fix missing synchronization of pthread TSD keys with MT-fork

[musl] / src / thread / pthread_key_create.c

diff --git a/src/thread/pthread_key_create.c b/src/thread/pthread_key_create.c
index c29935c..39770c7 100644 (file)
--- a/src/thread/pthread_key_create.c
+++ b/src/thread/pthread_key_create.c
@@ -1,49 +1,99 @@
 #include "pthread_impl.h"
+#include "fork_impl.h"
 
-const size_t __pthread_tsd_size = sizeof(void *) * PTHREAD_KEYS_MAX;
+volatile size_t __pthread_tsd_size = sizeof(void *) * PTHREAD_KEYS_MAX;
 void *__pthread_tsd_main[PTHREAD_KEYS_MAX] = { 0 };
 
 static void (*keys[PTHREAD_KEYS_MAX])(void *);
 
+static pthread_rwlock_t key_lock = PTHREAD_RWLOCK_INITIALIZER;
+
+static pthread_key_t next_key;
+
 static void nodtor(void *dummy)
 {
 }
 
-int pthread_key_create(pthread_key_t *k, void (*dtor)(void *))
+static void dummy_0(void)
+{
+}
+
+weak_alias(dummy_0, __tl_lock);
+weak_alias(dummy_0, __tl_unlock);
+
+void __pthread_key_atfork(int who)
 {
-       unsigned i = (uintptr_t)&k / 16 % PTHREAD_KEYS_MAX;
-       unsigned j = i;
+       if (who<0) __pthread_rwlock_rdlock(&key_lock);
+       else if (!who) __pthread_rwlock_unlock(&key_lock);
+       else key_lock = (pthread_rwlock_t)PTHREAD_RWLOCK_INITIALIZER;
+}
+
+int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *))
+{
+       pthread_t self = __pthread_self();
 
-       __pthread_self_init();
+       /* This can only happen in the main thread before
+        * pthread_create has been called. */
+       if (!self->tsd) self->tsd = __pthread_tsd_main;
+
+       /* Purely a sentinel value since null means slot is free. */
        if (!dtor) dtor = nodtor;
+
+       __pthread_rwlock_wrlock(&key_lock);
+       pthread_key_t j = next_key;
        do {
-               if (!a_cas_p(keys+j, 0, (void *)dtor)) {
-                       *k = j;
+               if (!keys[j]) {
+                       keys[next_key = *k = j] = dtor;
+                       __pthread_rwlock_unlock(&key_lock);
                        return 0;
                }
-       } while ((j=(j+1)%PTHREAD_KEYS_MAX) != i);
+       } while ((j=(j+1)%PTHREAD_KEYS_MAX) != next_key);
+
+       __pthread_rwlock_unlock(&key_lock);
        return EAGAIN;
 }
 
-int pthread_key_delete(pthread_key_t k)
+int __pthread_key_delete(pthread_key_t k)
 {
+       sigset_t set;
+       pthread_t self = __pthread_self(), td=self;
+
+       __block_app_sigs(&set);
+       __pthread_rwlock_wrlock(&key_lock);
+
+       __tl_lock();
+       do td->tsd[k] = 0;
+       while ((td=td->next)!=self);
+       __tl_unlock();
+
        keys[k] = 0;
+
+       __pthread_rwlock_unlock(&key_lock);
+       __restore_sigs(&set);
+
        return 0;
 }
 
 void __pthread_tsd_run_dtors()
 {
        pthread_t self = __pthread_self();
-       int i, j, not_finished = self->tsd_used;
-       for (j=0; not_finished && j<PTHREAD_DESTRUCTOR_ITERATIONS; j++) {
-               not_finished = 0;
+       int i, j;
+       for (j=0; self->tsd_used && j<PTHREAD_DESTRUCTOR_ITERATIONS; j++) {
+               __pthread_rwlock_rdlock(&key_lock);
+               self->tsd_used = 0;
                for (i=0; i<PTHREAD_KEYS_MAX; i++) {
-                       if (self->tsd[i] && keys[i]) {
-                               void *tmp = self->tsd[i];
-                               self->tsd[i] = 0;
-                               keys[i](tmp);
-                               not_finished = 1;
+                       void *val = self->tsd[i];
+                       void (*dtor)(void *) = keys[i];
+                       self->tsd[i] = 0;
+                       if (val && dtor && dtor != nodtor) {
+                               __pthread_rwlock_unlock(&key_lock);
+                               dtor(val);
+                               __pthread_rwlock_rdlock(&key_lock);
                        }
                }
+               __pthread_rwlock_unlock(&key_lock);
        }
 }
+
+weak_alias(__pthread_key_create, pthread_key_create);
+weak_alias(__pthread_key_delete, pthread_key_delete);