include/asm-i386/atomic.h

   1 #ifndef __ARCH_I386_ATOMIC__
   2 #define __ARCH_I386_ATOMIC__
   3
   4 #include <linux/compiler.h>
   5 #include <asm/processor.h>
   6
   7 /*
   8  * Atomic operations that C can't guarantee us.  Useful for
   9  * resource counting etc..
  10  */
  11
  12 /*
  13  * Make sure gcc doesn't try to be clever and move things around
  14  * on us. We need to use _exactly_ the address the user gave us,
  15  * not some alias that contains the same information.
  16  */
  17 typedef struct { int counter; } atomic_t;
  18
  19 #define ATOMIC_INIT(i)  { (i) }
  20
  21 /**
  22  * atomic_read - read atomic variable
  23  * @v: pointer of type atomic_t
  24  *
  25  * Atomically reads the value of @v.
  26  */
  27 #define atomic_read(v)          ((v)->counter)
  28
  29 /**
  30  * atomic_set - set atomic variable
  31  * @v: pointer of type atomic_t
  32  * @i: required value
  33  *
  34  * Atomically sets the value of @v to @i.
  35  */
  36 #define atomic_set(v,i)         (((v)->counter) = (i))
  37
  38 /**
  39  * atomic_add - add integer to atomic variable
  40  * @i: integer value to add
  41  * @v: pointer of type atomic_t
  42  *
  43  * Atomically adds @i to @v.
  44  */
  45 static __inline__ void atomic_add(int i, atomic_t *v)
  46 {
  47         __asm__ __volatile__(
  48                 LOCK_PREFIX "addl %1,%0"
  49                 :"+m" (v->counter)
  50                 :"ir" (i));
  51 }
  52
  53 /**
  54  * atomic_sub - subtract the atomic variable
  55  * @i: integer value to subtract
  56  * @v: pointer of type atomic_t
  57  *
  58  * Atomically subtracts @i from @v.
  59  */
  60 static __inline__ void atomic_sub(int i, atomic_t *v)
  61 {
  62         __asm__ __volatile__(
  63                 LOCK_PREFIX "subl %1,%0"
  64                 :"+m" (v->counter)
  65                 :"ir" (i));
  66 }
  67
  68 /**
  69  * atomic_sub_and_test - subtract value from variable and test result
  70  * @i: integer value to subtract
  71  * @v: pointer of type atomic_t
  72  *
  73  * Atomically subtracts @i from @v and returns
  74  * true if the result is zero, or false for all
  75  * other cases.
  76  */
  77 static __inline__ int atomic_sub_and_test(int i, atomic_t *v)
  78 {
  79         unsigned char c;
  80
  81         __asm__ __volatile__(
  82                 LOCK_PREFIX "subl %2,%0; sete %1"
  83                 :"+m" (v->counter), "=qm" (c)
  84                 :"ir" (i) : "memory");
  85         return c;
  86 }
  87
  88 /**
  89  * atomic_inc - increment atomic variable
  90  * @v: pointer of type atomic_t
  91  *
  92  * Atomically increments @v by 1.
  93  */
  94 static __inline__ void atomic_inc(atomic_t *v)
  95 {
  96         __asm__ __volatile__(
  97                 LOCK_PREFIX "incl %0"
  98                 :"+m" (v->counter));
  99 }
 100
 101 /**
 102  * atomic_dec - decrement atomic variable
 103  * @v: pointer of type atomic_t
 104  *
 105  * Atomically decrements @v by 1.
 106  */
 107 static __inline__ void atomic_dec(atomic_t *v)
 108 {
 109         __asm__ __volatile__(
 110                 LOCK_PREFIX "decl %0"
 111                 :"+m" (v->counter));
 112 }
 113
 114 /**
 115  * atomic_dec_and_test - decrement and test
 116  * @v: pointer of type atomic_t
 117  *
 118  * Atomically decrements @v by 1 and
 119  * returns true if the result is 0, or false for all other
 120  * cases.
 121  */
 122 static __inline__ int atomic_dec_and_test(atomic_t *v)
 123 {
 124         unsigned char c;
 125
 126         __asm__ __volatile__(
 127                 LOCK_PREFIX "decl %0; sete %1"
 128                 :"+m" (v->counter), "=qm" (c)
 129                 : : "memory");
 130         return c != 0;
 131 }
 132
 133 /**
 134  * atomic_inc_and_test - increment and test
 135  * @v: pointer of type atomic_t
 136  *
 137  * Atomically increments @v by 1
 138  * and returns true if the result is zero, or false for all
 139  * other cases.
