Add a global variable called __isthreaded that can be tested throughout

libc to determine if locking is required. This is needed in libc
for use with kernel threads, but until a thread is created, we don't
really want to bother locking things. The variable was added here
because the crt code calls exit(main()) so all programs will get the
variable.

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/libc/stdlib/exit.c b/lib/libc/stdlib/exit.c
index a8f6e24..5df19dc 100644
--- a/lib/libc/stdlib/exit.c
+++ b/lib/libc/stdlib/exit.c
@@ -42,6 +42,15 @@ static char sccsid[] = "@(#)exit.c	8.1 (Berkeley) 6/4/93";
 void (*__cleanup)();
 
 /*
+ * This variable is zero until a process has created a thread.
+ * It is used to avoid calling locking functions in libc when they
+ * are not required. By default, libc is intended to be(come)
+ * thread-safe, but without a (significant) penalty to non-threaded
+ * processes.
+ */
+int	__isthreaded	= 0;
+
+/*
  * Exit, flushing stdio buffers if necessary.
  */
 void