linux-kernel - Re: [PATCH 5 of 5] virtio: expose added descriptors immediately

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

Message-ID: <20111123083005.GD22734@redhat.com>
Date:	Wed, 23 Nov 2011 10:30:06 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	virtualization <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH 5 of 5] virtio: expose added descriptors immediately

On Wed, Nov 23, 2011 at 11:49:01AM +1030, Rusty Russell wrote:
> On Tue, 22 Nov 2011 08:29:08 +0200, "Michael S. Tsirkin" <mst@...hat.com> wrote:
> > On Tue, Nov 22, 2011 at 11:03:04AM +1030, Rusty Russell wrote:
> > > -	/* If you haven't kicked in this long, you're probably doing something
> > > -	 * wrong. */
> > > -	WARN_ON(vq->num_added > vq->vring.num);
> > > +	/* This is very unlikely, but theoretically possible.  Kick
> > > +	 * just in case. */
> > > +	if (unlikely(vq->num_added == 65535))
> > 
> > This is 0xffff but why use the decimal notation?
> 
> Interesting.  Why use hex?  Feels more like binary?

Just easier to see it's the largest 16 bit number.

> But I've changed it to "(1 << 16) - 1" to be clear.

That's even better.

> > > +		virtqueue_kick(_vq);
> > >  
> > >  	pr_debug("Added buffer head %i to %p\n", head, vq);
> > >  	END_USE(vq);
> > 
> > We also still need to reset vq->num_added, right?
> 
> virtqueue_kick does that for us.
> 
> Cheers,
> Rusty.

Right.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/