Re: [PATCH v4 4/5] drm: Add decoding of i915 ioctls

["Dmitry V. Levin" <ldv@xxxxxxxxxxxx>]

On Tue, Sep 08, 2015 at 04:18:11AM +0300, Dmitry V. Levin wrote:
[...]
> So the whole function should look smth like this:
> 
> static int i915_getparam(struct tcb *tcp, const unsigned int code, long arg)
> {
> 	struct drm_i915_getparam param;
> 
> 	if (entering(tcp)) {
> 		if (umove_or_printaddr(tcp, arg, &param))
> 			return RVAL_DECODED | 1;
> 		tprints(", {param=");

or rather
		tprints(", ");
		if (umove_or_printaddr(tcp, arg, &param))
			return RVAL_DECODED | 1;
		tprints("{param=");


> In this and other functions I slightly prefer
> 	if (umove_or_printaddr(tcp, arg, &param))
> 		return RVAL_DECODED | 1;
> over your variant because umove_or_printaddr() handles NULL address
> and !verbose(tcp) case better.

And the whole function will look as simple as this:

static int i915_setparam(struct tcb *tcp, const unsigned int code, long arg)
{
 	struct drm_i915_setparam param;

	tprints(", ");
	if (!umove_or_printaddr(tcp, arg, &param)) {
		tprints("{param=");
		printxval(drm_i915_setparams, param.param, "I915_PARAM_???");
		tprintf(", value=%d}", param.value);
	}

	return RVAL_DECODED | 1;
}

Note the absence of entering(tcp) check because this DRM_IOW parser always
returns a value with RVAL_DECODED flag set.


-- 
ldv

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