From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH v2 1/3] software node: implement reference properties Date: Sat, 7 Sep 2019 20:12:51 +0300 Message-ID: <20190907171251.GL2680@smile.fi.intel.com> References: <20190906222611.223532-1-dmitry.torokhov@gmail.com> <20190907160819.GH2680@smile.fi.intel.com> <20190907163240.GA27112@dtor-ws> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190907163240.GA27112@dtor-ws> Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Torokhov Cc: "Rafael J. Wysocki" , Heikki Krogerus , Linus Walleij , linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org List-Id: platform-driver-x86.vger.kernel.org On Sat, Sep 07, 2019 at 09:32:40AM -0700, Dmitry Torokhov wrote: > On Sat, Sep 07, 2019 at 07:08:19PM +0300, Andy Shevchenko wrote: > > On Fri, Sep 06, 2019 at 03:26:09PM -0700, Dmitry Torokhov wrote: > > > + } else if (src->type == DEV_PROP_REF) { > > > + /* All reference properties must be arrays */ > > > + return -EINVAL; > > > > Hmm... What about to duplicate pointer under value union and use is_array to > > distinguish which one to use? Because... > > Then we have to special-case copying this entry, similar to the pains we > are going with the strings. I can't see it as a pain. Simple do the same kmemdup() for the case when is_array = false and DEV_TYPE_REF? By the way, don't we need to update property_entry_{get,set}_pointer()? > > > + .is_array = true, \ > > > > I really don't like this "cheating". > > This is not cheating. Any single value can be represented as an array of > one element. Actually, the only reason we have this "is_array" business > is because for scalar values and short strings it is much cheaper to > store single value in-line instead of out of line + pointer, especially > on 64 bit arches. Yes, and this is a lot of benefit! > If you want we can change is_array into is_inline. Nope, is_array is exactly what it tells us about the content. Its functional load is to distinguish which union (value vs. pointer) we are using. -- With Best Regards, Andy Shevchenko