linux-kernel - Re: [RFC][PATCH] dm: Remove dm_bufio_cond

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160923092658.GA24285@gmail.com>
Date:   Fri, 23 Sep 2016 11:26:58 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Mikulas Patocka <mpatocka@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>,
        Alasdair Kergon <agk@...hat.com>, linux-kernel@...r.kernel.org,
        dm-devel@...hat.com, Joe Thornber <ejt@...hat.com>
Subject: Re: [RFC][PATCH] dm: Remove dm_bufio_cond_resched()


* Thomas Gleixner <tglx@...utronix.de> wrote:

> On Fri, 23 Sep 2016, Peter Zijlstra wrote:
> > On Fri, Sep 23, 2016 at 10:00:37AM +0200, Thomas Gleixner wrote:
> > > On Fri, 23 Sep 2016, Peter Zijlstra wrote:
> > > > It is, might_sleep() implies might_resched(). In fact, that's all what
> > > > PREEMPT_VOLUNTARY is, make the might_sleep() debug test imply a resched
> > > > point.
> > > 
> > > Grr, how intuitive - NOT!
> > 
> > No, it actually makes sense. Because you 'obviously' only call
> > might_sleep() in contexts that should be able to sleep (if not, it'll
> > holler). So they're already placed right for preemption.
> 
> I disagree. might_sleep() is commonly known as a debug mechanism and it
> existed before the preemption stuff went in. So the easy way to sprinkle
> preemption points into the kernel was to hijack might_sleep(). I know it's
> historical, but that doesnt make it any more intuitive.

If we rename it to might_as_well_sleep() it becomes more intuitive! ;-)

Thanks,

	Ingo