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Date:   Fri, 6 Sep 2019 10:17:05 -0400
From:   Vivek Goyal <vgoyal@redhat.com>
To:     Stefan Hajnoczi <stefanha@redhat.com>
Cc:     linux-fsdevel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, miklos@szeredi.hu,
        linux-kernel@vger.kernel.org, virtio-fs@redhat.com,
        dgilbert@redhat.com, mst@redhat.com
Subject: Re: [PATCH 08/18] virtiofs: Drain all pending requests during
 ->remove time
Message-ID: <20190906141705.GF22083@redhat.com>
References: <20190905194859.16219-1-vgoyal@redhat.com>
 <20190905194859.16219-9-vgoyal@redhat.com>
 <20190906105210.GP5900@stefanha-x1.localdomain>
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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