genirq: Add and use an irq_data_update_affinity helper

[ Upstream commit 073352e951f60946452da358d64841066c3142ff ]

Some architectures and irqchip drivers modify the cpumask returned by
irq_data_get_affinity_mask, usually by copying in to it. This is
problematic for uniprocessor configurations, where the affinity mask
should be constant, as it is known at compile time.

Add and use a setter for the affinity mask, following the pattern of
irq_data_update_effective_affinity. This allows the getter function to
return a const cpumask pointer.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # Xen bits
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220701200056.46555-7-samuel@sholland.org
Stable-dep-of: feabecaff590 ("genirq/ipi: Fix NULL pointer deref in irq_data_get_affinity_mask()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 5f8f0f24a280..f9e6449fbbba 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -880,6 +880,12 @@ static inline struct cpumask *irq_data_get_affinity_mask(struct irq_data *d)
 	return d->common->affinity;
 }
 
+static inline void irq_data_update_affinity(struct irq_data *d,
+					    const struct cpumask *m)
+{
+	cpumask_copy(d->common->affinity, m);
+}
+
 static inline struct cpumask *irq_get_affinity_mask(int irq)
 {
 	struct irq_data *d = irq_get_irq_data(irq);