runtime: fix integer comparison in signal handling

(sig is unsigned, so sig-1 >= 0 is always true.)

Fixes #11281.

Change-Id: I4b9d784da6e3cc80816f2d2f7228d5d8a237e2d5
Reviewed-on: https://go-review.googlesource.com/17457
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/runtime/signal1_unix.go b/src/runtime/signal1_unix.go
index 3a8b5ba4607863737bacb164f75bc78b1c30db47..405713b371159198fe89b00855922690310c8e81 100644 (file)
--- a/src/runtime/signal1_unix.go
+++ b/src/runtime/signal1_unix.go
@@ -228,11 +228,11 @@ func ensureSigM() {
                for {
                        select {
                        case sig := <-enableSigChan:
-                               if b := sig - 1; b >= 0 {
+                               if b := sig - 1; sig > 0 {
                                        sigBlocked[b/32] &^= (1 << (b & 31))
                                }
                        case sig := <-disableSigChan:
-                               if b := sig - 1; b >= 0 {
+                               if b := sig - 1; sig > 0 {
                                        sigBlocked[b/32] |= (1 << (b & 31))
                                }
                        }