remove __lock dependency from exit

there's no sense in using a powerful lock in exit, because it will
never be unlocked. a thread that arrives at exit while exit is already
in progress just needs to hang forever. use the pause syscall for this
because it's cheap and easy and universally available.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/exit/exit.c b/src/exit/exit.c
index ae557c09..fc291484 100644
--- a/src/exit/exit.c
+++ b/src/exit/exit.c
@@ -2,6 +2,8 @@
 #include <unistd.h>
 #include <stdio.h>
 #include "libc.h"
+#include "atomic.h"
+#include "syscall.h"
 
 static void dummy()
 {
@@ -13,10 +15,10 @@ weak_alias(dummy, __fflush_on_exit);
 
 void exit(int code)
 {
-	static int lock[2];
+	static int lock;
 
 	/* If more than one thread calls exit, hang until _Exit ends it all */
-	LOCK(lock);
+	while (a_swap(&lock, 1)) __syscall(SYS_pause);
 
 	/* Only do atexit & stdio flush if they were actually used */
 	__funcs_on_exit();