[lkml]   [2012]   [Mar]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: Regression introduced by bfcfaa77bdf0f775263e906015982a608df01c76 (vfs: use 'unsigned long' accesses for dcache name comparison and hashing)
    On Thu, Mar 22, 2012 at 01:38:28PM -0700, Linus Torvalds wrote:
    > On Thu, Mar 22, 2012 at 1:24 PM, Al Viro <> 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.

    See upthread for diff doing just that ;-) Let's see if that fixes the
    crap guys are seeing... BTW, you have used full_name_hash(), just not
    on something 8 char long - devpts uses d_alloc_name(), but pty numbers
    tend to be less than ten millions...

     \ /
      Last update: 2012-03-22 21:47    [W:0.019 / U:27.752 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site