linux-kernel - Re: [PATCH v4 5/5] drm/qxl: properly free qxl releases

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:   Wed, 3 Feb 2021 14:04:15 +0100
From:   Gerd Hoffmann <kraxel@...hat.com>
To:     dri-devel@...ts.freedesktop.org, Dave Airlie <airlied@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <virtualization@...ts.linux-foundation.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <spice-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 5/5] drm/qxl: properly free qxl releases

> > +	/*
> > +	 * Ask host to release resources (+fill release ring),
> > +	 * then wait for the release actually happening.
> > +	 */
> > +	qxl_io_notify_oom(qdev);
> > +	for (try = 0; try < 20 && atomic_read(&qdev->release_count) > 0; try++)
> > +		msleep(20);
> 
> A bit icky, why not use a wait queue or something like that instead of
> hand-rolling this? Not for perf reasons, just so it's a bit clear who
> waits for whom and why.

There isn't one ready for use, and adding a new one (to wait for the
garbage collection having released something) just for a clean shutdown
looked a bit like overkill.

But after digging a bit more and looking at the qxl_fence_wait() mess I
think adding a wait queue looks like a good idea ...

v5 coming soon ...

take care,
  Gerd