From nobody Wed Dec 17 20:55:22 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 0B3601F936 for ; Sun, 5 Oct 2025 14:51:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759675919; cv=none; b=Lgz4LVTlJfGQPltco39verIwAIrdbUSmElq1+B7A0H0Y3M22UJcbk1QY8IMEDKdGHxyveeRbC9mHecjv0Ai9TT1CSlYEGH9PbmKfKFSUiaSbCe4DF6i4Z+NH4zAafcODcEQQJL3K1ZkP4/nzd2jpK/fT0V+uRvxgvqhreThpCxc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759675919; c=relaxed/simple; bh=SBpUcw9njwCcXX018ZZksLmhnkQo+yFEcYoPoFxZg1c=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=WCb1iaj+Iux3aEHhQlLyyYPdvt1dxollUsBZaP3ufbYVMVhCVTavGKQBQjdtmHpu/Hv50O2PAwFtyGgRWf/unVTML0oFVJ9A/xfPEgxfgSiUG+DoxbFKiPq8lq5d4WQf2Lsw6ZJzv7+xI58H/+cionEucppzZpjvbqV58ojMuXE= 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=X0/cVPQX; arc=none smtp.client-ip=170.10.133.124 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="X0/cVPQX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759675917; 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=d+nrIpiBElTNAUocY+50+3qKyPURcrFXkHy9MYXyToo=; b=X0/cVPQXObp0wLOguWalSuTMaaDeKv7s8Pi5iVqTR+NYLSmYRYmY/9zex/uUXTo2Ht6A1h t8fY1bBQ1MZwgUZfa371ycRKa82cj5r1ZSKJnNTKBG8WGlgVVDgwlS4LzK1CGYi2Z1Z5B8 bRPgiJIJnvkx3fRGU6q4pP8dsEfG3tE= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-618-m5vRQLcSOqWiyR-LqQBr8w-1; Sun, 05 Oct 2025 10:51:51 -0400 X-MC-Unique: m5vRQLcSOqWiyR-LqQBr8w-1 X-Mimecast-MFC-AGG-ID: m5vRQLcSOqWiyR-LqQBr8w_1759675910 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D3C6318004D4; Sun, 5 Oct 2025 14:51:49 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.5]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id C40E61956056; Sun, 5 Oct 2025 14:51:45 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sun, 5 Oct 2025 16:50:28 +0200 (CEST) Date: Sun, 5 Oct 2025 16:50:23 +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 2/5] seqlock: change thread_group_cputime() to use SEQLOCK_READ_SECTION() Message-ID: <20251005145023.GA1257@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: <20251005144929.GB1188@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 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 | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 7097de2c8cda..2d691075b6d6 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -315,7 +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 /* @@ -330,25 +329,18 @@ 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); + SEQLOCK_READ_SECTION(&sig->stats_lock, &flags) { 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