linux-kernel - Re: [net-next PATCH RFC 19/26] arch/sparc: Add option to skip DMA sync as a part of map and unmap

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: <20161024.142730.1316656811538193943.davem@davemloft.net>
Date:   Mon, 24 Oct 2016 14:27:30 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     alexander.h.duyck@...el.com
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, sparclinux@...r.kernel.org, brouer@...hat.com
Subject: Re: [net-next PATCH RFC 19/26] arch/sparc: Add option to skip DMA
 sync as a part of map and unmap

From: Alexander Duyck <alexander.h.duyck@...el.com>
Date: Mon, 24 Oct 2016 08:06:07 -0400

> This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
> avoid invoking cache line invalidation if the driver will just handle it
> via a sync_for_cpu or sync_for_device call.
> 
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: sparclinux@...r.kernel.org
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>

This is fine for avoiding the flush for performance reasons, but the
chip isn't going to write anything back unless the device wrote into
the area.