various fixes for race conditions under threads: mutex locks based

on PL_threadnum were seriously flawed, since it means more than one
thread could enter the critical region; PL_na was global instead of
thread-local; child thread could finish and free thr structures
before Thread->new() got around to creating the Thread object;
cv_clone() needed locking, as it mucks with PL_comppad and other
global data; new_struct_thread() needed to lock template-thread's
mutex while copying its data

p4raw-id: //depot/perl@2385

1 files changed, 1 insertions, 2 deletions

diff --git a/pp_hot.c b/pp_hot.c
index 9b1791df5e..733b6b00f3 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -2170,8 +2170,7 @@ PP(pp_entersub)
      	 * (3) instead of (2) so we'd have to clone. Would the fact
      	 * that we released the mutex more quickly make up for this?
      	 */
-	if (PL_threadnum &&
-	    (svp = hv_fetch(thr->cvcache, (char *)cv, sizeof(cv), FALSE)))
+	if ((svp = hv_fetch(thr->cvcache, (char *)cv, sizeof(cv), FALSE)))
 	{
 	    /* We already have a clone to use */
 	    MUTEX_UNLOCK(CvMUTEXP(cv));