On Tue 11-12-18 10:19:05, Wei Yang wrote: > On Tue, Dec 11, 2018 at 10:44:41AM +0100, Michal Hocko wrote: > >On Tue 11-12-18 11:51:28, Wei Yang wrote: > >> A valid present section number is in [0, __highest_present_section_nr]. > >> And the return value of next_present_section_nr() meets this > >> requirement. This means it is not necessary to check it with > >> __highest_present_section_nr again in for_each_present_section_nr(). > >> > >> Since we pass an unsigned long *section_nr* to > >> for_each_present_section_nr(), we need to cast it to int before > >> comparing. > > > >Why do we want this patch? Is it an improvement? If yes, it is > >performance visible change or does it make the code easier to maintain? > > > > Michal > > I know you concern, maintainance is a very critical part of review. > > >To me at least the later seems dubious to be honest because it adds a > >non-obvious dependency of the terminal condition to the > >next_present_section_nr implementation and that might turn out error > >prone. > > > > While I think the original code is not that clear about the syntax. > > When we look at the next_present_section_nr(section_nr), the return > value falls into two categories: > > -1 : no more present section after section_nr > other: the next present section number after section_nr > > Based on this syntax, the iteration could be simpler to terminate > when the return value is less than 0. This is what the patch tries to > do. > > Maybe I could do more to help the maintainance: > > * add some comment about the return value of next_present_section_nr > * terminate the loop when section_nr == -1 > > Hope this would help a little. Well, not really. Nothing of the above seems to matter to callers of the code. So I do not see this as a general improvement and as such no strong reason to merge it. It is basicly polishing a code without any obvious issues. -- Michal Hocko SUSE Labs
