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do_wait: cleanup delay_group_leader() usage

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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 <oleg@tv-sign.ru>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2008-02-08 04:19:04 -08:00 committed by Linus Torvalds
parent 1bad95c3be
commit 96fabbf55a
1 changed files with 4 additions and 13 deletions
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17
kernel/exit.c
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@ -1140,12 +1140,6 @@ static int eligible_child(pid_t pid, int options, struct task_struct *p)
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)
@ -1497,10 +1491,9 @@ static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
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;
@ -1524,19 +1517,17 @@ static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
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.