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-rw-r--r--src/internal/fork_impl.h1
-rw-r--r--src/ldso/dlerror.c34
-rw-r--r--src/process/fork.c2
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,