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

[Dmitry V. Levin]

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.


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