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 e26f199..39770c7 100644 (file)
--- a/src/thread/pthread_key_create.c
+++ b/src/thread/pthread_key_create.c
@@ -1,4 +1,5 @@
 #include "pthread_impl.h"
+#include "fork_impl.h"
 
 volatile size_t __pthread_tsd_size = sizeof(void *) * PTHREAD_KEYS_MAX;
 void *__pthread_tsd_main[PTHREAD_KEYS_MAX] = { 0 };
@@ -13,43 +14,23 @@ static void nodtor(void *dummy)
 {
 }
 
-static void dirty(void *dummy)
+static void dummy_0(void)
 {
 }
 
-struct cleanup_args {
-       pthread_t caller;
-       int ret;
-};
+weak_alias(dummy_0, __tl_lock);
+weak_alias(dummy_0, __tl_unlock);
 
-static void clean_dirty_tsd_callback(void *p)
+void __pthread_key_atfork(int who)
 {
-       struct cleanup_args *args = p;
-       pthread_t self = __pthread_self();
-       pthread_key_t i;
-       for (i=0; i<PTHREAD_KEYS_MAX; i++) {
-               if (keys[i] == dirty && self->tsd[i])
-                       self->tsd[i] = 0;
-       }
-       /* Arbitrary choice to avoid data race. */
-       if (args->caller == self) args->ret = 0;
-}
-
-static int clean_dirty_tsd(void)
-{
-       struct cleanup_args args = {
-               .caller = __pthread_self(),
-               .ret = EAGAIN
-       };
-       __pthread_key_delete_synccall(clean_dirty_tsd_callback, &args);
-       return args.ret;
+       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_key_t j = next_key;
        pthread_t self = __pthread_self();
-       int found_dirty = 0;
 
        /* This can only happen in the main thread before
         * pthread_create has been called. */
@@ -58,46 +39,38 @@ int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *))
        /* Purely a sentinel value since null means slot is free. */
        if (!dtor) dtor = nodtor;
 
-       pthread_rwlock_wrlock(&key_lock);
+       __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);
+                       __pthread_rwlock_unlock(&key_lock);
                        return 0;
-               } else if (keys[j] == dirty) {
-                       found_dirty = 1;
                }
        } while ((j=(j+1)%PTHREAD_KEYS_MAX) != next_key);
 
-       /* It's possible that all slots are in use or __synccall fails. */
-       if (!found_dirty || clean_dirty_tsd()) {
-               pthread_rwlock_unlock(&key_lock);
-               return EAGAIN;
-       }
-
-       /* If this point is reached there is necessarily a newly-cleaned
-        * slot to allocate to satisfy the caller's request. Find it and
-        * mark any additional previously-dirty slots clean. */
-       for (j=0; j<PTHREAD_KEYS_MAX; j++) {
-               if (keys[j] == dirty) {
-                       if (dtor) {
-                               keys[next_key = *k = j] = dtor;
-                               dtor = 0;
-                       } else {
-                               keys[j] = 0;
-                       }
-               }
-       }
-
-       pthread_rwlock_unlock(&key_lock);
-       return 0;
+       __pthread_rwlock_unlock(&key_lock);
+       return EAGAIN;
 }
 
-int __pthread_key_delete_impl(pthread_key_t k)
+int __pthread_key_delete(pthread_key_t k)
 {
-       pthread_rwlock_wrlock(&key_lock);
-       keys[k] = dirty;
-       pthread_rwlock_unlock(&key_lock);
+       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;
 }
 
@@ -106,20 +79,21 @@ 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);
+               __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 && dtor != dirty) {
-                               pthread_rwlock_unlock(&key_lock);
+                       if (val && dtor && dtor != nodtor) {
+                               __pthread_rwlock_unlock(&key_lock);
                                dtor(val);
-                               pthread_rwlock_rdlock(&key_lock);
+                               __pthread_rwlock_rdlock(&key_lock);
                        }
                }
-               pthread_rwlock_unlock(&key_lock);
+               __pthread_rwlock_unlock(&key_lock);
        }
 }
 
 weak_alias(__pthread_key_create, pthread_key_create);
+weak_alias(__pthread_key_delete, pthread_key_delete);