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 efc3804..39770c7 100644 (file)
--- a/src/thread/pthread_key_create.c
+++ b/src/thread/pthread_key_create.c
@@ -1,25 +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)
 {
-       static void (*keys[PTHREAD_KEYS_MAX])(void *);
-       int i = (uintptr_t)&k / 16 % PTHREAD_KEYS_MAX;
-       int j = i;
+}
 
-       libc.tsd_keys = keys;
+weak_alias(dummy_0, __tl_lock);
+weak_alias(dummy_0, __tl_unlock);
+
+void __pthread_key_atfork(int who)
+{
+       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();
+
+       /* 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;
-       /* Cheap trick - &k cannot match any destructor pointer */
-       while (a_cas_p(keys+j, 0, &k)
-               && (j=(j+1)%PTHREAD_KEYS_MAX) != i);
-       if (keys[j] != (void (*)(void *))&k)
-               return EAGAIN;
-       keys[j] = dtor;
-       *k = j;
+
+       __pthread_rwlock_wrlock(&key_lock);
+       pthread_key_t j = next_key;
+       do {
+               if (!keys[j]) {
+                       keys[next_key = *k = j] = dtor;
+                       __pthread_rwlock_unlock(&key_lock);
+                       return 0;
+               }
+       } while ((j=(j+1)%PTHREAD_KEYS_MAX) != next_key);
+
+       __pthread_rwlock_unlock(&key_lock);
+       return EAGAIN;
+}
+
+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;
+       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++) {
+                       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);