Re: NFS structure allocation alignment patch
David Woodhouse (dwmw2@infradead.org)
Thu, 10 Jul 2003 12:05:21 +0100
On Mon, 2003-06-30 at 14:52, Richard Curnow wrote:
> Hi Trond, Marcelo,
>
> Below is a patch against 2.4.21 to tidy up the allocation of two
> structures in nfs3_proc_unlink_setup. We need this change for NFS to
> work on the sh64 architecture, which has just been merged into 2.4 in
> the last couple of days. Otherwise, 'res' is 4-byte aligned but not
> necessarily 8-byte aligned, but struct nfs_attr contains fields that are
> 8 bytes wide. This leads to alignment exceptions on loads and stores
> into that structure.
What's wrong with alignment exceptions? They get fixed up by your
exception handler, surely?
If you assert that it's a performance-critical path and hence we
shouldn't be relying on the exception fixup, that's fine -- but in that
case it's not a correctness fix, it's just an optimisation.
--
dwmw2
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