From: Valdis.Kletnieks@vt.edu
To: Steven Whitehouse <swhiteho@redhat.com>
Cc: linux-kernel@vger.kernel.org, cluster-devel@redhat.com
Subject: Re: [PATCH 1/3] bitops: Add __ffs64 bitop
Date: Mon, 27 Apr 2009 09:40:35 -0400 [thread overview]
Message-ID: <52615.1240839635@turing-police.cc.vt.edu> (raw)
In-Reply-To: Your message of "Thu, 23 Apr 2009 10:16:54 BST." <1240478216-2594-2-git-send-email-swhiteho@redhat.com>
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On Thu, 23 Apr 2009 10:16:54 BST, Steven Whitehouse said:
> Finds the first set bit in a 64 bit word. This is required in order
> to fix a bug in GFS2, but I think it should be a generic function
> in case of future users.
Seems like a sane idea..
> +static inline unsigned long __ffs64(u64 word)
> +{
> +#if BITS_PER_LONG == 32
> + if (((u32)word) == 0UL)
> + return __ffs((u32)(word >> 32)) + 32;
> +#elif BITS_PER_LONG != 64
> +#error BITS_PER_LONG not 32 or 64
> +#endif
> + return __ffs((unsigned long)word);
> +}
> +
Does this have endian-ness issues (is that (u32)word the "high" or "low"
part)? Or is this intended only for looking at bitmaps and the like, and we
don't really care?
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next prev parent reply other threads:[~2009-04-27 15:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-23 9:16 GFS2: Block alloc fixes Steven Whitehouse
2009-04-23 9:16 ` [PATCH 1/3] bitops: Add __ffs64 bitop Steven Whitehouse
2009-04-23 9:16 ` [PATCH 2/3] GFS2: Fix bug in block allocation Steven Whitehouse
2009-04-23 9:16 ` [PATCH 3/3] GFS2: Ensure that the inode goal block settings are updated Steven Whitehouse
2009-04-27 13:40 ` Valdis.Kletnieks [this message]
2009-04-27 15:41 ` [PATCH 1/3] bitops: Add __ffs64 bitop Steven Whitehouse
2009-04-27 16:31 ` Valdis.Kletnieks
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