Messages in this thread | | | Date | Tue, 23 Jul 2002 08:42:00 -0400 | From | Brian Gerst <> | Subject | Re: PATCH: type safe(r) list_entry repacement: generic_out_cast |
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remove-irqlock-2.5.27-F3Neil Brown wrote: > list.h has this nifty macro called list_entry that takes a pointer to a "struct > list_head" and "casts" that to a pointer to some structure that > contains the "struct list_head". > > However it doesn't do any type checking on the pointer, and you can > give it a pointer to something else... just as I did in line 850 of > md/md.c :-( > > So I thought I would add some type checking to list_entry so that > you have to pass it a "struct list_head *", but I then discovered that > lots of places are using list_entry to do creative casting on > all sorts of other things like inodes embedded in bigger structures > and so on. > > So... I have created "generic_out_cast" which is like the old > list_entry but with an extra type arguement. I have then > changed uses of list_entry that did not actually apply to lists to use > generic_out_cast, often indirectly. > > Why "out_cast"??? > > Well OO people would probably call it a "down cast" as you are > effectively casting from a more-general type to a less-general (more > specific) type that is there-fore lower on the type latice. > So maybe it should be "generic_down_cast". > But seeing that one is casting from an embeded internal structure to a > containing external structure, "out_cast" seemed a little easier to > intuitively understand. > > If anyone wants to suggest better names of any of the names I have > chosen, feel free to submit suggestions or patches.
How about member_to_struct() or unembed()?
-- Brian Gerst
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