On Tue, Aug 17, 2021 at 05:40:24PM +0200, Peter Zijlstra wrote: > On Fri, Jul 30, 2021 at 12:24:34PM +0100, Will Deacon wrote: > > In preparation for replaying user affinity requests using a saved mask, > > split sched_setaffinity() up so that the initial task lookup and > > security checks are only performed when the request is coming directly > > from userspace. > > > > Reviewed-by: Valentin Schneider <Valentin.Schneider@xxxxxxx> > > Signed-off-by: Will Deacon <will@xxxxxxxxxx> > > Should not sched_setaffinity() update user_cpus_ptr when it isn't NULL, > such that the upcoming relax_compatible_cpus_allowed_ptr() preserve the > full user mask? The idea is that force_compatible_cpus_allowed_ptr() and relax_compatible_cpus_allowed_ptr() are used as a pair, with the former setting ->user_cpus_ptr and the latter restoring it. An intervening call to sched_setaffinity() must _clear_ the saved mask, as we discussed before at: https://lore.kernel.org/r/YK53kDtczHIYumDC@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Will
