diff options
Diffstat (limited to 'src/lib/thread/threads.h')
| -rw-r--r-- | src/lib/thread/threads.h | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/src/lib/thread/threads.h b/src/lib/thread/threads.h index ecf60641b5..4b42b9abd9 100644 --- a/src/lib/thread/threads.h +++ b/src/lib/thread/threads.h @@ -107,7 +107,7 @@ typedef struct atomic_counter_t { atomic_size_t val; } atomic_counter_t; #define ATOMIC_LINKAGE static -#else /* !(defined(HAVE_WORKING_STDATOMIC)) */ +#else /* !defined(HAVE_WORKING_STDATOMIC) */ typedef struct atomic_counter_t { tor_mutex_t mutex; size_t val; @@ -131,7 +131,17 @@ atomic_counter_init(atomic_counter_t *counter) { atomic_init(&counter->val, 0); } -/** Clean up all resources held by an atomic counter. */ +/** Clean up all resources held by an atomic counter. + * + * This usage note applies to the compat_threads implementation of + * atomic_counter_destroy(): + * Destroying a locked mutex is undefined behaviour. Global mutexes may be + * locked when they are passed to this function, because multiple threads can + * still access them. So we can either: + * - destroy on shutdown, and re-initialise when tor re-initialises, or + * - skip destroying and re-initialisation, using a sentinel variable. + * See #31735 for details. + */ static inline void atomic_counter_destroy(atomic_counter_t *counter) { @@ -162,7 +172,7 @@ atomic_counter_exchange(atomic_counter_t *counter, size_t newval) return atomic_exchange(&counter->val, newval); } -#else /* !(defined(HAVE_WORKING_STDATOMIC)) */ +#else /* !defined(HAVE_WORKING_STDATOMIC) */ #endif /* defined(HAVE_WORKING_STDATOMIC) */ #endif /* !defined(TOR_COMPAT_THREADS_H) */ |