code review 8454043: runtime: reset dangling typed pointer

src/pkg/runtime/proc.c

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
 #include "arch_GOARCH.h"
 #include "malloc.h"
 #include "stack.h"
 #include "race.h"
 #include "type.h"
@@ skipping 1160 matching lines @@
 // runtime·park continuation on g0.
 static void
 park0(G *gp)
 {
         gp->status = Gwaiting;
         gp->m = nil;
         m->curg = nil;
         if(m->waitunlockf) {
                 m->waitunlockf(m->waitlock);
                 m->waitunlockf = nil;
+                m->waitlock = nil;
         }
         if(m->lockedg) {
                 stoplockedm();
                 execute(gp);  // Never returns.
         }
         schedule();
 }
 
 // Scheduler yield.
 void
@@ skipping 1156 matching lines @@
                         }
                 }
                 if(s != i/2 && s != i/2+1) {
                         runtime·printf("bad steal %d, want %d or %d, iter %d\n",
                                 s, i/2, i/2+1, i);
                         runtime·throw("bad steal");
                 }
         }
 }