1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
#ifndef _LINUX_PIPE_FS_I_H
#define _LINUX_PIPE_FS_I_H
#define PIPEFS_MAGIC 0x50495045
#define PIPE_BUFFERS (16)
#define PIPE_BUF_FLAG_LRU 0x01 /* page is on the LRU */
#define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */
#define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */
struct pipe_buffer {
struct page *page;
unsigned int offset, len;
const struct pipe_buf_operations *ops;
unsigned int flags;
unsigned long private;
};
struct pipe_inode_info {
wait_queue_head_t wait;
unsigned int nrbufs, curbuf;
struct page *tmp_page;
unsigned int readers;
unsigned int writers;
unsigned int waiting_writers;
unsigned int r_counter;
unsigned int w_counter;
struct fasync_struct *fasync_readers;
struct fasync_struct *fasync_writers;
struct inode *inode;
struct pipe_buffer bufs[PIPE_BUFFERS];
};
/*
* Note on the nesting of these functions:
*
* ->pin()
* ->steal()
* ...
* ->map()
* ...
* ->unmap()
*
* That is, ->map() must be called on a pinned buffer, same goes for ->steal().
*/
struct pipe_buf_operations {
int can_merge;
void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int);
void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);
int (*pin)(struct pipe_inode_info *, struct pipe_buffer *);
void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
};
/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
#define PIPE_SIZE PAGE_SIZE
/* Drop the inode semaphore and wait for a pipe event, atomically */
void pipe_wait(struct pipe_inode_info *pipe);
struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
void free_pipe_info(struct inode * inode);
void __free_pipe_info(struct pipe_inode_info *);
/* Generic pipe buffer ops functions */
void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int);
void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
int generic_pipe_buf_pin(struct pipe_inode_info *, struct pipe_buffer *);
int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
#endif
|
