Commit 7221762c authored by Will Deacon's avatar Will Deacon Committed by Ingo Molnar
Browse files

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: default avatarWill Deacon <will@kernel.org>
Reviewed-by: default avatarArd Biesheuvel <ardb@kernel.org>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Tested-by: default avatarHanjun 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: default avatarIngo Molnar <mingo@kernel.org>
parent 97a1420a

include/linux/refcount.h

+7 −18
Original line number Diff line number Diff line
@@ -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

lib/refcount.c

+29 −25
Original line number Diff line number Diff line
@@ -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

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