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7221762c48
The full-fat refcount implementation is exposed via a set of functions suffixed with "_checked()", the idea being that code can choose to use the more expensive, yet more secure implementation on a case-by-case basis. In reality, this hasn't happened, so with a grand total of zero users, let's remove the checked variants for now by simply dropping the suffix and predicating the out-of-line functions on CONFIG_REFCOUNT_FULL=y. Signed-off-by: Will Deacon <will@kernel.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Hanjun Guo <guohanjun@huawei.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Elena Reshetova <elena.reshetova@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20191121115902.2551-4-will@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
116 lines
2.9 KiB
C
116 lines
2.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_REFCOUNT_H
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#define _LINUX_REFCOUNT_H
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#include <linux/atomic.h>
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#include <linux/compiler.h>
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#include <linux/limits.h>
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#include <linux/spinlock_types.h>
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struct mutex;
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/**
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* struct refcount_t - variant of atomic_t specialized for reference counts
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* @refs: atomic_t counter field
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*
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* The counter saturates at REFCOUNT_SATURATED and will not move once
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* there. This avoids wrapping the counter and causing 'spurious'
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* use-after-free bugs.
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*/
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typedef struct refcount_struct {
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atomic_t refs;
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} refcount_t;
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#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
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/**
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* refcount_set - set a refcount's value
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* @r: the refcount
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* @n: value to which the refcount will be set
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*/
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static inline void refcount_set(refcount_t *r, int n)
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{
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atomic_set(&r->refs, n);
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}
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/**
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* refcount_read - get a refcount's value
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* @r: the refcount
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*
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* Return: the refcount's value
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*/
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static inline unsigned int refcount_read(const refcount_t *r)
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{
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return atomic_read(&r->refs);
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}
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#ifdef CONFIG_REFCOUNT_FULL
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#define REFCOUNT_MAX (UINT_MAX - 1)
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#define REFCOUNT_SATURATED UINT_MAX
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extern __must_check bool refcount_add_not_zero(int i, refcount_t *r);
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extern void refcount_add(int i, refcount_t *r);
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extern __must_check bool refcount_inc_not_zero(refcount_t *r);
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extern void refcount_inc(refcount_t *r);
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extern __must_check bool refcount_sub_and_test(int i, refcount_t *r);
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extern __must_check bool refcount_dec_and_test(refcount_t *r);
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extern void refcount_dec(refcount_t *r);
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#else
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#define REFCOUNT_MAX INT_MAX
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#define REFCOUNT_SATURATED (INT_MIN / 2)
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# ifdef CONFIG_ARCH_HAS_REFCOUNT
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# include <asm/refcount.h>
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# else
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static inline __must_check bool refcount_add_not_zero(int i, refcount_t *r)
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{
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return atomic_add_unless(&r->refs, i, 0);
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}
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static inline void refcount_add(int i, refcount_t *r)
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{
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atomic_add(i, &r->refs);
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}
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static inline __must_check bool refcount_inc_not_zero(refcount_t *r)
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{
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return atomic_add_unless(&r->refs, 1, 0);
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}
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static inline void refcount_inc(refcount_t *r)
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{
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atomic_inc(&r->refs);
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}
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static inline __must_check bool refcount_sub_and_test(int i, refcount_t *r)
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{
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return atomic_sub_and_test(i, &r->refs);
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}
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static inline __must_check bool refcount_dec_and_test(refcount_t *r)
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{
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return atomic_dec_and_test(&r->refs);
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}
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static inline void refcount_dec(refcount_t *r)
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{
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atomic_dec(&r->refs);
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}
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# endif /* !CONFIG_ARCH_HAS_REFCOUNT */
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#endif /* CONFIG_REFCOUNT_FULL */
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extern __must_check bool refcount_dec_if_one(refcount_t *r);
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extern __must_check bool refcount_dec_not_one(refcount_t *r);
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extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock);
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extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock);
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extern __must_check bool refcount_dec_and_lock_irqsave(refcount_t *r,
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spinlock_t *lock,
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unsigned long *flags);
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#endif /* _LINUX_REFCOUNT_H */
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