netdev - Re: [PATCH 3/3] virtio_ring: unify direct/indirect code paths.

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: <CALCETrVCR+Zm9RtF7gGmO-XcMAb4fLsxKMG-aEABqhbywF9+Jw@mail.gmail.com>
Date:	Wed, 3 Sep 2014 18:59:33 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	netdev <netdev@...r.kernel.org>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Linux Virtualization <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH 3/3] virtio_ring: unify direct/indirect code paths.

On Tue, Sep 2, 2014 at 9:29 PM, Rusty Russell <rusty@...tcorp.com.au> wrote:
> virtqueue_add() populates the virtqueue descriptor table from the sgs
> given.  If it uses an indirect descriptor table, then it puts a single
> descriptor in the descriptor table pointing to the kmalloc'ed indirect
> table where the sg is populated.
>
> Previously vring_add_indirect() did the allocation and the simple
> linear layout.  We replace that with alloc_indirect() which allocates
> the indirect table then chains it like the normal descriptor table so
> we can reuse the core logic.
>

> +       if (vq->indirect && total_sg > 1 && vq->vq.num_free)
> +               desc = alloc_indirect(total_sg, gfp);
> +       else
> +               desc = NULL;
> +
> +       if (desc) {
> +               /* Use a single buffer which doesn't continue */
> +               vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT;
> +               vq->vring.desc[head].addr = virt_to_phys(desc);
> +               /* avoid kmemleak false positive (hidden by virt_to_phys) */
> +               kmemleak_ignore(desc);
> +               vq->vring.desc[head].len = total_sg * sizeof(struct vring_desc);
> +
> +               /* Set up rest to use this indirect table. */
> +               i = 0;
> +               total_sg = 1;

This is a little too magical for me.  Would it make sense to add a new
variable for this (total_root_descs or something)?

--Andy
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html