Commit c1be35a1 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Andrew Morton
Browse files

exit: wait_task_zombie: kill the no longer necessary spin_lock_irq(siglock) 

After the recent changes nobody use siglock to read the values protected
by stats_lock, we can kill spin_lock_irq(&current->sighand->siglock) and
update the comment.

With this patch only __exit_signal() and thread_group_start_cputime() take
stats_lock under siglock.

Link: https://lkml.kernel.org/r/20240123153359.GA21866@redhat.com


Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarDylan Hatch <dylanbhatch@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7601df80

kernel/exit.c

+3 −7
Original line number Diff line number Diff line
@@ -1127,17 +1127,14 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 
		 * and nobody can change them.

		 *

		 * psig->stats_lock also protects us from our sub-threads

		 * which can reap other children at the same time. Until

		 * we change k_getrusage()-like users to rely on this lock

		 * we have to take ->siglock as well.

		 * which can reap other children at the same time.

		 *

		 * We use thread_group_cputime_adjusted() to get times for

		 * the thread group, which consolidates times for all threads

		 * in the group including the group leader.

		 */

		thread_group_cputime_adjusted(p, &tgutime, &tgstime);

		spin_lock_irq(&current->sighand->siglock);

		write_seqlock(&psig->stats_lock);

		write_seqlock_irq(&psig->stats_lock);

		psig->cutime += tgutime + sig->cutime;

		psig->cstime += tgstime + sig->cstime;

		psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
@@ -1160,8 +1157,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 
			psig->cmaxrss = maxrss;

		task_io_accounting_add(&psig->ioac, &p->ioac);

		task_io_accounting_add(&psig->ioac, &sig->ioac);

		write_sequnlock(&psig->stats_lock);

		spin_unlock_irq(&current->sighand->siglock);

		write_sequnlock_irq(&psig->stats_lock);

	}



	if (wo->wo_rusage)