2012/6/14 Takuya Yoshikawa <takuya.yoshikawa@xxxxxxxxx>: > On Wed, 13 Jun 2012 08:21:18 -0700 > Grant Grundler <grantgrundler@xxxxxxxxx> wrote: > >> >> >> 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. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
