linux-kernel - Re: [PATCH] raid5: panic() on dma_wait_for_async

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: <84A937D219C2B44EB8EA44831ACA1E49166C741F@SC-MBX02-3.TheFacebook.com>
Date:	Mon, 19 Nov 2012 05:22:25 +0000
From:	Dan Williams <djbw@...com>
To:	NeilBrown <neilb@...e.de>
CC:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-raid@...r.kernel.org" <linux-raid@...r.kernel.org>,
	Vinod Koul <vinod.koul@...el.com>,
	Tomasz Figa <t.figa@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>
Subject: Re: [PATCH] raid5: panic() on dma_wait_for_async_tx() error

On 11/18/12 5:06 PM, "NeilBrown" <neilb@...e.de> wrote:

>
>Hi Dan,
> could you comment on this please?  Would it make sense to arrange for
>errors
> to propagate up?  Or should we arrange to do a software-fallback in the
>dma
> engine is a problem?  What sort of things can cause error here anyway?

Propagating up is missing reliable "dma abort" operation.

In these cases the engine failed to complete due to hardware hang / driver
bug, or has hit a memory error (uncorrectable even with software
fallback).  This originally should have been using async_tx_quiesce()
which also does the panic.

The engines that I have worked with have either lacked support for
aborting, or were otherwise unable to recover from a hardware hang.
However, for engines that do support error recovery they should be able to
hide the failure from the upper layers.

--
Dan

--
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/