x86, io-apic: define names for redirection table entry fields
[linux-2.6] / include / asm-x86 / mutex_64.h
1 /*
2  * Assembly implementation of the mutex fastpath, based on atomic
3  * decrement/increment.
4  *
5  * started by Ingo Molnar:
6  *
7  *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
8  */
9 #ifndef _ASM_MUTEX_H
10 #define _ASM_MUTEX_H
11
12 /**
13  * __mutex_fastpath_lock - decrement and call function if negative
14  * @v: pointer of type atomic_t
15  * @fail_fn: function to call if the result is negative
16  *
17  * Atomically decrements @v and calls <fail_fn> if the result is negative.
18  */
19 #define __mutex_fastpath_lock(v, fail_fn)                       \
20 do {                                                            \
21         unsigned long dummy;                                    \
22                                                                 \
23         typecheck(atomic_t *, v);                               \
24         typecheck_fn(void (*)(atomic_t *), fail_fn);            \
25                                                                 \
26         asm volatile(LOCK_PREFIX "   decl (%%rdi)\n"            \
27                      "   jns 1f         \n"                     \
28                      "   call " #fail_fn "\n"                   \
29                      "1:"                                       \
30                      : "=D" (dummy)                             \
31                      : "D" (v)                                  \
32                      : "rax", "rsi", "rdx", "rcx",              \
33                        "r8", "r9", "r10", "r11", "memory");     \
34 } while (0)
35
36 /**
37  *  __mutex_fastpath_lock_retval - try to take the lock by moving the count
38  *                                 from 1 to a 0 value
39  *  @count: pointer of type atomic_t
40  *  @fail_fn: function to call if the original value was not 1
41  *
42  * Change the count from 1 to a value lower than 1, and call <fail_fn> if
43  * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
44  * or anything the slow path function returns
45  */
46 static inline int __mutex_fastpath_lock_retval(atomic_t *count,
47                                                int (*fail_fn)(atomic_t *))
48 {
49         if (unlikely(atomic_dec_return(count) < 0))
50                 return fail_fn(count);
51         else
52                 return 0;
53 }
54
55 /**
56  * __mutex_fastpath_unlock - increment and call function if nonpositive
57  * @v: pointer of type atomic_t
58  * @fail_fn: function to call if the result is nonpositive
59  *
60  * Atomically increments @v and calls <fail_fn> if the result is nonpositive.
61  */
62 #define __mutex_fastpath_unlock(v, fail_fn)                     \
63 do {                                                            \
64         unsigned long dummy;                                    \
65                                                                 \
66         typecheck(atomic_t *, v);                               \
67         typecheck_fn(void (*)(atomic_t *), fail_fn);            \
68                                                                 \
69         asm volatile(LOCK_PREFIX "   incl (%%rdi)\n"            \
70                      "   jg 1f\n"                               \
71                      "   call " #fail_fn "\n"                   \
72                      "1:"                                       \
73                      : "=D" (dummy)                             \
74                      : "D" (v)                                  \
75                      : "rax", "rsi", "rdx", "rcx",              \
76                        "r8", "r9", "r10", "r11", "memory");     \
77 } while (0)
78
79 #define __mutex_slowpath_needs_to_unlock()      1
80
81 /**
82  * __mutex_fastpath_trylock - try to acquire the mutex, without waiting
83  *
84  *  @count: pointer of type atomic_t
85  *  @fail_fn: fallback function
86  *
87  * Change the count from 1 to 0 and return 1 (success), or return 0 (failure)
88  * if it wasn't 1 originally. [the fallback function is never used on
89  * x86_64, because all x86_64 CPUs have a CMPXCHG instruction.]
90  */
91 static inline int __mutex_fastpath_trylock(atomic_t *count,
92                                            int (*fail_fn)(atomic_t *))
93 {
94         if (likely(atomic_cmpxchg(count, 1, 0) == 1))
95                 return 1;
96         else
97                 return 0;
98 }
99
100 #endif