From: Rusty Russell <rusty@rustcorp.com.au>
To: Tejun Heo <htejun@gmail.com>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>,
Jens Axboe <jens.axboe@oracle.com>,
linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-ide@vger.kernel.org
Subject: Re: [PATCH 0/7] sg_ring: a ring of scatterlist arrays
Date: Mon, 7 Jan 2008 19:34:01 +1100 [thread overview]
Message-ID: <200801071934.01597.rusty@rustcorp.com.au> (raw)
In-Reply-To: <4781C8B5.6050207@gmail.com>
On Monday 07 January 2008 17:37:41 Tejun Heo wrote:
> Rusty Russell wrote:
> > Hi Tejun,
> >
> > Nice try! Even ignoring the ugliness of undoing such an operation if
> > the caller doesn't expect you to mangle their chains, consider a
> > one-element sg array. :(
>
> Heh heh, that can be dealt with by skipping the first chain if the first
> chain is empty after chaining. Please take a look at
> ata_sg_setup_extra() in the following.
>
> http://git.kernel.org/?p=linux/kernel/git/tj/libata-dev.git;a=blob;f=driver
>s/ata/libata-core.c;h=32dde5bbc75ed53e89ac17040da2cd0621a37161;hb=c8847e473a
>4a2844244784226eb362be10d52ce9
>
> That said, yeah, it's seriously ugly. Restoring the original sg is ugly
> too. I definitely agree that we need some improvements here.
Erk, that's beyond ugly, into actual evil.
To make this general you need to find the last N 1-element chains (but SCSI
doesn't do this of course). Oh the horror...
I'd be remiss if I didn't mention that the sg_ring ata patches were
straightforward, and indescribably beautiful if compared to this!
Thanks,
Rusty.
next prev parent reply other threads:[~2008-01-07 8:34 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-19 6:31 [PATCH 0/7] sg_ring: a ring of scatterlist arrays Rusty Russell
2007-12-19 6:33 ` [PATCH 1/7] sg_ring: introduce " Rusty Russell
2007-12-19 7:31 ` [PATCH 2/7] sg_ring: use in virtio Rusty Russell
2007-12-19 7:33 ` [PATCH 3/7] sg_ring: blk_rq_map_sg_ring as a counterpart to blk_rq_map_sg Rusty Russell
2007-12-19 7:34 ` [PATCH 4/7] sg_ring: dma_map_sg_ring() helper Rusty Russell
2007-12-19 7:36 ` [PATCH 5/7] sg_ring: Convert core scsi code to sg_ring Rusty Russell
2007-12-19 7:37 ` [PATCH 6/7] sg_ring: libata simplification Rusty Russell
2007-12-19 7:38 ` [PATCH 7/7] sg_ring: convert core ATA code to sg_ring Rusty Russell
2007-12-26 8:36 ` Tejun Heo
2007-12-26 17:12 ` James Bottomley
2007-12-27 0:24 ` Rusty Russell
2007-12-27 4:21 ` Tejun Heo
2008-01-05 15:31 ` [PATCH 0/7] sg_ring: a ring of scatterlist arrays James Bottomley
2008-01-07 4:38 ` Rusty Russell
2008-01-07 5:01 ` Tejun Heo
2008-01-07 5:28 ` Rusty Russell
2008-01-07 6:37 ` Tejun Heo
2008-01-07 8:34 ` Rusty Russell [this message]
2008-01-07 8:45 ` Tejun Heo
2008-01-07 12:17 ` Herbert Xu
2008-01-07 15:48 ` James Bottomley
2008-01-08 0:39 ` Rusty Russell
2008-01-09 22:10 ` James Bottomley
2008-01-10 2:01 ` Rusty Russell
2008-01-10 15:27 ` James Bottomley
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