 140  */
 141 static __inline__ int atomic_inc_and_test(atomic_t *v)
 142 {
 143         unsigned char c;
 144
 145         __asm__ __volatile__(
 146                 LOCK_PREFIX "incl %0; sete %1"
 147                 :"+m" (v->counter), "=qm" (c)
 148                 : : "memory");
 149         return c != 0;
 150 }
 151
 152 /**
 153  * atomic_add_negative - add and test if negative
 154  * @v: pointer of type atomic_t
 155  * @i: integer value to add
 156  *
 157  * Atomically adds @i to @v and returns true
 158  * if the result is negative, or false when
 159  * result is greater than or equal to zero.
 160  */
 161 static __inline__ int atomic_add_negative(int i, atomic_t *v)
 162 {
 163         unsigned char c;
 164
 165         __asm__ __volatile__(
 166                 LOCK_PREFIX "addl %2,%0; sets %1"
 167                 :"+m" (v->counter), "=qm" (c)
 168                 :"ir" (i) : "memory");
 169         return c;
 170 }
 171
 172 /**
 173  * atomic_add_return - add and return
 174  * @v: pointer of type atomic_t
 175  * @i: integer value to add
 176  *
 177  * Atomically adds @i to @v and returns @i + @v
 178  */
 179 static __inline__ int atomic_add_return(int i, atomic_t *v)
 180 {
 181         int __i;
 182 #ifdef CONFIG_M386
 183         unsigned long flags;
 184         if(unlikely(boot_cpu_data.x86==3))
 185                 goto no_xadd;
 186 #endif
 187         /* Modern 486+ processor */
 188         __i = i;
 189         __asm__ __volatile__(
 190                 LOCK_PREFIX "xaddl %0, %1"
 191                 :"+r" (i), "+m" (v->counter)
 192                 : : "memory");
 193         return i + __i;
 194
 195 #ifdef CONFIG_M386
 196 no_xadd: /* Legacy 386 processor */
 197         local_irq_save(flags);
 198         __i = atomic_read(v);
 199         atomic_set(v, i + __i);
 200         local_irq_restore(flags);
 201         return i + __i;
 202 #endif
 203 }
 204
 205 static __inline__ int atomic_sub_return(int i, atomic_t *v)
 206 {
 207         return atomic_add_return(-i,v);
 208 }
 209
 210 #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
 211 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
 212
 213 /**
 214  * atomic_add_unless - add unless the number is already a given value
 215  * @v: pointer of type atomic_t
 216  * @a: the amount to add to v...
 217  * @u: ...unless v is equal to u.
 218  *
 219  * Atomically adds @a to @v, so long as @v was not already @u.
 220  * Returns non-zero if @v was not @u, and zero otherwise.
 221  */
 222 #define atomic_add_unless(v, a, u)                              \
 223 ({                                                              \
 224         int c, old;                                             \
 225         c = atomic_read(v);                                     \
 226         for (;;) {                                              \
 227                 if (unlikely(c == (u)))                         \
 228                         break;                                  \
 229                 old = atomic_cmpxchg((v), c, c + (a));          \
 230                 if (likely(old == c))                           \
 231                         break;                                  \
 232                 c = old;                                        \
 233         }                                                       \
 234         c != (u);                                               \
 235 })
 236 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
 237
 238 #define atomic_inc_return(v)  (atomic_add_return(1,v))
 239 #define atomic_dec_return(v)  (atomic_sub_return(1,v))
 240
 241 /* These are x86-specific, used by some header files */
 242 #define atomic_clear_mask(mask, addr) \
 243 __asm__ __volatile__(LOCK_PREFIX "andl %0,%1" \
 244 : : "r" (~(mask)),"m" (*addr) : "memory")
 245
 246 #define atomic_set_mask(mask, addr) \
 247 __asm__ __volatile__(LOCK_PREFIX "orl %0,%1" \
 248 : : "r" (mask),"m" (*(addr)) : "memory")
 249
 250 /* Atomic operations are already serializing on x86 */
 251 #define smp_mb__before_atomic_dec()     barrier()
 252 #define smp_mb__after_atomic_dec()      barrier()
 253 #define smp_mb__before_atomic_inc()     barrier()
 254 #define smp_mb__after_atomic_inc()      barrier()
 255
 256 #include <asm-generic/atomic.h>
 257 #endif