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locking/refcount: Remove unused refcount_*_checked() variants 

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>
This commit is contained in:
Will Deacon 2019-11-21 11:58:55 +00:00 committed by Ingo Molnar
parent 97a1420adf
commit 7221762c48
2 changed files with 36 additions and 43 deletions
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25
include/linux/refcount.h
View File

@ -44,32 +44,21 @@ static inline unsigned int refcount_read(const refcount_t *r)
return atomic_read(&r->refs);
}
extern __must_check bool refcount_add_not_zero_checked(int i, refcount_t *r);
extern void refcount_add_checked(int i, refcount_t *r);
extern __must_check bool refcount_inc_not_zero_checked(refcount_t *r);
extern void refcount_inc_checked(refcount_t *r);
extern __must_check bool refcount_sub_and_test_checked(int i, refcount_t *r);
extern __must_check bool refcount_dec_and_test_checked(refcount_t *r);
extern void refcount_dec_checked(refcount_t *r);
#ifdef CONFIG_REFCOUNT_FULL
#define REFCOUNT_MAX (UINT_MAX - 1)
#define REFCOUNT_SATURATED UINT_MAX
#define refcount_add_not_zero refcount_add_not_zero_checked
#define refcount_add refcount_add_checked
extern __must_check bool refcount_add_not_zero(int i, refcount_t *r);
extern void refcount_add(int i, refcount_t *r);
#define refcount_inc_not_zero refcount_inc_not_zero_checked
#define refcount_inc refcount_inc_checked
extern __must_check bool refcount_inc_not_zero(refcount_t *r);
extern void refcount_inc(refcount_t *r);
#define refcount_sub_and_test refcount_sub_and_test_checked
extern __must_check bool refcount_sub_and_test(int i, refcount_t *r);
#define refcount_dec_and_test refcount_dec_and_test_checked
#define refcount_dec refcount_dec_checked
extern __must_check bool refcount_dec_and_test(refcount_t *r);
extern void refcount_dec(refcount_t *r);
#else

