From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Subject: Re: [RFC PATCH 00/18] kthreads/signal: Safer kthread API and signal
 handling
Date: Wed, 17 Jun 2015 04:34:50 -0700
Message-ID: <20150617113450.GA28508@infradead.org>
References: <1433516477-5153-1-git-send-email-pmladek@suse.cz>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Return-path: <linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Content-Disposition: inline
In-Reply-To: <1433516477-5153-1-git-send-email-pmladek-AlSwsSmVLrQ@public.gmane.org>
Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
To: Petr Mladek <pmladek-AlSwsSmVLrQ@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Richard Weinberger <richard-/L3Ra7n9ekc@public.gmane.org>, Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>, David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Trond Myklebust <trond.myklebust-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>, Anna Schumaker <anna.schumaker-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org>, linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Chris Mason <clm-b10kYP2dOMg@public.gmane.org>, "Paul E. McKenney" <paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Jiri Kosina <jkosina-AlSwsSmVLrQ@public.gmane.org>, Borislav Petkov <bp-l3A5Bk7waGM@public.gmane.org>, Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>, live-patching-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: linux-api@vger.kernel.org

On Fri, Jun 05, 2015 at 05:00:59PM +0200, Petr Mladek wrote:
> Kthreads are implemented as an infinite loop. They include check points
> for termination, freezer, parking, and even signal handling.
> 
> We need to touch all kthreads every time we want to add or
> modify the behavior of such checkpoints. It is not easy because
> there are several hundreds of kthreads and each of them is
> implemented in a slightly different way.
> 
> This anarchy brings potentially broken or non-standard behavior.
> For example, few kthreads already handle signals a strange way.
> 
> 
> This patchset is a _proof-of-concept_ how to improve the situation.

Maybe it might be a better idea to audit the existing callers of
signals for kthreads and first check if we can get rid of them.  Then
as a second step if any are left convert them to signalfd-style
operation where signals aren't checked synchronously but as something
the threads can consume on a as needed basis.
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html