another threads reliability fix: serialize writes to thr->threadsv

avoid most uses of PL_na (which is much more inefficient than a
simple local); update docs to suit; PL_na now being thr->Tna may
be a minor compatibility issue for extensions--will require dTHR
outside of XSUBs (those get automatic dTHR)

p4raw-id: //depot/perl@2387

1 files changed, 2 insertions, 1 deletions

diff --git a/doop.c b/doop.c
index 2a032d90c5..22495e6fa0 100644
--- a/doop.c
+++ b/doop.c
@@ -921,7 +921,8 @@ do_vop(I32 optype, SV *sv, SV *left, SV *right)
     len = leftlen < rightlen ? leftlen : rightlen;
     lensave = len;
     if (SvOK(sv) || SvTYPE(sv) > SVt_PVMG) {
-	dc = SvPV_force(sv, PL_na);
+	STRLEN n_a;
+	dc = SvPV_force(sv, n_a);
 	if (SvCUR(sv) < len) {
 	    dc = SvGROW(sv, len + 1);
 	    (void)memzero(dc + SvCUR(sv), len - SvCUR(sv) + 1);