If register_uprobe() or register_uretprobe() fails while attempting to
register a probe on a process that already has one or more u[ret]probes
in place, subsequent uprobes activity on that process (probe hits,
register/unregister attempts) may hang.  Here's a fix.

---

 kernel/uprobes.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff -puN kernel/uprobes.c~reused-probe-fix kernel/uprobes.c
--- linux-2.6.21-rc6/kernel/uprobes.c~reused-probe-fix	2007-07-06 09:16:49.000000000 -0700
+++ linux-2.6.21-rc6-jimk/kernel/uprobes.c	2007-07-06 09:18:56.000000000 -0700
@@ -830,8 +830,10 @@ fail_uproc:
 	if (uproc_is_new) {
 		uprobe_free_process(uproc);
 		mutex_unlock(&uproc_mutex);
-	} else
+	} else {
+		up_write(&uproc->rwsem);
 		uprobe_put_process(uproc);
+	}
 
 fail_tsk:
 	put_task_struct(p);
_