Messages in this thread | | | From | Linus Torvalds <> | Date | Thu, 22 Mar 2012 13:38:28 -0700 | Subject | Re: Regression introduced by bfcfaa77bdf0f775263e906015982a608df01c76 (vfs: use 'unsigned long' accesses for dcache name comparison and hashing) |
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On Thu, Mar 22, 2012 at 1:24 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: > > OK, full_name_hash()/hash_name() definitely have a mismatch and it's on the > names of length 8*n: trivial experiment shows that we have > name hash_name full_name_hash
Good catch, guys.
Ugh. And I never noticed despite having run this code on my machines for several weeks, because I don't think I have anything that uses the "full_name_hash()" function. And it looked so obviously the same.
> Linus, which way do you prefer to shift it? Should hash_name() change to > match full_name_hash() or should it be the other way round? > > What happens is that you get multiplication by 9 and adding 0 in the former, > after having added the last full word. In the latter we add the last full > word, see that there's nothing left and bugger off.
Yes. I think we should make things match "hash_name()", because that's the one that is critical and we want to really generate good code for.
I think you can just move the "*=9" down in full_name_hash(), so that we always "pre-multiply" the hash for the next round. But I'll have to double-check my logic.
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