runtime: fix bad status throw

when garbage collector sees recovering goroutine

Fixes issue 711.

R=r
CC=golang-dev
http://codereview.appspot.com/869045

1 files changed, 6 insertions, 3 deletions

diff --git a/src/pkg/runtime/proc.c b/src/pkg/runtime/proc.c
index 454a4a217..1a1895dcb 100644
--- a/src/pkg/runtime/proc.c
+++ b/src/pkg/runtime/proc.c
@@ -461,9 +461,7 @@ scheduler(void)
 			
 			// unwind to the stack frame with d->sp in it.
 			unwindstack(gp, d->sp);
-			if(d->sp < gp->stackguard || gp->stackbase < d->sp)
-				throw("bad stack in recovery");
-			
+
 			// make the deferproc for this d return again,
 			// this time returning 1.  function will jump to
 			// standard return epilogue.
@@ -930,6 +928,11 @@ unwindstack(G *gp, byte *sp)
 		gp->stackguard = top->stackguard;
 		free(stk);
 	}
+
+	if(sp != nil && (sp < gp->stackguard - StackGuard || gp->stackbase < sp)) {
+		printf("recover: %p not in [%p, %p]\n", sp, gp->stackguard - StackGuard, gp->stackbase);
+		throw("bad unwindstack");
+	}
 }
 
 static void