diff options
| author | Will Deacon <will@kernel.org> | 2019-11-21 11:58:53 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-11-25 09:14:13 +0100 |
| commit | 23e6b169c9917fbd77534f8c5f378cb073f548bd (patch) | |
| tree | 2e5029ea095271946a7f5cd7f7de4d47db82bbba /include/linux/refcount.h | |
| parent | 3ef240eaff36b8119ac9e2ea17cbf41179c930ba (diff) | |
locking/refcount: Define constants for saturation and max refcount values
The REFCOUNT_FULL implementation uses a different saturation point than
the x86 implementation, which means that the shared refcount code in
lib/refcount.c (e.g. refcount_dec_not_one()) needs to be aware of the
difference.
Rather than duplicate the definitions from the lkdtm driver, instead
move them into <linux/refcount.h> and update all references accordingly.
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/20191121115902.2551-2-will@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/refcount.h')
| -rw-r--r-- | include/linux/refcount.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/include/linux/refcount.h b/include/linux/refcount.h index e28cce21bad6..79f62e8d2256 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -4,6 +4,7 @@ #include <linux/atomic.h> #include <linux/compiler.h> +#include <linux/limits.h> #include <linux/spinlock_types.h> struct mutex; @@ -12,7 +13,7 @@ struct mutex; * struct refcount_t - variant of atomic_t specialized for reference counts * @refs: atomic_t counter field * - * The counter saturates at UINT_MAX and will not move once + * The counter saturates at REFCOUNT_SATURATED and will not move once * there. This avoids wrapping the counter and causing 'spurious' * use-after-free bugs. */ @@ -56,6 +57,9 @@ 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 @@ -68,6 +72,10 @@ extern void refcount_dec_checked(refcount_t *r); #define refcount_dec refcount_dec_checked #else + +#define REFCOUNT_MAX INT_MAX +#define REFCOUNT_SATURATED (INT_MIN / 2) + # ifdef CONFIG_ARCH_HAS_REFCOUNT # include <asm/refcount.h> # else |