linux-kernel - Re: [PATCH 0/9] virtio: new API for addition of buffers, scatterlist changes

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]

Date:	Fri, 15 Feb 2013 19:04:19 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	unlisted-recipients:; (no To-header on input)
CC:	Rusty Russell <rusty@...tcorp.com.au>, kvm@...r.kernel.org,
	mst@...hat.com, linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH 0/9] virtio: new API for addition of buffers, scatterlist
 changes

Il 14/02/2013 10:23, Paolo Bonzini ha scritto:
>> > How about this as a first step?
>> > 
>> > virtio_ring: virtqueue_add_sgs, to add multiple sgs.
>> > 
>> > virtio_scsi and virtio_blk can really use these, to avoid their current
>> > hack of copying the whole sg array.
>> > 
>> > Signed-off-by: Ruty Russell <rusty@...tcorp.com.au> 
> It's much better than the other prototype you had posted, but I still
> dislike this...  You pay for additional counting of scatterlists when
> the caller knows the number of buffers; and the nested loops aren't
> free, either.

Another problem is that you cannot pass "truncated" scatterlists.  You
must ensure there is an end marker on the last item.  I'm not sure if
the kernel ensures that, given that for_each_sg takes explicitly the
number of scatterlist elements; and it is not as trivial as
"sg_mark_end(foo + nsg - 1);" if the upper layers hand you a chained
scatterlist.

Paolo
--
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/