upstream/bind9
1
0
Fork 0
mirror of https://github.com/isc-projects/bind9.git synced 2026-05-28 04:34:54 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

Use release memory ordering when incrementing reference counter

Browse source 
As the relaxed memory ordering doesn't ensure any memory
synchronization, it is possible that the increment will succeed even
in the case when it should not - there is a race between
atomic_fetch_sub(..., acq_rel) and atomic_fetch_add(..., relaxed).
Only the result is consistent, but the previous value for both calls
could be same when both calls are executed at the same time.

(cherry picked from commit 88227ea665)
This commit is contained in:
Ondřej Surý 2024-09-09 16:03:53 +02:00 committed by Ondřej Surý
parent aa078bdd37
commit 5701bf9dab
No known key found for this signature in database
GPG key ID: 2820F37E873DEA41
1 changed files with 2 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
lib/isc/include/isc/refcount.h
View file

@ -70,7 +70,7 @@ typedef atomic_uint_fast32_t isc_refcount_t;
#define isc_refcount_increment0(target) \
({ \
uint_fast32_t __v; \
__v = atomic_fetch_add_relaxed(target, 1); \
__v = atomic_fetch_add_release(target, 1); \
INSIST(__v < UINT32_MAX); \
__v; \
})
@ -83,7 +83,7 @@ typedef atomic_uint_fast32_t isc_refcount_t;
#define isc_refcount_increment(target) \
({ \
uint_fast32_t __v; \
__v = atomic_fetch_add_relaxed(target, 1); \
__v = atomic_fetch_add_release(target, 1); \
INSIST(__v > 0 && __v < UINT32_MAX); \
__v; \
})