On Wed, Jul 21, 2021 at 7:26 AM Nitesh Narayan Lal <nitesh@xxxxxxxxxx> wrote: > > From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > The discussion about removing the side effect of irq_set_affinity_hint() of > actually applying the cpumask (if not NULL) as affinity to the interrupt, > unearthed a few unpleasantries: > > 1) The modular perf drivers rely on the current behaviour for the very > wrong reasons. > > 2) While none of the other drivers prevents user space from changing > the affinity, a cursorily inspection shows that there are at least > expectations in some drivers. > > #1 needs to be cleaned up anyway, so that's not a problem > > #2 might result in subtle regressions especially when irqbalanced (which > nowadays ignores the affinity hint) is disabled. > > Provide new interfaces: > > irq_update_affinity_hint() - Only sets the affinity hint pointer > irq_set_affinity_and_hint() - Set the pointer and apply the affinity to > the interrupt > > Make irq_set_affinity_hint() a wrapper around irq_apply_affinity_hint() and > document it to be phased out. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Signed-off-by: Nitesh Narayan Lal <nitesh@xxxxxxxxxx> > Link: https://lore.kernel.org/r/20210501021832.743094-1-jesse.brandeburg@xxxxxxxxx Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
