linux-kernel - Re: [Patch] SCSI: Retrieve Cache Mode Using SG_ATA

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: <4E941D5E.6060101@suse.de>
Date:	Tue, 11 Oct 2011 12:41:34 +0200
From:	Hannes Reinecke <hare@...e.de>
To:	Amit Sahrawat <amit.sahrawat83@...il.com>
Cc:	James Bottomley <James.Bottomley@...senpartnership.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Douglas Gilbert <dgilbert@...erlog.com>,
	linux-usb@...r.kernel.org, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Christoph Hellwig <hch@...radead.org>,
	NamJae Jeon <linkinjeon@...il.com>
Subject: Re: [Patch] SCSI: Retrieve Cache Mode Using SG_ATA_16 if normal routine
 fails

On 10/11/2011 10:26 AM, Amit Sahrawat wrote:
> SCSI: Retrieve Cache Mode Using SG_ATA_16 if normal routine fails
>
> It has been observed that a number of USB HDD's do not respond correctly
> to SCSI mode sense command(retrieve caching pages) which results in their
> Write Cache being discarded by queue requests i.e., WCE if left set to
> '0'(disabled). So, in order to identify the devices correctly - give it
> a last try using SG_ATA_16 after failure from normal routine.
>
I'd be _VERY_ cautious when trying something like this.

ATA_16 is a rather recent command, and most older drives simply 
can't cope with this. Instead they just kick the error handler and 
go offline eventually.

Shouldn't we rather use a sensible default, ie assume WCE is enabled?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@...e.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
--
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/