NPTL: Conditionalize asynchronous cancellation support on [SIGCANCEL].

ChangeLog

@@ -1,5 +1,10 @@
 2014-11-20  Roland McGrath  <roland@hack.frob.com>
 
+	* nptl/pthread_setcanceltype.c [!SIGCANCEL]: Return ENOTSUP early for
+	PTHREAD_CANCEL_ASYNCHRONOUS.
+	* nptl/pthread_cancel.c [!SIGCANCEL]: Just abort rather than trying to
+	send SIGCANCEL.
+
 	* nptl/default-sched.h: New file.
 	* sysdeps/unix/sysv/linux/default-sched.h: New file.
 	* nptl/pthread_create.c: Include it.

nptl/pthread_cancel.c

@@ -18,8 +18,9 @@
 
 #include <errno.h>
 #include <signal.h>
+#include <stdlib.h>
 #include "pthreadP.h"
-#include "atomic.h"
+#include <atomic.h>
 #include <sysdep.h>
 
 
@@ -63,6 +64,7 @@ pthread_cancel (th)
 						    oldval))
 	    goto again;
 
+#ifdef SIGCANCEL
 	  /* The cancellation handler will take care of marking the
 	     thread as canceled.  */
 	  INTERNAL_SYSCALL_DECL (err);
@@ -80,13 +82,20 @@ pthread_cancel (th)
 
 	  if (INTERNAL_SYSCALL_ERROR_P (val, err))
 	    result = INTERNAL_SYSCALL_ERRNO (val, err);
+#else
+          /* It should be impossible to get here at all, since
+             pthread_setcanceltype should never have allowed
+             PTHREAD_CANCEL_ASYNCHRONOUS to be set.  */
+          abort ();
+#endif
 
 	  break;
 	}
 
-	/* A single-threaded process should be able to kill itself, since there is
-	   nothing in the POSIX specification that says that it cannot.  So we set
-	   multiple_threads to true so that cancellation points get executed.  */
+	/* A single-threaded process should be able to kill itself, since
+	   there is nothing in the POSIX specification that says that it
+	   cannot.  So we set multiple_threads to true so that cancellation
+	   points get executed.  */
 	THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 	__pthread_multiple_threads = *__libc_multiple_threads_ptr = 1;

nptl/pthread_setcanceltype.c

@@ -26,12 +26,15 @@ __pthread_setcanceltype (type, oldtype)
      int type;
      int *oldtype;
 {
-  volatile struct pthread *self;
-
   if (type < PTHREAD_CANCEL_DEFERRED || type > PTHREAD_CANCEL_ASYNCHRONOUS)
     return EINVAL;
 
-  self = THREAD_SELF;
+#ifndef SIGCANCEL
+  if (type == PTHREAD_CANCEL_ASYNCHRONOUS)
+    return ENOTSUP;
+#endif
+
+  volatile struct pthread *self = THREAD_SELF;
 
   int oldval = THREAD_GETMEM (self, cancelhandling);
   while (1)