Any thoughts on this?
---------- Forwarded message ----------
Date: Fri, 23 Nov 2007 22:59:42 +0300
From: Oleg Nesterov <[EMAIL PROTECTED]>
To: Andrew Morton <[EMAIL PROTECTED]>
Cc: Eric Paris <[EMAIL PROTECTED]>, James Morris <[EMAIL PROTECTED]>,
Roland McGrath <[EMAIL PROTECTED]>, [EMAIL PROTECTED]
Subject: [PATCH -mm 2/2] do_wait: cleanup delay_group_leader() usage
eligible_child() == 2 means delay_group_leader(). With the previous patch this
only matters for EXIT_ZOMBIE task, we can move that special check to the only
place it is really needed.
Also, with this patch we don't skip security_task_wait() for the group leaders
in a non-empty thread group. I don't really understand the exact semantics of
security_task_wait(), but imho this change is a bugfix.
Also rearrange the code a bit to kill an ugly "check_continued" backdoor.
Signed-off-by: Oleg Nesterov <[EMAIL PROTECTED]>
--- PT/kernel/exit.c~6_delay_leader 2007-11-23 20:31:21.000000000 +0300
+++ PT/kernel/exit.c 2007-11-23 21:29:44.000000000 +0300
@@ -1137,12 +1137,6 @@ static int eligible_child(pid_t pid, int
if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
&& !(options & __WALL))
return 0;
- /*
- * Do not consider thread group leaders that are
- * in a non-empty thread group:
- */
- if (delay_group_leader(p))
- return 2;
err = security_task_wait(p);
if (err)
@@ -1494,10 +1488,9 @@ repeat:
tsk = current;
do {
struct task_struct *p;
- int ret;
list_for_each_entry(p, &tsk->children, sibling) {
- ret = eligible_child(pid, options, p);
+ int ret = eligible_child(pid, options, p);
if (!ret)
continue;
@@ -1521,19 +1514,17 @@ repeat:
retval = wait_task_stopped(p,
(options & WNOWAIT), infop,
stat_addr, ru);
- } else if (p->exit_state == EXIT_ZOMBIE) {
+ } else if (p->exit_state == EXIT_ZOMBIE &&
+ !delay_group_leader(p)) {
/*
- * Eligible but we cannot release it yet:
+ * We don't reap group leaders with subthreads.
*/
- if (ret == 2)
- goto check_continued;
if (!likely(options & WEXITED))
continue;
retval = wait_task_zombie(p,
(options & WNOWAIT), infop,
stat_addr, ru);
} else if (p->exit_state != EXIT_DEAD) {
-check_continued:
/*
* It's running now, so it might later
* exit, stop, or stop and then continue.
-
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