Messages in this thread Patch in this message | | | Date | Fri, 16 Dec 2022 11:46:14 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2] sched: Make const-safe |
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On Wed, Dec 14, 2022 at 06:03:04PM +0000, Matthew Wilcox wrote: > On Wed, Dec 14, 2022 at 10:11:01AM +0100, Peter Zijlstra wrote: > > On Mon, Dec 12, 2022 at 02:49:46PM +0000, Matthew Wilcox (Oracle) wrote: > > > With a modified container_of() that preserves constness, the compiler > > > finds some pointers which should have been marked as const. task_of() > > > also needs to become const-preserving for the !FAIR_GROUP_SCHED case so > > > that cfs_rq_of() can take a const argument. No change to generated code. > > > > More const more better I suppose.. Thanks! > > > > Happen to have a sha for the container_of() commit handy? > > There isn't one yet. Obviously we can't make container_of() > const-preserving until we've fixed all the places which would warn. > The diff I have in my tree looks like this: > > diff --git a/include/linux/container_of.h b/include/linux/container_of.h > index 1d898f9158b4..9416e6cc8c88 100644 > --- a/include/linux/container_of.h > +++ b/include/linux/container_of.h > @@ -20,7 +20,10 @@ > static_assert(__same_type(*(ptr), ((type *)0)->member) || \ > __same_type(*(ptr), void), \ > "pointer type mismatch in container_of()"); \ > - ((type *)(__mptr - offsetof(type, member))); }) > + __mptr -= offsetof(type, member); \ > + _Generic(ptr, \ > + const typeof(*(ptr)) *: (const type *)__mptr, \ > + default: ((type *)__mptr)); })
Ah nice. Thanks!
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