cregit-Linux how code gets into the kernel

Release 4.12 include/asm-generic/atomic.h

/*
 * Generic C implementation of atomic counter operations. Usable on
 * UP systems only. Do not include in machine independent code.
 *
 * Originally implemented for MN10300.
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#ifndef __ASM_GENERIC_ATOMIC_H

#define __ASM_GENERIC_ATOMIC_H

#include <asm/cmpxchg.h>
#include <asm/barrier.h>

/*
 * atomic_$op() - $op integer to atomic variable
 * @i: integer value to $op
 * @v: pointer to the atomic variable
 *
 * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use
 * smp_mb__{before,after}_atomic().
 */

/*
 * atomic_$op_return() - $op interer to atomic variable and returns the result
 * @i: integer value to $op
 * @v: pointer to the atomic variable
 *
 * Atomically $ops @i to @v. Does imply a full memory barrier.
 */

#ifdef CONFIG_SMP

/* we can build all atomic primitives from cmpxchg */


#define ATOMIC_OP(op, c_op)						\
static inline void atomic_##op(int i, atomic_t *v)                      \
{                                                                       \
        int c, old;                                                     \
                                                                        \
        c = v->counter;                                                 \
        while ((old = cmpxchg(&v->counter, c, c c_op i)) != c)          \
                c = old;                                                \
}


#define ATOMIC_OP_RETURN(op, c_op)					\
static inline int atomic_##op##_return(int i, atomic_t *v)              \
{                                                                       \
        int c, old;                                                     \
                                                                        \
        c = v->counter;                                                 \
        while ((old = cmpxchg(&v->counter, c, c c_op i)) != c)          \
                c = old;                                                \
                                                                        \
        return c c_op i;                                                \
}


#define ATOMIC_FETCH_OP(op, c_op)					\
static inline int atomic_fetch_##op(int i, atomic_t *v)                 \
{                                                                       \
        int c, old;                                                     \
                                                                        \
        c = v->counter;                                                 \
        while ((old = cmpxchg(&v->counter, c, c c_op i)) != c)          \
                c = old;                                                \
                                                                        \
        return c;                                                       \
}

#else

#include <linux/irqflags.h>


#define ATOMIC_OP(op, c_op)						\
static inline void atomic_##op(int i, atomic_t *v)                      \
{                                                                       \
        unsigned long flags;                                            \
                                                                        \
        raw_local_irq_save(flags);                                      \
        v->counter = v->counter c_op i;                                 \
        raw_local_irq_restore(flags);                                   \
}


#define ATOMIC_OP_RETURN(op, c_op)					\
static inline int atomic_##op##_return(int i, atomic_t *v)              \
{                                                                       \
        unsigned long flags;                                            \
        int ret;                                                        \
                                                                        \
        raw_local_irq_save(flags);                                      \
        ret = (v->counter = v->counter c_op i);                         \
        raw_local_irq_restore(flags);                                   \
                                                                        \
        return ret;                                                     \
}


#define ATOMIC_FETCH_OP(op, c_op)					\
static inline int atomic_fetch_##op(int i, atomic_t *v)                 \
{                                                                       \
        unsigned long flags;                                            \
        int ret;                                                        \
                                                                        \
        raw_local_irq_save(flags);                                      \
        ret = v->counter;                                               \
        v->counter = v->counter c_op i;                                 \
        raw_local_irq_restore(flags);                                   \
                                                                        \
        return ret;                                                     \
}

#endif /* CONFIG_SMP */

#ifndef atomic_add_return
ATOMIC_OP_RETURN(add, +)
#endif

#ifndef atomic_sub_return
ATOMIC_OP_RETURN(sub, -)
#endif

#ifndef atomic_fetch_add
ATOMIC_FETCH_OP(add, +)
#endif

#ifndef atomic_fetch_sub
ATOMIC_FETCH_OP(sub, -)
#endif

#ifndef atomic_fetch_and
ATOMIC_FETCH_OP(and, &)
#endif

#ifndef atomic_fetch_or
ATOMIC_FETCH_OP(or, |)
#endif

#ifndef atomic_fetch_xor
ATOMIC_FETCH_OP(xor, ^)
#endif

#ifndef atomic_and
ATOMIC_OP(and, &)
#endif

#ifndef atomic_or
ATOMIC_OP(or, |)
#endif

#ifndef atomic_xor
ATOMIC_OP(xor, ^)
#endif


#undef ATOMIC_FETCH_OP

#undef ATOMIC_OP_RETURN

#undef ATOMIC_OP

/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 */


#define ATOMIC_INIT(i)	{ (i) }

/**
 * atomic_read - read atomic variable
 * @v: pointer of type atomic_t
 *
 * Atomically reads the value of @v.
 */
#ifndef atomic_read

#define atomic_read(v)	READ_ONCE((v)->counter)
#endif

/**
 * atomic_set - set atomic variable
 * @v: pointer of type atomic_t
 * @i: required value
 *
 * Atomically sets the value of @v to @i.
 */

#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))

#include <linux/irqflags.h>


static inline int atomic_add_negative(int i, atomic_t *v) { return atomic_add_return(i, v) < 0; }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann24100.00%1100.00%
Total24100.00%1100.00%


static inline void atomic_add(int i, atomic_t *v) { atomic_add_return(i, v); }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann21100.00%1100.00%
Total21100.00%1100.00%


static inline void atomic_sub(int i, atomic_t *v) { atomic_sub_return(i, v); }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann21100.00%1100.00%
Total21100.00%1100.00%


static inline void atomic_inc(atomic_t *v) { atomic_add_return(1, v); }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann18100.00%1100.00%
Total18100.00%1100.00%


static inline void atomic_dec(atomic_t *v) { atomic_sub_return(1, v); }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann18100.00%1100.00%
Total18100.00%1100.00%

#define atomic_dec_return(v) atomic_sub_return(1, (v)) #define atomic_inc_return(v) atomic_add_return(1, (v)) #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) #define atomic_dec_and_test(v) (atomic_dec_return(v) == 0) #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0) #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) #ifndef __atomic_add_unless
static inline int __atomic_add_unless(atomic_t *v, int a, int u) { int c, old; c = atomic_read(v); while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) c = old; return c; }

Contributors

PersonTokensPropCommitsCommitProp
Mathieu Lacage5186.44%133.33%
Arnd Bergmann711.86%133.33%
Arun Sharma11.69%133.33%
Total59100.00%3100.00%

#endif #endif /* __ASM_GENERIC_ATOMIC_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra18639.91%637.50%
Arnd Bergmann18239.06%16.25%
Mathieu Lacage6914.81%16.25%
Mike Frysinger163.43%212.50%
Stefan Kristiansson51.07%16.25%
David Howells40.86%212.50%
Arun Sharma20.43%212.50%
Peter Fritzsche20.43%16.25%
Total466100.00%16100.00%
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