pipe - fix UP build error.

Reported-by: Hasso Tepper <hasso@estpak.ee>

diff --git a/sys/kern/sys_pipe.c b/sys/kern/sys_pipe.c
index 21ee2c0..c98825b 100644 (file)
--- a/sys/kern/sys_pipe.c
+++ b/sys/kern/sys_pipe.c
@@ -789,20 +789,22 @@ pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
                        if (segsize > space)
                                segsize = space;
 
+#ifdef SMP
                        /*
                         * If this is the first loop and the reader is
                         * blocked, do a preemptive wakeup of the reader.
                         *
-                        * This works for both SMP and UP.  On SMP the IPI
-                        * latency plus the wlock interlock on the reader
-                        * side is the fastest way to get the reader going.
-                        * (The scheduler will hard loop on lock tokens).
+                        * On SMP the IPI latency plus the wlock interlock
+                        * on the reader side is the fastest way to get the
+                        * reader going.  (The scheduler will hard loop on
+                        * lock tokens).
                         *
                         * NOTE: We can't clear WANTR here without acquiring
                         * the rlock, which we don't want to do here!
                         */
                        if ((wpipe->pipe_state & PIPE_WANTR) && pipe_mpsafe > 1)
                                wakeup(wpipe);
+#endif
 
                        /*
                         * Transfer segment, which may include a wrap-around.