From nobody Wed Dec 17 21:11:34 2025 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 93D1228C00D for ; Sun, 5 Oct 2025 14:52:01 +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=1759675923; cv=none; b=YkXVbOYwLRhxbr3QX+akuYsT3ddcpDdLXvC9Po3XQYnZyPd2ZtYQ2+ucnvsHt66rKCQZpB9zR1nAvwb/5z66xCsuZZGArmVAw+PqK+zIm0WlP0b/k1Ap8r+Z9GSIO/QUoORvNoY3VqvIWbDWej4Wijcn23rAy2v/kF0MmM3I7Fw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759675923; c=relaxed/simple; bh=buwnXEzaY/kB7xqjt5XcN5g7He6rfczFJlP2htMe0QQ=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=Gho5LACYt9g4Mi1FJgcAgc8gOV5hhkyu0Hd7ivsOuUZ8o8x3u8kwnurav1fDUOWh+vQ0gN8m0U4Na2Ttt+0FGqesifqwbUSaC3stoiM3+mo5TDeb8sH0NnLxHyJ81b2b8C8LDhHQMhAs8p4ysKcSSQy/wh1+VfIZiScAFMgloPE= 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=JpnuQgIX; 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="JpnuQgIX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759675920; 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=zdv/QBAv/KWiiKvJ9bn4POQBwt628tnn7lG3kzkJLMg=; b=JpnuQgIX8ZgPoe96f+ODMJOVAXAyKlcC2EVrEhmbD8+OESoJgnsNz78S6TUnW8mbDPNrts 0hTJseZLuagCCtpGy53AxXw+/1RKOO9mCkC9EwSVHp/aZNOUCKOmm7DjlrAS6icXIbVkvF gz/KzW+SZD+FwL9FaWQoU6HjrQ34YPU= Received: from mx-prod-mc-01.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-147-_8Ayc0FPOyOyMbvZyTshBA-1; Sun, 05 Oct 2025 10:51:57 -0400 X-MC-Unique: _8Ayc0FPOyOyMbvZyTshBA-1 X-Mimecast-MFC-AGG-ID: _8Ayc0FPOyOyMbvZyTshBA_1759675916 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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C4BF1195608B; Sun, 5 Oct 2025 14:51:55 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.5]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id D8EF81800447; Sun, 5 Oct 2025 14:51:51 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sun, 5 Oct 2025 16:50:34 +0200 (CEST) Date: Sun, 5 Oct 2025 16:50:29 +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 3/5] seqlock: change do_task_stat() to use SEQLOCK_READ_SECTION() Message-ID: <20251005145029.GA1260@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 3.4.1 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. Signed-off-by: Oleg Nesterov --- fs/proc/array.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index d6a0369caa93..99bcaa58a2bd 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -483,7 +483,6 @@ static int do_task_stat(struct seq_file *m, struct pid_= namespace *ns, unsigned long flags; int exit_code =3D task->exit_code; struct signal_struct *sig =3D task->signal; - unsigned int seq =3D 1; =20 state =3D *get_task_state(task); vsize =3D eip =3D esp =3D 0; @@ -540,10 +539,7 @@ static int do_task_stat(struct seq_file *m, struct pid= _namespace *ns, if (permitted && (!whole || num_threads < 2)) wchan =3D !task_is_running(task); =20 - do { - seq++; /* 2 on the 1st/lockless path, otherwise odd */ - flags =3D read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq); - + SEQLOCK_READ_SECTION(&sig->stats_lock, &flags) { cmin_flt =3D sig->cmin_flt; cmaj_flt =3D sig->cmaj_flt; cutime =3D sig->cutime; @@ -565,8 +561,7 @@ static int do_task_stat(struct seq_file *m, struct pid_= namespace *ns, } rcu_read_unlock(); } - } while (need_seqretry(&sig->stats_lock, seq)); - done_seqretry_irqrestore(&sig->stats_lock, seq, flags); + } =20 if (whole) { thread_group_cputime_adjusted(task, &utime, &stime); --=20 2.25.1.362.g51ebf55