runtime: co-exist with NPTL's pthread_cancel.

NPTL uses SIGRTMIN (signal 32) to effect thread cancellation.
Go's runtime replaces NPTL's signal handler with its own, and
ends up aborting if a C library that ends up calling
pthread_cancel is used.

This patch prevents runtime from replacing NPTL's handler.

Fixes #6997.

R=golang-codereviews, iant, dvyukov
CC=golang-codereviews
https://golang.org/cl/47540043

diff --git a/misc/cgo/test/cgo_linux_test.go b/misc/cgo/test/cgo_linux_test.go
index 056d67c96a9280570e623f792f527b8d3b79a9bc..0a405c7a3b9d4d08516f79b481a2f9ea290fc596 100644 (file)
--- a/misc/cgo/test/cgo_linux_test.go
+++ b/misc/cgo/test/cgo_linux_test.go
@@ -7,3 +7,4 @@ package cgotest
 import "testing"
 
 func TestSetgid(t *testing.T) { testSetgid(t) }
+func Test6997(t *testing.T)   { test6997(t) }

diff --git a/misc/cgo/test/issue6997_linux.c b/misc/cgo/test/issue6997_linux.c
new file mode 100644 (file)
index 0000000..897cdd0
--- /dev/null
+++ b/misc/cgo/test/issue6997_linux.c
@@ -0,0 +1,26 @@
+// Copyright 2014 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 <pthread.h>
+#include <stdio.h>
+#include <unistd.h>
+
+static pthread_t thread;
+
+static void* threadfunc(void* dummy) {
+       while(1) {
+               sleep(1);
+       }
+}
+
+int StartThread() {
+       return pthread_create(&thread, NULL, &threadfunc, NULL);
+}
+
+int CancelThread() {
+       void *r;
+       pthread_cancel(thread);
+       pthread_join(thread, &r);
+       return (r == PTHREAD_CANCELED);
+}

diff --git a/misc/cgo/test/issue6997_linux.go b/misc/cgo/test/issue6997_linux.go
new file mode 100644 (file)
index 0000000..871bd51
--- /dev/null
+++ b/misc/cgo/test/issue6997_linux.go
@@ -0,0 +1,40 @@
+// Copyright 2014 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.
+
+// Test that pthread_cancel works as expected
+// (NPTL uses SIGRTMIN to implement thread cancellation)
+// See http://golang.org/issue/6997
+package cgotest
+
+/*
+#cgo CFLAGS: -pthread
+#cgo LDFLAGS: -pthread
+extern int StartThread();
+extern int CancelThread();
+*/
+import "C"
+
+import "testing"
+import "time"
+
+func test6997(t *testing.T) {
+       r := C.StartThread()
+       if r != 0 {
+               t.Error("pthread_create failed")
+       }
+       c := make(chan C.int)
+       go func() {
+               time.Sleep(500 * time.Millisecond)
+               c <- C.CancelThread()
+       }()
+
+       select {
+       case r = <-c:
+               if r == 0 {
+                       t.Error("pthread finished but wasn't cancelled??")
+               }
+       case <-time.After(5 * time.Second):
+               t.Error("hung in pthread_cancel/pthread_join")
+       }
+}

diff --git a/src/pkg/runtime/signals_linux.h b/src/pkg/runtime/signals_linux.h
index 9c356700759fae5cc88830ae73fe1ef1e29625f1..368afc1c841b267d46e1f7fdfb7470cee2b43874 100644 (file)
--- a/src/pkg/runtime/signals_linux.h
+++ b/src/pkg/runtime/signals_linux.h
@@ -41,7 +41,7 @@ SigTab runtime·sigtab[] = {
        /* 29 */        N, "SIGIO: i/o now possible",
        /* 30 */        N, "SIGPWR: power failure restart",
        /* 31 */        N, "SIGSYS: bad system call",
-       /* 32 */        N, "signal 32",
+       /* 32 */        0, "signal 32", /* SIGCANCEL; see issue 6997 */
        /* 33 */        0, "signal 33", /* SIGSETXID; see issue 3871 */
        /* 34 */        N, "signal 34",
        /* 35 */        N, "signal 35",