On Thu 2018-12-13 16:29:59, Josh Poimboeuf wrote: > On Thu, Dec 06, 2018 at 09:36:06AM -0500, Joe Lawrence wrote: > > On 12/06/2018 05:14 AM, Petr Mladek wrote: > > > On Thu 2018-12-06 10:23:40, Miroslav Benes wrote: > > >> On Thu, 6 Dec 2018, Petr Mladek wrote: > > >> > > >>> On Wed 2018-12-05 14:32:53, Joe Lawrence wrote: > > >>>>> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > > >>>>> index 972520144713..e01dfa3b58d2 100644 > > >>>>> --- a/kernel/livepatch/core.c > > >>>>> +++ b/kernel/livepatch/core.c > > >>>>> @@ -45,7 +45,7 @@ > > >>>>> */ > > >>>>> DEFINE_MUTEX(klp_mutex); > > >>>>> > > >>>>> -/* Registered patches */ > > >>>>> +/* Actively used patches. */ > > >>>>> LIST_HEAD(klp_patches); > > >>>> > > >>>> By itself, this comment makes me wonder if there are un-active and/or > > >>>> un-used patches that I need to worry about. After this patchset, > > >>>> klp_patches will include patches that have been enabled and those that > > >>>> have been replaced, but the replacement transition is still in progress. > > >>>> > > >>>> If that sounds accurate, how about adding to the comment: > > >>>> > > >>>> /* Actively used patches: enabled or replaced and awaiting transition */ > > >>> > > >>> The replaced patches are not in the list. This is why I used the word > > >>> "actively". > > >> > > > > After writing out my suggestion I realized that's why you chose > > "actively" and almost erased my comment. I think the extra text would > > help a fresh reader of the code, so ... > > > > >> The replaced patches are removed in klp_discard_replaced_patches(), which > > >> is called from klp_complete_transition(). Joe is right. The patches are in > > >> the list if a transition is still in progress. > > > > > > These are patches that are being replaced. The replaced (after the > > > transition finishes) are not in the list. > > > > > > By other word, Joe's text could be understand that replaced patches > > > will never get removed from the list. > > > > > > So, is the text below acceptable? > > > > > > /* > > > * Actively used patches: enabled or in transition. Note that replaced > > > * or disabled patches are not listed even though the related kernel > > > * module still can be loaded. > > > */ > > > > Yes this works and is more accurate than my original suggestion. > > >From my perspective, no comment is needed at all, and _any_ comment just > serves to add confusion -- including the above one. But maybe that's > because I already know that disabled and replace patches get discarded. Exactly. If I saw this code for the first time, I would find this comment useful. I often miss these top-level descriptions because they help to get the picture about the code design. Finally, the usage of the list has similar complexity as the use of klp_mutex. There mutex has even longer comment. I will use the longer text if you are not strictly against. Best Regrds, Petr
