Re: [PATCH v3] rfkill: Add rfkill-any LED trigger

From: "Michał Kępień" <kernel@kempniu.pl>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S . Miller" <davem@davemloft.net>,
	"Михаил Кринкин" <krinkin.m.u@gmail.com>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] rfkill: Add rfkill-any LED trigger
Date: Thu, 5 Jan 2017 15:36:54 +0100	[thread overview]
Message-ID: <20170105143654.GA21040@ozzy.nask.waw.pl> (raw)
In-Reply-To: <1483361523.21014.1.camel@sipsolutions.net>

> On Mon, 2017-01-02 at 13:21 +0100, Johannes Berg wrote:
> > > I'm not super happy with this conditional locking - can't we
> > > instead
> > > defer the necessary work to a workqueue, or so, for purposes of the
> > > LED?
> > 
> > Actually, since you can sleep in here, and do various other things
> > like scheduling etc. this can't even be correct as is - one thread
> > might be in the probe and another might also attempt to do some
> > operations that require the lock but now don't take it.
> 
> Additionally, this doesn't address the "can be called in any context"
> part, only the "even from within rfkill callbacks" part. It's clearly
> still not safe to call this from any context that is not allowed to
> sleep, for example.

Thanks for reviewing.  I will attempt a workqueue-based approach in v4.

-- 
Best regards,
Michał Kępień