Re: [PATCH v4 01/17] x86/mpx: Do not use SIB index if index points to R/ESP

[Joe Perches]

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.