include/asm-x86/atomic_32.h

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