From: Will Deacon will@kernel.org
[ Upstream commit 7221762c48c6bbbcc6cc51d8b803c06930215e34 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/refcount.h | 25 ++++++------------- lib/refcount.c | 54 +++++++++++++++++++++------------------- 2 files changed, 36 insertions(+), 43 deletions(-)
diff --git a/include/linux/refcount.h b/include/linux/refcount.h index 89066a1471dd..edd505d1a23b 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -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
diff --git a/lib/refcount.c b/lib/refcount.c index 719b0bc42ab1..a2f670998cee 100644 --- a/lib/refcount.c +++ b/lib/refcount.c @@ -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