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From: Michael Tokarev <mjt@tls.msk.ru>
To: Neil Brown <neilb@suse.de>
Cc: Paul Clements <paul.clements@steeleye.com>, linux-raid@vger.kernel.org
Subject: Re: [BUG/PATCH] md bitmap broken on big endian machines
Date: Fri, 29 Sep 2006 02:09:24 +0400	[thread overview]
Message-ID: <451C4814.9030601@tls.msk.ru> (raw)
In-Reply-To: <17691.27892.571457.628971@cse.unsw.edu.au>

Neil Brown wrote:
[]
> Use ffz instead of find_first_set to convert multiplier to shift.
> 
> From: Paul Clements <paul.clements@steeleye.com>
> 
> find_first_set doesn't find the least-significant bit on bigendian
> machines, so it is really wrong to use it.
> 
> ffs is closer, but takes an 'int' and we have a 'unsigned long'.
> So use ffz(~X) to convert a chunksize into a chunkshift.

So we don't use ffs(int) for an unsigned value because of int vs
unsigned int, but we use ffz() with negated UNSIGNED.  Looks even
more broken to me, even if it happens to work correctly... ;)

/mjt

  reply	other threads:[~2006-09-28 22:09 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-09-21 20:26 [BUG/PATCH] md bitmap broken on big endian machines Paul Clements
2006-09-22 15:29 ` [PATCH] md SET_BITMAP_FILE compat ioctl Paul Clements
2006-09-28  7:31   ` Neil Brown
2006-09-28  6:34 ` [BUG/PATCH] md bitmap broken on big endian machines Neil Brown
2006-09-28 22:09   ` Michael Tokarev [this message]
2006-09-29  0:48     ` Paul Clements
2006-09-29  7:03       ` Michael Tokarev

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