avoid using signals when a thread attempts to cancel itself

not only is pthread_kill expensive in this case; it also breaks
testing under qemu app-level emulation.

diff --git a/src/thread/pthread_cancel.c b/src/thread/pthread_cancel.c
index a21c386697c3e399c6c86e18d6be56c77a05d284..3d229223ed1b00f622c3319b7cfa327086f530d7 100644 (file)
--- a/src/thread/pthread_cancel.c
+++ b/src/thread/pthread_cancel.c
@@ -92,5 +92,6 @@ int pthread_cancel(pthread_t t)
                init = 1;
        }
        a_store(&t->cancel, 1);
+       if (t == pthread_self() && !t->cancelasync) return 0;
        return pthread_kill(t, SIGCANCEL);
 }