diff options
| -rw-r--r-- | src/internal/fork_impl.h | 1 | ||||
| -rw-r--r-- | src/ldso/dlerror.c | 34 | ||||
| -rw-r--r-- | src/process/fork.c | 2 |
3 files changed, 18 insertions, 19 deletions
diff --git a/src/internal/fork_impl.h b/src/internal/fork_impl.h index 5892c13b..ae3a79e5 100644 --- a/src/internal/fork_impl.h +++ b/src/internal/fork_impl.h @@ -2,7 +2,6 @@ extern hidden volatile int *const __at_quick_exit_lockptr; extern hidden volatile int *const __atexit_lockptr; -extern hidden volatile int *const __dlerror_lockptr; extern hidden volatile int *const __gettext_lockptr; extern hidden volatile int *const __locale_lockptr; extern hidden volatile int *const __random_lockptr; diff --git a/src/ldso/dlerror.c b/src/ldso/dlerror.c index afe59253..dae0f3a9 100644 --- a/src/ldso/dlerror.c +++ b/src/ldso/dlerror.c @@ -3,8 +3,7 @@ #include <stdarg.h> #include "pthread_impl.h" #include "dynlink.h" -#include "lock.h" -#include "fork_impl.h" +#include "atomic.h" #define malloc __libc_malloc #define calloc __libc_calloc @@ -23,28 +22,31 @@ char *dlerror() return s; } -static volatile int freebuf_queue_lock[1]; -static void **freebuf_queue; -volatile int *const __dlerror_lockptr = freebuf_queue_lock; +/* Atomic singly-linked list, used to store list of thread-local dlerror + * buffers for deferred free. They cannot be freed at thread exit time + * because, by the time it's known they can be freed, the exiting thread + * is in a highly restrictive context where it cannot call (even the + * libc-internal) free. It also can't take locks; thus the atomic list. */ + +static void *volatile freebuf_queue; void __dl_thread_cleanup(void) { pthread_t self = __pthread_self(); - if (self->dlerror_buf && self->dlerror_buf != (void *)-1) { - LOCK(freebuf_queue_lock); - void **p = (void **)self->dlerror_buf; - *p = freebuf_queue; - freebuf_queue = p; - UNLOCK(freebuf_queue_lock); - } + if (!self->dlerror_buf || self->dlerror_buf == (void *)-1) + return; + void *h; + do { + h = freebuf_queue; + *(void **)self->dlerror_buf = h; + } while (a_cas_p(&freebuf_queue, h, self->dlerror_buf) != h); } hidden void __dl_vseterr(const char *fmt, va_list ap) { - LOCK(freebuf_queue_lock); - void **q = freebuf_queue; - freebuf_queue = 0; - UNLOCK(freebuf_queue_lock); + void **q; + do q = freebuf_queue; + while (q && a_cas_p(&freebuf_queue, q, 0) != q); while (q) { void **p = *q; diff --git a/src/process/fork.c b/src/process/fork.c index 54bc2892..ff71845c 100644 --- a/src/process/fork.c +++ b/src/process/fork.c @@ -9,7 +9,6 @@ static volatile int *const dummy_lockptr = 0; weak_alias(dummy_lockptr, __at_quick_exit_lockptr); weak_alias(dummy_lockptr, __atexit_lockptr); -weak_alias(dummy_lockptr, __dlerror_lockptr); weak_alias(dummy_lockptr, __gettext_lockptr); weak_alias(dummy_lockptr, __locale_lockptr); weak_alias(dummy_lockptr, __random_lockptr); @@ -24,7 +23,6 @@ weak_alias(dummy_lockptr, __vmlock_lockptr); static volatile int *const *const atfork_locks[] = { &__at_quick_exit_lockptr, &__atexit_lockptr, - &__dlerror_lockptr, &__gettext_lockptr, &__locale_lockptr, &__random_lockptr, |