From 59f88d766263344ce3e124d969ba66720aff4590 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 21 Mar 2019 13:58:12 -0400 Subject: [PATCH] fix data race choosing next key slot in pthread_key_create commit 84d061d5a31c9c773e29e1e2b1ffe8cb9557bc58 wrongly moved the access to the global next_key outside of the scope of the lock. the error manifested as spurious failure to find an available key slot under concurrent calls to pthread_key_create, since the stopping condition could be met after only a small number of slots were examined. --- src/thread/pthread_key_create.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/thread/pthread_key_create.c b/src/thread/pthread_key_create.c index 210605c6..d1120941 100644 --- a/src/thread/pthread_key_create.c +++ b/src/thread/pthread_key_create.c @@ -22,7 +22,6 @@ weak_alias(dummy_0, __tl_unlock); int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *)) { - pthread_key_t j = next_key; pthread_t self = __pthread_self(); /* This can only happen in the main thread before @@ -33,6 +32,7 @@ int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *)) if (!dtor) dtor = nodtor; __pthread_rwlock_wrlock(&key_lock); + pthread_key_t j = next_key; do { if (!keys[j]) { keys[next_key = *k = j] = dtor; -- 2.25.1