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
|
// this is a GCC extension
#ifdef __GNUC__
static inline __attribute__((always_inline)) _Bool
__is_kfree_rcu_offset(unsigned long offset)
{
return offset < 4096;
}
static inline __attribute__((always_inline)) void
kfree_rcu(unsigned long offset)
{
// immediate use of a constant as argument to __builtin_constant_p
((void)sizeof(char[1 - 2 * !!(!__builtin_constant_p(offset))]));
// inlining required to turn the array size into a compile-time constant
((void)sizeof(char[1 - 2 * !!(!__is_kfree_rcu_offset(offset))]));
}
static inline __attribute__((always_inline)) void unused(unsigned long offset)
{
// this would not be constant as it's never used, the front-end needs to
// discard it
((void)sizeof(char[1 - 2 * !!(!__builtin_constant_p(offset))]));
}
// unused, but no 'static'
inline __attribute__((__always_inline__)) int also_unused(int _c)
{
return _c;
}
#endif
int main()
{
#ifdef __GNUC__
kfree_rcu(42);
#endif
return 0;
}
|
