linux-kernel - Re: [PATCH 4/4] nvmet-fc: Use new SGL alloc/free helper for requests

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:   Thu, 29 Mar 2018 20:15:45 +0200
From:   Christoph Hellwig <hch@....de>
To:     Logan Gunthorpe <logang@...tatee.com>
Cc:     James Smart <james.smart@...adcom.com>,
        linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>
Subject: Re: [PATCH 4/4] nvmet-fc: Use new SGL alloc/free helper for
        requests

On Thu, Mar 29, 2018 at 11:02:10AM -0600, Logan Gunthorpe wrote:
> Per the bug in the previous patch, I don't think that was ever a valid
> assumption. It doesn't have anything to do with the sgl_alloc change
> either. The dma_map interface is allowed to merge SGLs and that's why it
> can return fewer nents than it was passed. I'm not sure how many or
> which DMA ops actually do this which is why it hasn't actually
> manifested itself as a bug; but it is part of how the interface is
> specified to work.

Most iommus can, it just is very unlikely do happen in block drivers
given that the block layer already merges segments higher up.