On Mon, 27 Aug 2007, vignesh babu wrote:
> On 8/26/07, Robert P. J. Day <rpjday@xxxxxxxxxxxxxx> wrote:
> > On Sun, 26 Aug 2007, vignesh babu wrote:
> >
> > just FYI, i ran my detection script on the entire tree and came up
> > with these possibilities for power of 2 cleanup -- i'm assuming
> > you've probably seen and processed some of them. as for the rest
> > of them, have fun. :-)
> wow...thanks for the list...i would cleanup as many of those...will
> mail u a list of committed changes to the list and will update wiki
> with the same sometime in the next few hours...
by the way, in some places, there is just some really weird sh*t going
on. like here, in fs/hfs/mdb.c:
/* size must be a multiple of 512 */
while (size & (size - 1))
size -= HFS_SECTOR_SIZE;
now, it turns out that HFS_SECTOR_SIZE is defined as 512, but i'm
baffled as to how continually *subtracting* 512 is going to end up
giving you a *multiple* of 512.
in general, i would be intensely suspicious of any loop that iterates
*until* something is a power of 2 -- that's probably something that
can be simplified. some of those cases are screamingly obvious, like
this from drivers/md/dm-snap.c:
/*
* Rounds a number down to a power of 2.
*/
static uint32_t round_down(uint32_t n)
{
while (n & (n - 1))
n &= (n - 1);
return n;
}
anyway, you get the idea.
rday
--
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA
http://crashcourse.ca
========================================================================
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