linux-kernel - Re: [PATCH] scatterlist: define SG chain for arm architecture

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, 2 Dec 2010 11:41:39 -0600
From:	"Guzman Lugo, Fernando" <fernando.lugo@...com>
To:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Cc:	linux@....linux.org.uk, linux-arm-kernel@...ts.infradead.org,
	Hiroshi.DOYU@...ia.com,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Omar Ramirez Luna <omar.ramirez@...com>,
	Bhavin Shah <bshah@...com>, Vijay Pasam <vpasam@...com>
Subject: Re: [PATCH] scatterlist: define SG chain for arm architecture

On Sun, Oct 3, 2010 at 6:34 AM, FUJITA Tomonori
<fujita.tomonori@....ntt.co.jp> wrote:
> On Sun, 3 Oct 2010 12:28:39 +0100
> Russell King - ARM Linux <linux@....linux.org.uk> wrote:
>
>> On Sun, Oct 03, 2010 at 08:02:52PM +0900, FUJITA Tomonori wrote:
>> > On Fri, 1 Oct 2010 17:39:58 +0100
>> > Russell King - ARM Linux <linux@....linux.org.uk> wrote:
>> >
>> > > On Fri, Oct 01, 2010 at 11:28:41AM -0500, Fernando Guzman Lugo
> wrote:
>> > > > Define SG chain for ARM architecture in order to work
>> > > > with big buffers. This patch is needed in order to
>> > > > iovmm users can pass a big buffer to map it and ARM
>> > > > architecture has not issues using SG chain.
>> > > >
>> > > > This change was suggested by FUJITA Tomonori.
>> > >
>> > > Have you audited all places where SG lists are used in the ARM
>> > > architecture to ensure that SG chain support is safe?  (That
>> > > goes for ARM generic code and ARM specific drivers.)
>> >
>> > As far as I know, only SCSI actually uses SG chain feature (that is,
>> > sending chained scatter lists). All SCSI drivers were converted when
>> > we added SG chain feature. So what you need to care about is the dma
>> > code.
>> >
>> > There are only several files that actually use scatter list under
>> > arch/arm.
>> >
>> > >From a quick look, arch/arm/mm/dma-mapping.c,
>> > arch/arm/common/dmabounce.c, arch/arm/kernel/dma.c, and
>> > arch/arm/include/asm/dma-mapping.h looks fine.
>> >
>> > arm/mach-imx/dma-v1.c also looks like to use chained sg API properly
>> > (but this isn't used with SCSI, right?).
>> >
>> > Seems that arch/arm/plat-omap/iovmm.c can handle the chained SG
>> > too. It doesn't allocate the chained SG now though.
>>
>> There's also RiscPC and its SCSI drivers could well be an issue for SG
>> chaining.  They have to manually save the SCSI 'data pointer' (down to
>> the byte position in the SG chain and be able to restore a previously
>> saved point.)  This code was written before SG chaining ever appeared,
>> and although it has been partly fixed up, it's probably buggy if SG
>> chaining were to be enabled.
>
> What SCSI drviers we need to fix?

Russell,

Any update with this? I hope it can be merged for 2.6.38.

>
>
>> If it's just OMAP users who wish to enable SG chaining, then the sane
>> thing to do would be to make the definition of the macro conditional
>> on OMAP.
>
> Yeah, that should work.

some like this in scatterlist.h is ok?

#ifdef CONFIG_ARCH_OMAP
#define ARCH_HAS_SG_CHAIN
#endif


Regards,
Fernando.
>
--
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/