On 01/06/17 09:02, Borislav Petkov wrote: > On Thu, Jan 05, 2017 at 11:52:07PM +0000, Junichi Nomura wrote: >>>> + p = kzalloc(sizeof(struct ucode_patch), GFP_KERNEL); >>> >>> Perhaps sizeof(*p) ? >> >> Yeah, that might be preferred. > > No, those things are never preferred because > > sizeof(struct <type>) > > tells you exactly the size of what kind of object you're getting vs > > sizeof(*p) > > which tells you you're getting the size of what p points to. > > Now you have to go look at p and what type it is. In the current case, p > is defined not far away from the use site but in a larger function, you > most likely need to eyeball up to its type when reading the code. Which > makes the whole thing less readable.
Personally I have same opinion as yours. :) But according to Documentation/process/coding-style.rst, it seems "sizeof(*p)" is preferred style and the reason there makes some sense. Quote from coding-style.rst: > The preferred form for passing a size of a struct is the following: > > p = kmalloc(sizeof(*p), ...); > > The alternative form where struct name is spelled out hurts readability and > introduces an opportunity for a bug when the pointer variable type is changed > but the corresponding sizeof that is passed to a memory allocator is not. I'm fine with either way. -- Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd.
