blob: 8ac96f57438896dea03fedad7e55d4ffb9ff3f11 (
plain)
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
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
|
/*
* Wrapper functions for accessing the file_struct fd array.
*/
#ifndef __LINUX_FILE_H
#define __LINUX_FILE_H
extern void _fput(struct file *);
static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
{
struct file * file = NULL;
if (fd < files->max_fds)
file = files->fd[fd];
return file;
}
/*
* Check whether the specified fd has an open file.
*/
static inline struct file * fcheck(unsigned int fd)
{
struct file * file = NULL;
struct files_struct *files = current->files;
if (fd < files->max_fds)
file = files->fd[fd];
return file;
}
static inline struct file * frip(struct files_struct *files, unsigned int fd)
{
struct file * file = NULL;
if (fd < files->max_fds)
file = xchg(&files->fd[fd], NULL);
return file;
}
static inline struct file * fget(unsigned int fd)
{
struct file * file = NULL;
struct files_struct *files = current->files;
read_lock(&files->file_lock);
file = fcheck(fd);
if (file)
get_file(file);
read_unlock(&files->file_lock);
return file;
}
/*
* 23/12/1998 Marcin Dalecki <dalecki@cs.net.pl>:
*
* Since those functions where calling other functions, it was completely
* bogus to make them all "extern inline".
*
* The removal of this pseudo optimization saved me scandalous:
*
* 3756 (i386 arch)
*
* precious bytes from my kernel, even without counting all the code compiled
* as module!
*
* I suspect there are many other similar "optimizations" across the
* kernel...
*/
static inline void fput(struct file * file)
{
if (atomic_dec_and_test(&file->f_count))
_fput(file);
}
extern void put_filp(struct file *);
/*
* Install a file pointer in the fd array.
*
* The VFS is full of places where we drop the files lock between
* setting the open_fds bitmap and installing the file in the file
* array. At any such point, we are vulnerable to a dup2() race
* installing a file in the array before us. We need to detect this and
* fput() the struct file we are about to overwrite in this case.
*/
static inline void fd_install(unsigned int fd, struct file * file)
{
struct files_struct *files = current->files;
struct file * result;
write_lock(&files->file_lock);
result = xchg(&files->fd[fd], file);
write_unlock(&files->file_lock);
if (result)
fput(result);
}
void put_files_struct(struct files_struct *fs);
#endif /* __LINUX_FILE_H */
|
