Re: [PATCH] -mm check_rlimit oops on p->signal

[Andrew Morton <akpm@osdl.org>]

Hugh Dickins <hugh@veritas.com> wrote:
>
> +	if (likely(p->signal && p->exit_state < EXIT_ZOMBIE)) {

Worried.  This places an ordering interpretation on TASK_* and EXIT_* which
AFAIK hadn't been there beforehand.  If someone later comes along and adds

#define TASK_DOODLING 64

then we lose.

I wonder if for clarity and future-safety we should do something like:

--- 25/include/linux/sched.h~task-exit_state-clarity	Mon Nov 15 15:40:24 2004
+++ 25-akpm/include/linux/sched.h	Mon Nov 15 15:42:40 2004
@@ -105,13 +105,20 @@ extern unsigned long nr_iowait(void);
 
 #include <asm/processor.h>
 
+/*
+ * Tasks whose exit_state is less that TASK_EXIT_MARKER are considered to
+ * be still running.  Tasks whose exit_state is greater than TASK_EXIT_MARKER
+ * are in the process of exitting.  TASK_EXIT_MARKER is never actually set in
+ * task_struct.exit_state.
+ */
 #define TASK_RUNNING		0
 #define TASK_INTERRUPTIBLE	1
 #define TASK_UNINTERRUPTIBLE	2
 #define TASK_STOPPED		4
 #define TASK_TRACED		8
-#define EXIT_ZOMBIE		16
-#define EXIT_DEAD		32
+#define TASK_EXIT_MARKER	16	
+#define EXIT_ZOMBIE		32
+#define EXIT_DEAD		64
 
 #define __set_task_state(tsk, state_value)		\
 	do { (tsk)->state = (state_value); } while (0)
_

It seems a bit dorky for some reason...