On Wed, Aug 18, 2021 at 11:50:30AM +0100, Will Deacon wrote: > 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 Clearly that deserves a comment somewhere, because I keep trying to make it more consistent than it can be :/ I'll see if I can find a spot.
