* sg_is_chain() call in coh901318_lli_fill_sg()
@ 2013-02-04 11:33 Bart Van Assche
2013-02-19 12:05 ` Per Forlin
0 siblings, 1 reply; 2+ messages in thread
From: Bart Van Assche @ 2013-02-04 11:33 UTC (permalink / raw)
To: linux-arm-kernel
Hello,
I'm trying to understand how coh901318_lli_fill_sg() works by studying
the source code of that function. In that function I found the following
code:
for_each_sg(sgl, sg, nents, i) {
if (sg_is_chain(sg)) {
[ ... ]
Can anyone explain me why that construct makes sense ? As far as I can
see in lib/scatterlist.c sg_next() ensures that the for_each_sg() skips
those elements for which sg_is_chain(sg) == true. Does that mean that
sg_is_chain(sg) always evaluates to false in the above loop ?
Thanks,
Bart.
^ permalink raw reply [flat|nested] 2+ messages in thread* sg_is_chain() call in coh901318_lli_fill_sg()
2013-02-04 11:33 sg_is_chain() call in coh901318_lli_fill_sg() Bart Van Assche
@ 2013-02-19 12:05 ` Per Forlin
0 siblings, 0 replies; 2+ messages in thread
From: Per Forlin @ 2013-02-19 12:05 UTC (permalink / raw)
To: linux-arm-kernel
Hi Bart,
On Mon, Feb 4, 2013 at 12:33 PM, Bart Van Assche <bvanassche@acm.org> wrote:
> Hello,
>
> I'm trying to understand how coh901318_lli_fill_sg() works by studying the
> source code of that function. In that function I found the following code:
>
> for_each_sg(sgl, sg, nents, i) {
> if (sg_is_chain(sg)) {
> [ ... ]
>
> Can anyone explain me why that construct makes sense ?
I think the answer is: it doesn't make sense.
> As far as I can see
> in lib/scatterlist.c sg_next() ensures that the for_each_sg() skips those
> elements for which sg_is_chain(sg) == true. Does that mean that
> sg_is_chain(sg) always evaluates to false in the above loop ?
Yes, I agree. I'm guilt of adding this check a long time ago due to sg
misconceptions. Today I no longer recall what the misconception was.
Linus, you may remove this check.
Thanks for spotting this,
Per
^ permalink raw reply [flat|nested] 2+ messages in thread
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2013-02-04 11:33 sg_is_chain() call in coh901318_lli_fill_sg() Bart Van Assche
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