Re: [PATCH RFC v3 02/10] sched_getattr: port to copy_struct_to_user

From: Florian Weimer
Date: Tue Dec 10 2024 - 13:14:32 EST


* Aleksa Sarai:

> sched_getattr(2) doesn't care about trailing non-zero bytes in the
> (ksize > usize) case, so just use copy_struct_to_user() without checking
> ignored_trailing.

I think this is what causes glibc's misc/tst-sched_setattr test to fail
on recent kernels. The previous non-modifying behavior was documented
in the manual page:

If the caller-provided attr buffer is larger than the kernel's
sched_attr structure, the additional bytes in the user-space
structure are not touched.

I can just drop this part of the test if the kernel deems both behaviors
valid.

Thanks,
Florian