54
lib/refcount.c
View File

@ -43,8 +43,10 @@
#include <linux/spinlock.h>
#include <linux/bug.h>
#ifdef CONFIG_REFCOUNT_FULL
/**
* refcount_add_not_zero_checked - add a value to a refcount unless it is 0
* refcount_add_not_zero - add a value to a refcount unless it is 0
* @i: the value to add to the refcount
* @r: the refcount
*
@ -61,7 +63,7 @@
*
* Return: false if the passed refcount is 0, true otherwise
*/
bool refcount_add_not_zero_checked(int i, refcount_t *r)
bool refcount_add_not_zero(int i, refcount_t *r)
{
unsigned int new, val = atomic_read(&r->refs);
@ -83,10 +85,10 @@ bool refcount_add_not_zero_checked(int i, refcount_t *r)
return true;
}
EXPORT_SYMBOL(refcount_add_not_zero_checked);
EXPORT_SYMBOL(refcount_add_not_zero);
/**
* refcount_add_checked - add a value to a refcount
* refcount_add - add a value to a refcount
* @i: the value to add to the refcount
* @r: the refcount
*
@ -101,14 +103,14 @@ EXPORT_SYMBOL(refcount_add_not_zero_checked);
* cases, refcount_inc(), or one of its variants, should instead be used to
* increment a reference count.
*/
void refcount_add_checked(int i, refcount_t *r)
void refcount_add(int i, refcount_t *r)
{
WARN_ONCE(!refcount_add_not_zero_checked(i, r), "refcount_t: addition on 0; use-after-free.\n");
WARN_ONCE(!refcount_add_not_zero(i, r), "refcount_t: addition on 0; use-after-free.\n");
}
EXPORT_SYMBOL(refcount_add_checked);
EXPORT_SYMBOL(refcount_add);
/**
* refcount_inc_not_zero_checked - increment a refcount unless it is 0
* refcount_inc_not_zero - increment a refcount unless it is 0
* @r: the refcount to increment
*
* Similar to atomic_inc_not_zero(), but will saturate at REFCOUNT_SATURATED
@ -120,7 +122,7 @@ EXPORT_SYMBOL(refcount_add_checked);
*
* Return: true if the increment was successful, false otherwise
*/
bool refcount_inc_not_zero_checked(refcount_t *r)
bool refcount_inc_not_zero(refcount_t *r)
{
unsigned int new, val = atomic_read(&r->refs);
@ -140,10 +142,10 @@ bool refcount_inc_not_zero_checked(refcount_t *r)
return true;
}
EXPORT_SYMBOL(refcount_inc_not_zero_checked);
EXPORT_SYMBOL(refcount_inc_not_zero);
/**
* refcount_inc_checked - increment a refcount
* refcount_inc - increment a refcount
* @r: the refcount to increment
*
* Similar to atomic_inc(), but will saturate at REFCOUNT_SATURATED and WARN.
@ -154,14 +156,14 @@ EXPORT_SYMBOL(refcount_inc_not_zero_checked);
* Will WARN if the refcount is 0, as this represents a possible use-after-free
* condition.
*/
void refcount_inc_checked(refcount_t *r)
void refcount_inc(refcount_t *r)
{
WARN_ONCE(!refcount_inc_not_zero_checked(r), "refcount_t: increment on 0; use-after-free.\n");
WARN_ONCE(!refcount_inc_not_zero(r), "refcount_t: increment on 0; use-after-free.\n");
}
EXPORT_SYMBOL(refcount_inc_checked);
EXPORT_SYMBOL(refcount_inc);
/**
* refcount_sub_and_test_checked - subtract from a refcount and test if it is 0
* refcount_sub_and_test - subtract from a refcount and test if it is 0
* @i: amount to subtract from the refcount
* @r: the refcount
*
@ -180,7 +182,7 @@ EXPORT_SYMBOL(refcount_inc_checked);
*
* Return: true if the resulting refcount is 0, false otherwise
*/
bool refcount_sub_and_test_checked(int i, refcount_t *r)
bool refcount_sub_and_test(int i, refcount_t *r)
{
unsigned int new, val = atomic_read(&r->refs);
@ -203,10 +205,10 @@ bool refcount_sub_and_test_checked(int i, refcount_t *r)
return false;
}
EXPORT_SYMBOL(refcount_sub_and_test_checked);
EXPORT_SYMBOL(refcount_sub_and_test);
/**
* refcount_dec_and_test_checked - decrement a refcount and test if it is 0
* refcount_dec_and_test - decrement a refcount and test if it is 0
* @r: the refcount
*
* Similar to atomic_dec_and_test(), it will WARN on underflow and fail to
@ -218,14 +220,14 @@ EXPORT_SYMBOL(refcount_sub_and_test_checked);
*
* Return: true if the resulting refcount is 0, false otherwise
*/
bool refcount_dec_and_test_checked(refcount_t *r)
bool refcount_dec_and_test(refcount_t *r)
{
return refcount_sub_and_test_checked(1, r);
return refcount_sub_and_test(1, r);
}
EXPORT_SYMBOL(refcount_dec_and_test_checked);
EXPORT_SYMBOL(refcount_dec_and_test);
/**
* refcount_dec_checked - decrement a refcount
* refcount_dec - decrement a refcount
* @r: the refcount
*
* Similar to atomic_dec(), it will WARN on underflow and fail to decrement
@ -234,11 +236,13 @@ EXPORT_SYMBOL(refcount_dec_and_test_checked);
* Provides release memory ordering, such that prior loads and stores are done
* before.
*/
void refcount_dec_checked(refcount_t *r)
void refcount_dec(refcount_t *r)
{
WARN_ONCE(refcount_dec_and_test_checked(r), "refcount_t: decrement hit 0; leaking memory.\n");
WARN_ONCE(refcount_dec_and_test(r), "refcount_t: decrement hit 0; leaking memory.\n");
}
EXPORT_SYMBOL(refcount_dec_checked);
EXPORT_SYMBOL(refcount_dec);
#endif /* CONFIG_REFCOUNT_FULL */
/**
* refcount_dec_if_one - decrement a refcount if it is 1