi@googlegroups.com
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published
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* by the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* See the file COPYING included with this distribution for more details.
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*/
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#ifndef LIBISCSI_TCP_H
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#define LIBISCSI_TCP_H
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#include <scsi/libiscsi.h>
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struct iscsi_tcp_conn;
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struct iscsi_segment;
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struct sk_buff;
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struct hash_desc;
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typedef int iscsi_segment_done_fn_t(struct iscsi_tcp_conn *,
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struct iscsi_segment *);
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struct iscsi_segment {
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unsigned char *data;
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unsigned int size;
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unsigned int copied;
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unsigned int total_size;
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unsigned int total_copied;
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struct hash_desc *hash;
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unsigned char padbuf[ISCSI_PAD_LEN];
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unsigned char recv_digest[ISCSI_DIGEST_SIZE];
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unsigned char digest[ISCSI_DIGEST_SIZE];
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unsigned int digest_len;
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struct scatterlist *sg;
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void *sg_mapped;
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unsigned int sg_offset;
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iscsi_segment_done_fn_t *done;
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};
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/* Socket connection recieve helper */
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struct iscsi_tcp_recv {
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struct iscsi_hdr *hdr;
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struct iscsi_segment segment;
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/* Allocate buffer for BHS + AHS */
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uint32_t hdr_buf[64];
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/* copied and flipped values */
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int datalen;
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};
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struct iscsi_tcp_conn {
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struct iscsi_conn *iscsi_conn;
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void *dd_data;
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int stop_stage; /* conn_stop() flag: *
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* stop to recover, *
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* stop to terminate */
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/* control data */
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struct iscsi_tcp_recv in; /* TCP receive context */
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/* CRC32C (Rx) LLD should set this is they do not offload */
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struct hash_desc *rx_hash;
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};
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struct iscsi_tcp_task {
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uint32_t exp_datasn; /* expected target's R2TSN/DataSN */
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int data_offset;
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struct iscsi_r2t_info *r2t; /* in progress solict R2T */
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struct iscsi_pool r2tpool;
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struct kfifo r2tqueue;
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void *dd_data;
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};
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enum {
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ISCSI_TCP_SEGMENT_DONE, /* curr seg has been processed */
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ISCSI_TCP_SKB_DONE, /* skb is out of data */
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ISCSI_TCP_CONN_ERR, /* iscsi layer has fired a conn err */
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ISCSI_TCP_SUSPENDED, /* conn is suspended */
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};
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extern void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn);
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extern int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
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unsigned int offset, bool offloaded, int *status);
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extern void iscsi_tcp_cleanup_task(struct iscsi_task *task);
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extern int iscsi_tcp_task_init(struct iscsi_task *task);
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extern int iscsi_tcp_task_xmit(struct iscsi_task *task);
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/* segment helpers */
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extern int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn);
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extern int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
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struct iscsi_segment *segment, int recv,
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unsigned copied);
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extern void iscsi_tcp_segment_unmap(struct iscsi_segment *segment);
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extern void iscsi_segment_init_linear(struct iscsi_segment *segment,
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void *data, size_t size,
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iscsi_segment_done_fn_t *done,
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struct hash_desc *hash);
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extern int
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iscsi_segment_seek_sg(struct iscsi_segment *segment,
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struct scatterlist *sg_list, unsigned int sg_count,
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unsigned int offset, size_t size,
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iscsi_segment_done_fn_t *done, struct hash_desc *hash);
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/* digest helpers */
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extern void iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr,
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size_t hdrlen,
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unsigned char digest[ISCSI_DIGEST_SIZE]);
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extern struct iscsi_cls_conn *
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iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
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uint32_t conn_idx);
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extern void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn);
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/* misc helpers */
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extern int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session);
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extern void iscsi_tcp_r2tpool_free(struct iscsi_session *session);
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extern void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
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struct iscsi_stats *stats);
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#endif /* LIBISCSI_TCP_H */
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