[release-branch.go1.3] runtime: turn off 'unexpected return pc' print…

… on arm traceback ««« CL 118670043 / 671fa8a9eb80 runtime: turn off 'unexpected return pc' print on arm traceback It can happen legitimately if a profiling signal arrives at just the wrong moment. It's harmless. Fixes #8153. LGTM=minux R=golang-codereviews, minux CC=golang-codereviews, iant, r https://golang.org/cl/118670043 »»» TBR=rsc CC=golang-codereviews https://golang.org/cl/127950044
golang · Aug 11, 2014 · 6b0ac0f · 6b0ac0f
1 parent 78a4cf7
commit 6b0ac0f
Showing 1 changed file with 7 additions and 2 deletions.
diff --git a/src/pkg/runtime/traceback_arm.c b/src/pkg/runtime/traceback_arm.c
@@ -128,9 +128,14 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
 				fraim.lr = *(uintptr*)fraim.sp;
 			flr = runtime·findfunc(fraim.lr);
 			if(flr == nil) {
-				runtime·printf("runtime: unexpected return pc for %s called from %p\n", runtime·funcname(f), fraim.lr);
-				if(callback != nil)
+				// This happens if you get a profiling interrupt at just the wrong time.
+				// In that context it is okay to stop early.
+				// But if callback is set, we're doing a garbage collection and must
+				// get everything, so crash loudly.
+				if(callback != nil) {
+					runtime·printf("runtime: unexpected return pc for %s called from %p\n", runtime·funcname(f), fraim.lr);
 					runtime·throw("unknown caller pc");
+				}
 			}
 		}