Loading...
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 | #ifndef __ASM_SPINLOCK_H #define __ASM_SPINLOCK_H #include <asm/atomic.h> #include <asm/rwlock.h> #include <asm/page.h> #include <linux/config.h> extern int printk(const char * fmt, ...) __attribute__ ((format (printf, 1, 2))); /* * Your basic SMP spinlocks, allowing only a single CPU anywhere */ typedef struct { volatile unsigned int lock; #ifdef CONFIG_DEBUG_SPINLOCK unsigned magic; #endif } spinlock_t; #define SPINLOCK_MAGIC 0xdead4ead #ifdef CONFIG_DEBUG_SPINLOCK #define SPINLOCK_MAGIC_INIT , SPINLOCK_MAGIC #else #define SPINLOCK_MAGIC_INIT /* */ #endif #define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 SPINLOCK_MAGIC_INIT } #define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0) /* * Simple spin lock operations. There are two variants, one clears IRQ's * on the local processor, one does not. * * We make no fairness assumptions. They have a cost. */ #define spin_is_locked(x) (*(volatile signed char *)(&(x)->lock) <= 0) #define spin_unlock_wait(x) do { barrier(); } while(spin_is_locked(x)) #define spin_lock_string \ "\n1:\t" \ "lock ; decb %0\n\t" \ "js 2f\n" \ LOCK_SECTION_START("") \ "2:\t" \ "rep;nop\n\t" \ "cmpb $0,%0\n\t" \ "jle 2b\n\t" \ "jmp 1b\n" \ LOCK_SECTION_END /* * This works. Despite all the confusion. * (except on PPro SMP or if we are using OOSTORE) * (PPro errata 66, 92) */ #if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE) #define spin_unlock_string \ "movb $1,%0" \ :"=m" (lock->lock) : : "memory" static inline void _raw_spin_unlock(spinlock_t *lock) { #ifdef CONFIG_DEBUG_SPINLOCK if (lock->magic != SPINLOCK_MAGIC) BUG(); if (!spin_is_locked(lock)) BUG(); #endif __asm__ __volatile__( spin_unlock_string ); } #else #define spin_unlock_string \ "xchgb %b0, %1" \ :"=q" (oldval), "=m" (lock->lock) \ :"0" (oldval) : "memory" static inline void _raw_spin_unlock(spinlock_t *lock) { char oldval = 1; #ifdef CONFIG_DEBUG_SPINLOCK if (lock->magic != SPINLOCK_MAGIC) BUG(); if (!spin_is_locked(lock)) BUG(); #endif __asm__ __volatile__( spin_unlock_string ); } #endif static inline int _raw_spin_trylock(spinlock_t *lock) { char oldval; __asm__ __volatile__( "xchgb %b0,%1" :"=q" (oldval), "=m" (lock->lock) :"0" (0) : "memory"); return oldval > 0; } static inline void _raw_spin_lock(spinlock_t *lock) { #ifdef CONFIG_DEBUG_SPINLOCK __label__ here; here: if (lock->magic != SPINLOCK_MAGIC) { printk("eip: %p\n", &&here); BUG(); } #endif __asm__ __volatile__( spin_lock_string :"=m" (lock->lock) : : "memory"); } /* * Read-write spinlocks, allowing multiple readers * but only one writer. * * NOTE! it is quite common to have readers in interrupts * but no interrupt writers. For those circumstances we * can "mix" irq-safe locks - any writer needs to get a * irq-safe write-lock, but readers can get non-irqsafe * read-locks. */ typedef struct { volatile unsigned int lock; #ifdef CONFIG_DEBUG_SPINLOCK unsigned magic; #endif } rwlock_t; #define RWLOCK_MAGIC 0xdeaf1eed #ifdef CONFIG_DEBUG_SPINLOCK #define RWLOCK_MAGIC_INIT , RWLOCK_MAGIC #else #define RWLOCK_MAGIC_INIT /* */ #endif #define RW_LOCK_UNLOCKED (rwlock_t) { RW_LOCK_BIAS RWLOCK_MAGIC_INIT } #define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0) #define rwlock_is_locked(x) ((x)->lock != RW_LOCK_BIAS) /* * On x86, we implement read-write locks as a 32-bit counter * with the high bit (sign) being the "contended" bit. * * The inline assembly is non-obvious. Think about it. * * Changed to use the same technique as rw semaphores. See * semaphore.h for details. -ben */ /* the spinlock helpers are in arch/i386/kernel/semaphore.c */ static inline void _raw_read_lock(rwlock_t *rw) { #ifdef CONFIG_DEBUG_SPINLOCK if (rw->magic != RWLOCK_MAGIC) BUG(); #endif __build_read_lock(rw, "__read_lock_failed"); } static inline void _raw_write_lock(rwlock_t *rw) { #ifdef CONFIG_DEBUG_SPINLOCK if (rw->magic != RWLOCK_MAGIC) BUG(); #endif __build_write_lock(rw, "__write_lock_failed"); } #define _raw_read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory") #define _raw_write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory") static inline int _raw_write_trylock(rwlock_t *lock) { atomic_t *count = (atomic_t *)lock; if (atomic_sub_and_test(RW_LOCK_BIAS, count)) return 1; atomic_add(RW_LOCK_BIAS, count); return 0; } #endif /* __ASM_SPINLOCK_H */ |