Hi David, Dan and Paul On Wed, 26 Aug 2026 at 15:22, David Laight <[email protected]> wrote: > > On Wed, 26 Aug 2026 13:28:42 +0200 > Ricardo Ribalda <[email protected]> wrote: > > > Hi David > > > > On Wed, 26 Aug 2026 at 11:55, David Laight <[email protected]> > > wrote: > > > > > > On Tue, 25 Aug 2026 20:02:10 +0000 > > > Ricardo Ribalda <[email protected]> wrote: > > > > > > > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > > > > index 44c07a66edff..80276cedda80 100644 > > > > --- a/include/linux/rcupdate.h > > > > +++ b/include/linux/rcupdate.h > > > > @@ -488,7 +488,7 @@ static __always_inline bool > > > > lockdep_assert_rcu_helper(bool c, const struct __ctx > > > > context_unsafe( > > > > \ > > > > typeof(*p) *local = (typeof(*p) *__force)(p); \ > > > > rcu_check_sparse(p, __rcu); \ > > > > - ((typeof(*p) __force __kernel *)(local)) \ > > > > + ((TYPEOF_UNQUAL(*p) __force __kernel *)(local)) \ > > > > > > Ugg... TYPEOF_UNQUAL() is absolutely horrid... > > > When __CHECKER__ is undefined the whole thing is just (p). > > > > About using __CHECKER__: Are you suggesting using #ifdef __CHECKER__ > > to use TYPEOF_UNQUAL or the current code? > > > > I am open to doing that, but I would like to hear from Paul if he > > favors adding the (also horrid) #ifdef to save some CPU cycles on > > older compilers. > > > > > > > > I suspect reducing all the definitions would measurably improve > > > kernel compile time (even before these changes). > > > > When I checked earlier in the other patch in this patchset, with my > > compiler I can hardly see any difference in compilation times [1]. > > This is probably because GCC15 direclty maps TYPEOF_UNQUAL to the > > built-in __typeof_unqual__. > > I was thinking of the _Generic() version. > > But here you only want to remove the (I think) __user marker. > I don't think you want to get rid of 'const'. > So you don't really want gcc to remove any qualifiers.
Yeah, I see your point, removing `const` might hide other issues. Dan, what would be the best "sparse-approved" way of removing the address space qualifiers (__user __rcu) but keeping the other ones (const) ? Paul, would you accept an #ifdef __CHECKER__ block to keep Sparse happy without affecting GCC type checking? Thanks! > > There is an similar(ish) issue when an __force cast is used to > remove one of the extra qualifiers. > You really want the compiler to ignore the cast - so it checks > the actual types match. > > David > > > > > > > Thanks! > > > > > > [1] > > https://lore.kernel.org/all/canidscsmrulsrgqg76x28grxlg+hskfwhha14zcn8hdm4ky...@mail.gmail.com/ > > > > > > > > David > -- Ricardo Ribalda
