From nobody Wed Feb 11 06:30:14 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BCD59246BC5 for ; Wed, 8 Oct 2025 12:32:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759926746; cv=none; b=HLMbDVP1/4vYRV+mNPI4D+HLhozkyZ9zYGXf5NIgTyTfka4tqxW3xIYQaHVO0HfChIDpTQLL0pLZA5gG7CE5whld7JCpI1P0NgPJXWmLnlaI5H0nW6CauxlpH9GB3ci9WHT+T3ENPsKj8gi59mdkjMHqx0OKq522pSNtrqjcl90= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759926746; c=relaxed/simple; bh=rau0Of92Imxa/DTtgDTx+Cu0VrDp6j2EHky4cVJztmQ=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=ERaNeDJJ3iwDgGnTUvpRss5Vgd6H3y5/oKHvqGo5DtD9KWx94NfloLaxiGdWENAiVOp71v39/Kk3l0I36S/jhyh8KNljIRkVhAYqEsJxHMS2pzMYr8gHcRfo4BVPX0kA3hTFRfOaw0N+ipXZQmJDyZ7+kMrKhVg9A5NAW9zp+sY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=fNf2EpEh; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fNf2EpEh" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759926743; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to; bh=zbuIk8AUUnhPP+HZuAhozUptVNutr+rLH6yGzIfS3zI=; b=fNf2EpEhR1+8/PfJgJeqmxufq9pQEqxkMUqAtmOLEnclPx/atZn20X7K57q8jXU8AzFU0I aw8fymwMOmi3nVWtO3sMuzqIGOKzn/HdiyH2on5CyJG2ANXcyJbD6wJn7fhAl3nO24ysio 2HMvIJqKLLCA92xYU0Jgm4kjgeKrBDM= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-127-rmSgDHOlPuK4WyHm3pXA4w-1; Wed, 08 Oct 2025 08:32:20 -0400 X-MC-Unique: rmSgDHOlPuK4WyHm3pXA4w-1 X-Mimecast-MFC-AGG-ID: rmSgDHOlPuK4WyHm3pXA4w_1759926739 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 102DC19560AF; Wed, 8 Oct 2025 12:32:19 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.227.6]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 982151800452; Wed, 8 Oct 2025 12:32:14 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 8 Oct 2025 14:30:58 +0200 (CEST) Date: Wed, 8 Oct 2025 14:30:52 +0200 From: Oleg Nesterov To: Alexander Viro , Boqun Feng , David Howells , Ingo Molnar , Li RongQing , Linus Torvalds , Peter Zijlstra , Waiman Long , Will Deacon Cc: linux-kernel@vger.kernel.org Subject: [PATCH v2 2/4] seqlock: change thread_group_cputime() to use scoped_seqlock_read_irqsave() Message-ID: <20251008123052.GA20443@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20251008123014.GA20413@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" To simplify the code and make it more readable. While at it, change thread_group_cputime() to use __for_each_thread(sig). Signed-off-by: Oleg Nesterov --- kernel/sched/cputime.c | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-) diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 7097de2c8cda..94b445e947d2 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -315,8 +315,6 @@ void thread_group_cputime(struct task_struct *tsk, stru= ct task_cputime *times) struct signal_struct *sig =3D tsk->signal; u64 utime, stime; struct task_struct *t; - unsigned int seq, nextseq; - unsigned long flags; =20 /* * Update current task runtime to account pending time since last @@ -330,25 +328,18 @@ void thread_group_cputime(struct task_struct *tsk, st= ruct task_cputime *times) (void) task_sched_runtime(current); =20 rcu_read_lock(); - /* Attempt a lockless read on the first round. */ - nextseq =3D 0; - do { - seq =3D nextseq; - flags =3D read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq); + scoped_seqlock_read_irqsave(&sig->stats_lock) { times->utime =3D sig->utime; times->stime =3D sig->stime; times->sum_exec_runtime =3D sig->sum_sched_runtime; =20 - for_each_thread(tsk, t) { + __for_each_thread(sig, t) { task_cputime(t, &utime, &stime); times->utime +=3D utime; times->stime +=3D stime; times->sum_exec_runtime +=3D read_sum_exec_runtime(t); } - /* If lockless access failed, take the lock. */ - nextseq =3D 1; - } while (need_seqretry(&sig->stats_lock, seq)); - done_seqretry_irqrestore(&sig->stats_lock, seq, flags); + } rcu_read_unlock(); } =20 --=20 2.25.1.362.g51ebf55