diff options
Diffstat (limited to 'malloc/thread-m.h')
| -rw-r--r-- | malloc/thread-m.h | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/malloc/thread-m.h b/malloc/thread-m.h index 1598db8ee7..d5b1e2f4b0 100644 --- a/malloc/thread-m.h +++ b/malloc/thread-m.h @@ -207,18 +207,24 @@ int tsd_key_next; typedef int thread_id; +/* The mutex functions used to do absolutely nothing, i.e. lock, + trylock and unlock would always just return 0. However, even + without any concurrently active threads, a mutex can be used + legitimately as an `in use' flag. To make the code that is + protected by a mutex async-signal safe, these macros would have to + be based on atomic test-and-set operations, for example. */ typedef int mutex_t; #define MUTEX_INITIALIZER 0 #define mutex_init(m) (*(m) = 0) -#define mutex_lock(m) (0) -#define mutex_trylock(m) (0) -#define mutex_unlock(m) (0) +#define mutex_lock(m) ((*(m) = 1), 0) +#define mutex_trylock(m) (*(m) ? 1 : ((*(m) = 1), 0)) +#define mutex_unlock(m) (*(m) = 0) typedef void *tsd_key_t; #define tsd_key_create(key, destr) do {} while(0) -#define tsd_setspecific(key, data) do {} while(0) -#define tsd_getspecific(key, vptr) (vptr = NULL) +#define tsd_setspecific(key, data) ((key) = (data)) +#define tsd_getspecific(key, vptr) (vptr = (key)) #define thread_atfork(prepare, parent, child) do {} while(0) |