2012/6/14 Takuya Yoshikawa [off-list ref]:

On Wed, 13 Jun 2012 08:21:18 -0700
Grant Grundler [off-list ref] wrote:

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Should this hash_table be converted from u16 hash_table[32] to
DECLARE_BITMAP(hash_table, 16 * 32) to ensure that it is aligned
on long-word boundary?

I think hash_table is already long-word aligned because it is placed
right after a pointer.

I recommend converting to proper bitmap.  Because such an implicit
assumption is easily broken by someone touching this function.

Do you mean something like:
       DECLARE_BITMAP(__hash_table, 16 * 32);
       u16 *hash_table = (u16 *)__hash_table;
?

Grant, what do you think about this?

Hi Takuya,
two thoughts:
1) while I agree with Akinobu and thank him for pointing out a
_potential_ alignment problem, this is a separate issue and your
existing patch should go in anyway. There are probably other drivers
with _potential_ alignment issues. Akinobu could get credit for
finding them by submitting patches after reviewing calls to set_bit
and set_bit_le() - similar to what you are doing now.

I prefer approach 1.

hash_table is local in build_setup_frame_hash(), so if further
improvement is also required, we can do that locally there later.

This potential alignment problem is introduced by this patch.  Because
the original set_bit_le() in tulip driver can handle unaligned bitmap.
This is why I recommended it should be fixed in this patch.

But please just ignore me if I'm too much paranoid.  And I'll handle
this issue if no one wants to do it.