[DTrace-devel] [PATCH v2 07/11] htab reduction: kernpath

[Kris Van Hees]

On Fri, Oct 22, 2021 at 12:31:56PM -0400, Eugene Loh wrote:
> On 10/22/21 1:39 AM, Kris Van Hees wrote:
> 
> > On Fri, Oct 22, 2021 at 12:15:51AM -0400, Eugene Loh wrote:
> >> There is, however, some other consistency that might be reasonable in
> >> these various patches.  E.g., in dt_htab.h, del always comes before
> >> next.  So, how about using the same order in other files as well -- that
> >> is, wherever "dt_htab_ops_t *_htab_ops" are defined.
> >>
> >> But come to think of it, when you define delete functions that free
> >> resources, you append customized suffixes:  del_buf, del_path, del_mod,
> >> and del_prov.  Why?  How about making them all del_res (or something).
> >> Then, the dt_htab_ops_t definitions can all use a common macro:
> >> DEFINE_HTAB_STD_OPS_RES(ID) (or something like that).
> > Why not simply del?  Whether a delete function has other resources to free
> > or not shouldn't matter to the htab implementation.  You call the op to
> > delete the element, and the implementation of the ops will do what is needed
> > for that particular type.
> Hmm, yeah, good point.  But the delete function has the 
> doubly-linked-list pointer manipulation to do in any case, and that is 
> set up by the DEFINE_HE_STD_LINK_FUNCS macro.  So, I think the idea is 
> to take advantage of that boilerplate setup and to add a differently 
> named function as well in the case that there are other resources to 
> free.  Otherwise, one is defining a del() function that cuts and pastes 
> lots of pointer management in.

Well, you can still define the standard link functions.  And then define a
cusstom del_*() function that calls the *_del() function for the linking
work to be done, and does the resource freeing.  And register that del_*()
custom one as the .del hook.