[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <4A5CB3A3.6000407@vlnb.net>
Date: Tue, 14 Jul 2009 20:34:43 +0400
From: Vladislav Bolkhovitin <vst@...b.net>
To: Jens Axboe <jens.axboe@...cle.com>
CC: linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
scst-devel@...ts.sourceforge.net, Tejun Heo <tj@...nel.org>,
Boaz Harrosh <bharrosh@...asas.com>,
James Bottomley <James.Bottomley@...senPartnership.com>,
FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Subject: Re: [PATCH]: Rename REQ_COPY_USER to more descriptive REQ_HAS_TAIL_SPACE_FOR_PADDING
Vladislav Bolkhovitin, on 07/09/2009 10:30 PM wrote:
> Jens Axboe, on 07/09/2009 10:17 PM wrote:
>> On Thu, Jul 09 2009, Vladislav Bolkhovitin wrote:
>>> Currently names of REQ_COPY_USER and __REQ_COPY_USER constants are confusing,
>>> because they actually mean that the buffer for the corresponding requests
>>> has space in the tail for padding in case of DMA padding restrictions.
>> No, that's not what it means, the fact that there's padding room is a
>> side effect of the map type. So I'd suggest adding a comment above that
>> if {} in blk_rq_map_sg(), something that should have been there from the
>> beginning.
>
> Can you elaborate a bit more about what REQ_COPY_USER should mean, please?
>
> As far as I can see from the sources, currently it's used to only to
> determine if there is the padding space. Maybe, the original meaning
> doesn't make sense anymore?
Jens,
Sorry for bothering you, but with use of the kernel-generated buffers,
like in the patch I sent in
http://groups.google.com/group/linux.kernel/browse_thread/thread/b5127eeadbef934e/5da7ec7b424d2f36?lnk=raot
name REQ_COPY_USER becomes quite misleading.
For instance, for blk_rq_map_kern_sg() usage of REQ_COPY_USER the
buffers neither copied, nor from user. Plus, as I wrote above, in 2.6.30
REQ_COPY_USER used only to determine if there is the padding space in
the end. Hence, I suggested the rename.
Thanks,
Vlad
--
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/
Powered by blists - more mailing lists