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locking/refcount: Consolidate implementations of refcount_t

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The generic implementation of refcount_t should be good enough for
everybody, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely,
leaving the generic implementation enabled unconditionally.

Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-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/20191121115902.2551-9-will@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Will Deacon
2019-11-21 11:59:00 +00:00
committed by Ingo Molnar
parent 65b0085524
commit fb041bb7c0
11 changed files with 59 additions and 308 deletions
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158
include/linux/refcount.h
View File

@@ -1,64 +1,4 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_REFCOUNT_H
#define _LINUX_REFCOUNT_H
#include <linux/atomic.h>
#include <linux/compiler.h>
#include <linux/limits.h>
#include <linux/spinlock_types.h>
struct mutex;
/**
* struct refcount_t - variant of atomic_t specialized for reference counts
* @refs: atomic_t counter field
*
* The counter saturates at REFCOUNT_SATURATED and will not move once
* there. This avoids wrapping the counter and causing 'spurious'
* use-after-free bugs.
*/
typedef struct refcount_struct {
atomic_t refs;
} refcount_t;
#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
#define REFCOUNT_MAX INT_MAX
#define REFCOUNT_SATURATED (INT_MIN / 2)
enum refcount_saturation_type {
REFCOUNT_ADD_NOT_ZERO_OVF,
REFCOUNT_ADD_OVF,
REFCOUNT_ADD_UAF,
REFCOUNT_SUB_UAF,
REFCOUNT_DEC_LEAK,
};
void refcount_warn_saturate(refcount_t *r, enum refcount_saturation_type t);
/**
* refcount_set - set a refcount's value
* @r: the refcount
* @n: value to which the refcount will be set
*/
static inline void refcount_set(refcount_t *r, int n)
{
atomic_set(&r->refs, n);
}
/**
* refcount_read - get a refcount's value
* @r: the refcount
*
* Return: the refcount's value
*/
static inline unsigned int refcount_read(const refcount_t *r)
{
return atomic_read(&r->refs);
}
#ifdef CONFIG_REFCOUNT_FULL
#include <linux/bug.h>
/*
* Variant of atomic_t specialized for reference counts.
*
@@ -136,6 +76,64 @@ static inline unsigned int refcount_read(const refcount_t *r)
*
*/
#ifndef _LINUX_REFCOUNT_H
#define _LINUX_REFCOUNT_H
#include <linux/atomic.h>
#include <linux/bug.h>
#include <linux/compiler.h>
#include <linux/limits.h>
#include <linux/spinlock_types.h>
struct mutex;
/**
* struct refcount_t - variant of atomic_t specialized for reference counts
* @refs: atomic_t counter field
*
* The counter saturates at REFCOUNT_SATURATED and will not move once
* there. This avoids wrapping the counter and causing 'spurious'
* use-after-free bugs.
*/
typedef struct refcount_struct {
atomic_t refs;
} refcount_t;
#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
#define REFCOUNT_MAX INT_MAX
#define REFCOUNT_SATURATED (INT_MIN / 2)
enum refcount_saturation_type {
REFCOUNT_ADD_NOT_ZERO_OVF,
REFCOUNT_ADD_OVF,
REFCOUNT_ADD_UAF,
REFCOUNT_SUB_UAF,
REFCOUNT_DEC_LEAK,
};
void refcount_warn_saturate(refcount_t *r, enum refcount_saturation_type t);
/**
* refcount_set - set a refcount's value
* @r: the refcount
* @n: value to which the refcount will be set
*/
static inline void refcount_set(refcount_t *r, int n)
{
atomic_set(&r->refs, n);
}
/**
* refcount_read - get a refcount's value
* @r: the refcount
*
* Return: the refcount's value
*/
static inline unsigned int refcount_read(const refcount_t *r)
{
return atomic_read(&r->refs);
}
/**
* refcount_add_not_zero - add a value to a refcount unless it is 0
* @i: the value to add to the refcount
@@ -298,46 +296,6 @@ static inline void refcount_dec(refcount_t *r)
if (unlikely(atomic_fetch_sub_release(1, &r->refs) <= 1))
refcount_warn_saturate(r, REFCOUNT_DEC_LEAK);
}
#else /* CONFIG_REFCOUNT_FULL */
# ifdef CONFIG_ARCH_HAS_REFCOUNT
# include <asm/refcount.h>
# else
static inline __must_check bool refcount_add_not_zero(int i, refcount_t *r)
{
return atomic_add_unless(&r->refs, i, 0);
}
static inline void refcount_add(int i, refcount_t *r)
{
atomic_add(i, &r->refs);
}
static inline __must_check bool refcount_inc_not_zero(refcount_t *r)
{
return atomic_add_unless(&r->refs, 1, 0);
}
static inline void refcount_inc(refcount_t *r)
{
atomic_inc(&r->refs);
}
static inline __must_check bool refcount_sub_and_test(int i, refcount_t *r)
{
return atomic_sub_and_test(i, &r->refs);
}
static inline __must_check bool refcount_dec_and_test(refcount_t *r)
{
return atomic_dec_and_test(&r->refs);
}
static inline void refcount_dec(refcount_t *r)
{
atomic_dec(&r->refs);
}
# endif /* !CONFIG_ARCH_HAS_REFCOUNT */
#endif /* !CONFIG_REFCOUNT_FULL */
extern __must_check bool refcount_dec_if_one(refcount_t *r);
extern __must_check bool refcount_dec_not_one(refcount_t *r);