prevent code from running under a thread id which already gave ESRCH

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index cf9cb191a52f80abbf43003fe253ea640d7cb232..6e49acdc6bb77389de220d2b91e2227702b8b626 100644 (file)
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -30,7 +30,6 @@ _Noreturn void pthread_exit(void *result)
        /* Mark this thread dead before decrementing count */
        __lock(self->killlock);
        self->dead = 1;
-       __unlock(self->killlock);
 
        /* Block all signals before decrementing the live thread count.
         * This is important to ensure that dynamically allocated TLS
@@ -38,6 +37,13 @@ _Noreturn void pthread_exit(void *result)
         * reasons as well. */
        __syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGALL_SET, &set, _NSIG/8);
 
+       /* Wait to unlock the kill lock, which governs functions like
+        * pthread_kill which target a thread id, until signals have
+        * been blocked. This precludes observation of the thread id
+        * as a live thread (with application code running in it) after
+        * the thread was reported dead by ESRCH being returned. */
+       __unlock(self->killlock);
+
        /* It's impossible to determine whether this is "the last thread"
         * until performing the atomic decrement, since multiple threads
         * could exit at the same time. For the last thread, revert the