Re: [PATCH v4 01/17] x86/mpx: Do not use SIB index if index points to R/ESP
From: Ricardo Neri
Date: Thu Feb 23 2017 - 21:42:52 EST
On Thu, 2017-02-23 at 18:33 -0800, Joe Perches wrote:
> On Thu, 2017-02-23 at 14:17 -0800, Ricardo Neri wrote:
> > On Thu, 2017-02-23 at 08:24 +0100, Peter Zijlstra wrote:
> > > On Wed, Feb 22, 2017 at 10:36:50PM -0800, Ricardo Neri wrote:
> > > > + /*
> > > > + * A negative offset generally means a error, except
> > > > + * -EDOM, which means that the contents of the register
> > > > + * should not be used as index.
> > > > + */
> > > > if (indx_offset < 0)
> > > > - goto out_err;
> > > > + if (indx_offset == -EDOM)
> > > > + indx = 0;
> > > > + else
> > > > + goto out_err;
> > > > + else
> > > > + indx = regs_get_register(regs, indx_offset);
> > >
> > > Kernel coding style requires more brackets than are strictly required by
> > > C, any block longer than 1 line needs then. Also, if one leg of a
> > > conditional needs them, then they should be on both legs.
> > >
> > > Your code has many such instances, please change them all.
> >
> > Will do. Sorry for the noise. These instances escaped the checkpatch
> > script.
>
> Also, this code would read better with the inner test
> reversed or done first
>
> if (indx_offset < 0) {
> if (indx_offset != -EDOM)
> goto out_err;
> indx = 0;
> } else {
> indx = regs_get_register(etc...)
> }
>
> or
> if (indx_offset == -EDOM)
> indx = 0;
> else if (indx_offset < 0)
> goto err;
> else
> indx = regs_get_register(etc...)
>
> The compiler should generate the same code in any
> case, but either could improve reader understanding.
I agree! I will change it with your clever solution.
Thanks and BR,
Ricardo