From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-fsdevel-owner@vger.kernel.org>
Received: from mail.linuxfoundation.org ([140.211.169.12]:43978 "EHLO
        mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1731193AbeGRDOP (ORCPT
        <rfc822;linux-fsdevel@vger.kernel.org>);
        Tue, 17 Jul 2018 23:14:15 -0400
Date: Tue, 17 Jul 2018 19:38:41 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Omar Sandoval <osandov@osandov.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Eric Biederman <ebiederm@xmission.com>,
        James Morse <james.morse@arm.com>,
        Bhupesh Sharma <bhsharma@redhat.com>, kernel-team@fb.com
Subject: Re: [PATCH v2 2/7] proc/kcore: replace kclist_lock rwlock with
 rwsem
Message-Id: <20180717193841.271d1c57b6f88d75c83892be@linux-foundation.org>
In-Reply-To: <783ba3becc424db45e5d5c93559fc40ef6173f01.1531440458.git.osandov@fb.com>
References: <cover.1531440458.git.osandov@fb.com>
        <783ba3becc424db45e5d5c93559fc40ef6173f01.1531440458.git.osandov@fb.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <linux-fsdevel.vger.kernel.org>

On Thu, 12 Jul 2018 17:09:34 -0700 Omar Sandoval <osandov@osandov.com> wrote:

> From: Omar Sandoval <osandov@fb.com>
> 
> Now we only need kclist_lock from user context and at fs init time, and
> the following changes need to sleep while holding the kclist_lock.
> 
> ...
>
> --- a/fs/proc/kcore.c
> +++ b/fs/proc/kcore.c
> @@ -59,8 +59,8 @@ struct memelfnote
>  };
>  
>  static LIST_HEAD(kclist_head);
> -static DEFINE_RWLOCK(kclist_lock);
> -static int kcore_need_update = 1;
> +static DECLARE_RWSEM(kclist_lock);
> +static atomic_t kcore_need_update = ATOMIC_INIT(1);

It's unclear why kcore_need_update was changed to atomic_t - it's still
updated under kclist_lock?

Maybe it's for a later patch.