[PATCH 121] ptrace_detach_task: don't use valid_signal()

[Oleg Nesterov]

ptrace_detach_task()->valid_signal() looks confusing.

Check sig >= 0 instead and add the comment.

---

 kernel/ptrace.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- PU/kernel/ptrace.c~121_COMMENT_VOLUNTARY    2009-10-26 03:05:58.000000000 
+0100
+++ PU/kernel/ptrace.c  2009-10-26 03:18:12.000000000 +0100
@@ -243,9 +243,13 @@ static void ptrace_wake_up(struct task_s
 
 static void ptrace_detach_task(struct task_struct *tracee, int sig)
 {
-       bool voluntary = valid_signal(sig);
-       enum utrace_resume_action action = UTRACE_DETACH;
+       /*
+        * If true, the caller is PTRACE_DETACH, otherwise
+        * the tracer detaches implicitly during exit.
+        */
+       bool voluntary = (sig >= 0);
        struct utrace_engine *engine = ptrace_lookup_engine(tracee);
+       enum utrace_resume_action action = UTRACE_DETACH;
 
        if (unlikely(IS_ERR(engine)))
                return;