From patchwork Wed Jul 28 14:32:28 2010
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Subject: [gccgo] Avoid race condition
From: Ian Taylor <iant@google.com>
X-Patchwork-Id: 60148
Message-Id: <mcriq3zn0cj.fsf@google.com>
To: gcc-patches@gcc.gnu.org, gofrontend-dev@googlegroups.com
Date: Wed, 28 Jul 2010 07:32:28 -0700

I copied this patch from the other Go library to avoid a race condition
which gccgo tends to trigger when running the tests.  I didn't want to
take the time to do a full library upgrade right now.  Committed to
gccgo branch.

Ian


diff -r 18be60ce1a6e libgo/go/io/pipe.go
--- a/libgo/go/io/pipe.go	Wed Jul 28 06:47:29 2010 -0700
+++ b/libgo/go/io/pipe.go	Wed Jul 28 07:30:40 2010 -0700
@@ -52,6 +52,13 @@
 		case <-p.done:
 			if ndone++; ndone == 2 {
 				// both reader and writer are gone
+				// close out any existing i/o
+				if r1 == nil {
+					p.r2 <- pipeResult{0, os.EINVAL}
+				}
+				if w1 == nil {
+					p.w2 <- pipeResult{0, os.EINVAL}
+				}
 				return
 			}
 			continue
@@ -89,6 +96,11 @@
 				p.r2 <- pipeResult{0, werr}
 				continue
 			}
+			if rerr != nil {
+				// read end is closed
+				p.r2 <- pipeResult{0, os.EINVAL}
+				continue
+			}
 			r1 = nil // disable Read until this one is done
 		case wb = <-w1:
 			if rerr != nil {
@@ -96,6 +108,11 @@
 				p.w2 <- pipeResult{0, rerr}
 				continue
 			}
+			if werr != nil {
+				// write end is closed
+				p.w2 <- pipeResult{0, os.EINVAL}
+				continue
+			}
 			w1 = nil // disable Write until this one is done
 		}