On Wed, Jan 09, 2013 at 10:06:16AM +0900, Alexandre Courbot wrote: > On Tue, Jan 8, 2013 at 9:59 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > > Please avoid the use of IS_ERR_OR_NULL(), especially on interfaces you > > introduce yourself. AFAICT, gpiod_get cannot return NULL, so you > > should not check for that. > > Sure - you sound like IS_ERR_OR_NULL() is generally considered evil, > may I ask why this is the case? I think I've explained that in the past; many people just do not think. They just use whatever macro they feel like is the right one. We keep seeing this, and this is a persistent problem. It's getting to be more of a problem because people are starting to argue back when you point out that they're wrong. People are even starting to believe that documentation which specifies explicitly "values where IS_ERR() is true are considered errors, everything else is valid" means that the use of IS_ERR_OR_NULL() in such cases is permissible. (I've had such an argument with two people recently.) So, interfaces which have well defined return values and even interfaces which specify _how_ errors should be checked end up being checked with the wrong macros. People constantly translate IS_ERR() to IS_ERR_OR_NULL() even when it's inappropriate. People don't think and people don't read documentation. People don't remember this level of detail. Whatever the excuse, the problem remains. IS_ERR_OR_NULL() always gets used inappropriately and without any regard to whether it's correct or not. So yes, IS_ERR_OR_NULL() _is_ pure evil. IMHO this macro is doing more harm than good. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
