--- /dev/null
+#ifndef __ASM_SPINLOCK_H
+#define __ASM_SPINLOCK_H
+
+#include <asm/atomic.h>
+#include <asm/rwlock.h>
+#include <asm/page.h>
+#include <linux/config.h>
+#include <linux/compiler.h>
+
+/*
+ * Your basic SMP spinlocks, allowing only a single CPU anywhere
+ *
+ * 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.
+ *
+ * (the type definitions are in asm/spinlock_types.h)
+ */
+
+#define __raw_spin_is_locked(x) \
+ (*(volatile signed char *)(&(x)->slock) <= 0)
+
+#define __raw_spin_lock_string \
+ "\n1:\t" \
+ "lock ; decb %0\n\t" \
+ "jns 3f\n" \
+ "2:\t" \
+ "rep;nop\n\t" \
+ "cmpb $0,%0\n\t" \
+ "jle 2b\n\t" \
+ "jmp 1b\n" \
+ "3:\n\t"
+
+#define __raw_spin_lock_string_flags \
+ "\n1:\t" \
+ "lock ; decb %0\n\t" \
+ "jns 5f\n" \
+ "2:\t" \
+ "testl $0x200, %1\n\t" \
+ "jz 4f\n\t" \
+ "#sti\n" \
+ "3:\t" \
+ "rep;nop\n\t" \
+ "cmpb $0, %0\n\t" \
+ "jle 3b\n\t" \
+ "#cli\n\t" \
+ "jmp 1b\n" \
+ "4:\t" \
+ "rep;nop\n\t" \
+ "cmpb $0, %0\n\t" \
+ "jg 1b\n\t" \
+ "jmp 4b\n" \
+ "5:\n\t"
+
+#define __raw_spin_lock_string_up \
+ "\n\tdecb %0"
+
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
+{
+ alternative_smp(
+ __raw_spin_lock_string,
+ __raw_spin_lock_string_up,
+ "=m" (lock->slock) : : "memory");
+}
+
+static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
+{
+ alternative_smp(
+ __raw_spin_lock_string_flags,
+ __raw_spin_lock_string_up,
+ "=m" (lock->slock) : "r" (flags) : "memory");
+}
+
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
+{
+ char oldval;
+ __asm__ __volatile__(
+ "xchgb %b0,%1"
+ :"=q" (oldval), "=m" (lock->slock)
+ :"0" (0) : "memory");
+ return oldval > 0;
+}
+
+/*
+ * __raw_spin_unlock based on writing $1 to the low byte.
+ * This method works. Despite all the confusion.
+ * (except on PPro SMP or if we are using OOSTORE, so we use xchgb there)
+ * (PPro errata 66, 92)
+ */
+
+#if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE)
+
+#define __raw_spin_unlock_string \
+ "movb $1,%0" \
+ :"=m" (lock->slock) : : "memory"
+
+
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
+{
+ __asm__ __volatile__(
+ __raw_spin_unlock_string
+ );
+}
+
+#else
+
+#define __raw_spin_unlock_string \
+ "xchgb %b0, %1" \
+ :"=q" (oldval), "=m" (lock->slock) \
+ :"0" (oldval) : "memory"
+
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
+{
+ char oldval = 1;
+
+ __asm__ __volatile__(
+ __raw_spin_unlock_string
+ );
+}
+
+#endif
+
+#define __raw_spin_unlock_wait(lock) \
+ do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
+
+/*
+ * 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.
+ *
+ * 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 helpers are in arch/i386/kernel/semaphore.c
+ */
+
+/**
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+#define __raw_read_can_lock(x) ((int)(x)->lock > 0)
+
+/**
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+#define __raw_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS)
+
+static inline void __raw_read_lock(raw_rwlock_t *rw)
+{
+ __build_read_lock(rw, "__read_lock_failed");
+}
+
+static inline void __raw_write_lock(raw_rwlock_t *rw)
+{
+ __build_write_lock(rw, "__write_lock_failed");
+}
+
+static inline int __raw_read_trylock(raw_rwlock_t *lock)
+{
+ atomic_t *count = (atomic_t *)lock;
+ atomic_dec(count);
+ if (atomic_read(count) >= 0)
+ return 1;
+ atomic_inc(count);
+ return 0;
+}
+
+static inline int __raw_write_trylock(raw_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;
+}
+
+static inline void __raw_read_unlock(raw_rwlock_t *rw)
+{
+ asm volatile(LOCK_PREFIX "incl %0" :"=m" (rw->lock) : : "memory");
+}
+
+static inline void __raw_write_unlock(raw_rwlock_t *rw)
+{
+ asm volatile(LOCK_PREFIX "addl $" RW_LOCK_BIAS_STR ", %0"
+ : "=m" (rw->lock) : : "memory");
+}
+
+#endif /* __ASM_SPINLOCK_H */
git://git.onelab.eu / linux-2.6.git / blobdiff