linux-kernel - Re: [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time

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: <20190906101819-mutt-send-email-mst@kernel.org>
Date:   Fri, 6 Sep 2019 10:18:49 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Vivek Goyal <vgoyal@...hat.com>
Cc:     Stefan Hajnoczi <stefanha@...hat.com>,
        linux-fsdevel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, miklos@...redi.hu,
        linux-kernel@...r.kernel.org, virtio-fs@...hat.com,
        dgilbert@...hat.com
Subject: Re: [PATCH 08/18] virtiofs: Drain all pending requests during
 ->remove time

On Fri, Sep 06, 2019 at 10:17:05AM -0400, Vivek Goyal wrote:
> On Fri, Sep 06, 2019 at 11:52:10AM +0100, Stefan Hajnoczi wrote:
> > On Thu, Sep 05, 2019 at 03:48:49PM -0400, Vivek Goyal wrote:
> > > +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
> > > +{
> > > +	WARN_ON(fsvq->in_flight < 0);
> > > +
> > > +	/* Wait for in flight requests to finish.*/
> > > +	while (1) {
> > > +		spin_lock(&fsvq->lock);
> > > +		if (!fsvq->in_flight) {
> > > +			spin_unlock(&fsvq->lock);
> > > +			break;
> > > +		}
> > > +		spin_unlock(&fsvq->lock);
> > > +		usleep_range(1000, 2000);
> > > +	}
> > 
> > I think all contexts that call this allow sleeping so we could avoid
> > usleep here.
> 
> usleep_range() is supposed to be used from non-atomic context.
> 
> https://github.com/torvalds/linux/blob/master/Documentation/timers/timers-howto.rst
> 
> What construct you are thinking of?
> 
> Vivek

completion + signal on vq callback?

-- 
MST