Re: [PATCH] lockd: fix arg parsing for grace_period and timeout.

[NeilBrown <neilb@suse.de>]

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On Tue, 7 Feb 2012 09:49:56 -0500 "J.Bruce Fields" <bfields@fieldses.org>
wrote:

> On Tue, Feb 07, 2012 at 01:58:43PM +0000, Myklebust, Trond wrote:
> > On Tue, 2012-02-07 at 15:35 +1100, NeilBrown wrote:
> > > If you try to set grace_period or timeout via a module parameter
> > > to lockd, and do this on a big-endian machine where
> > > 
> > >    sizeof(int) != sizeof(unsigned long)
> > > 
> > > it won't work.  This number given will be effectively shifted right
> > > by the difference in those two sizes.
> > > 
> > > So cast kp->arg properly to get correct result.
> > > 
> > > Signed-off-by: NeilBrown <neilb@suse.de>
> > > 
> > > diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
> > > index c061b9a..2444780 100644
> > > --- a/fs/lockd/svc.c
> > > +++ b/fs/lockd/svc.c
> > > @@ -440,7 +440,7 @@ static int param_set_##name(const char *val, struct kernel_param *kp)	\
> > >  	__typeof__(type) num = which_strtol(val, &endp, 0);		\
> > >  	if (endp == val || *endp || num < (min) || num > (max))		\
> > >  		return -EINVAL;						\
> > > -	*((int *) kp->arg) = num;					\
> > > +	*((type *) kp->arg) = num;					\
> > >  	return 0;							\
> > >  }
> > >  
> > Wow, that's a seriously old bug...
> 
> Looking at a historical git repo, it was probably from "[PATCH] make NFS
> lockd port numbers assignable at run time", attributed to Jamie Lokier
> in August 2003, in 2.6.0.
> 
> Anyway:
> 
> > Bruce, do you want to carry it?
> 
> Sure.  I'm a little slow getting stuff pushed out while I track down a
> couple very tricky bugs, but it should show up in my git tree in a few
> days....

Thanks.. just goes to show how well big-endian is tested I guess :-)
especially the more obscure options.

NeilBrown

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