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Commit 96fabbf5 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

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: default avatarOleg 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1bad95c3

kernel/exit.c

+4 −13
Original line number Original line Diff line number Diff line
@@ -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))

	if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))

	    && !(options & __WALL))

	    && !(options & __WALL))

		return 0;

		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);

	err = security_task_wait(p);

	if (err)

	if (err)
@@ -1497,10 +1491,9 @@ static long do_wait(pid_t pid, int options, struct siginfo __user *infop, 
	tsk = current;

	tsk = current;

	do {

	do {

		struct task_struct *p;

		struct task_struct *p;

		int ret;





		list_for_each_entry(p, &tsk->children, sibling) {

		list_for_each_entry(p, &tsk->children, sibling) {

			ret = eligible_child(pid, options, p);

			int ret = eligible_child(pid, options, p);

			if (!ret)

			if (!ret)

				continue;

				continue;
@@ -1524,19 +1517,17 @@ static long do_wait(pid_t pid, int options, struct siginfo __user *infop, 
				retval = wait_task_stopped(p,

				retval = wait_task_stopped(p,

						(options & WNOWAIT), infop,

						(options & WNOWAIT), infop,

						stat_addr, ru);

						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))

				if (!likely(options & WEXITED))

					continue;

					continue;

				retval = wait_task_zombie(p,

				retval = wait_task_zombie(p,

						(options & WNOWAIT), infop,

						(options & WNOWAIT), infop,

						stat_addr, ru);

						stat_addr, ru);

			} else if (p->exit_state != EXIT_DEAD) {

			} else if (p->exit_state != EXIT_DEAD) {

check_continued:

				/*

				/*

				 * It's running now, so it might later

				 * It's running now, so it might later

				 * exit, stop, or stop and then continue.

				 * exit, stop, or stop and then continue.