genirq: Return a const cpumask from irq_data_get_affinity_mask

Now that the irq_data_update_affinity helper exists, enforce its use
by returning a a const cpumask from irq_data_get_affinity_mask.

Since the previous commit already updated places that needed to call
irq_data_update_affinity, this commit updates the remaining code that
either did not modify the cpumask or immediately passed the modified
mask to irq_set_affinity.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220701200056.46555-8-samuel@sholland.org

3 files changed, 15 insertions, 11 deletions

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 886789dcee43..9c7ad2266317 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -188,7 +188,8 @@ enum {
 
 #ifdef CONFIG_SMP
 static int
-__irq_startup_managed(struct irq_desc *desc, struct cpumask *aff, bool force)
+__irq_startup_managed(struct irq_desc *desc, const struct cpumask *aff,
+		      bool force)
 {
 	struct irq_data *d = irq_desc_get_irq_data(desc);
 
@@ -224,7 +225,8 @@ __irq_startup_managed(struct irq_desc *desc, struct cpumask *aff, bool force)
 }
 #else
 static __always_inline int
-__irq_startup_managed(struct irq_desc *desc, struct cpumask *aff, bool force)
+__irq_startup_managed(struct irq_desc *desc, const struct cpumask *aff,
+		      bool force)
 {
 	return IRQ_STARTUP_NORMAL;
 }
@@ -252,7 +254,7 @@ static int __irq_startup(struct irq_desc *desc)
 int irq_startup(struct irq_desc *desc, bool resend, bool force)
 {
 	struct irq_data *d = irq_desc_get_irq_data(desc);
-	struct cpumask *aff = irq_data_get_affinity_mask(d);
+	const struct cpumask *aff = irq_data_get_affinity_mask(d);
 	int ret = 0;
 
 	desc->depth = 0;
diff --git a/kernel/irq/debugfs.c b/kernel/irq/debugfs.c
index bc8e40cf2b65..bbcaac64038e 100644
--- a/kernel/irq/debugfs.c
+++ b/kernel/irq/debugfs.c
@@ -30,7 +30,7 @@ static void irq_debug_show_bits(struct seq_file *m, int ind, unsigned int state,
 static void irq_debug_show_masks(struct seq_file *m, struct irq_desc *desc)
 {
 	struct irq_data *data = irq_desc_get_irq_data(desc);
-	struct cpumask *msk;
+	const struct cpumask *msk;
 
 	msk = irq_data_get_affinity_mask(data);
 	seq_printf(m, "affinity: %*pbl\n", cpumask_pr_args(msk));
diff --git a/kernel/irq/ipi.c b/kernel/irq/ipi.c
index 08ce7da3b57c..bbd945bacef0 100644
--- a/kernel/irq/ipi.c
+++ b/kernel/irq/ipi.c
@@ -115,11 +115,11 @@ free_descs:
 int irq_destroy_ipi(unsigned int irq, const struct cpumask *dest)
 {
 	struct irq_data *data = irq_get_irq_data(irq);
-	struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
+	const struct cpumask *ipimask;
 	struct irq_domain *domain;
 	unsigned int nr_irqs;
 
-	if (!irq || !data || !ipimask)
+	if (!irq || !data)
 		return -EINVAL;
 
 	domain = data->domain;
@@ -131,7 +131,8 @@ int irq_destroy_ipi(unsigned int irq, const struct cpumask *dest)
 		return -EINVAL;
 	}
 
-	if (WARN_ON(!cpumask_subset(dest, ipimask)))
+	ipimask = irq_data_get_affinity_mask(data);
+	if (!ipimask || WARN_ON(!cpumask_subset(dest, ipimask)))
 		/*
 		 * Must be destroying a subset of CPUs to which this IPI
 		 * was set up to target
@@ -162,12 +163,13 @@ int irq_destroy_ipi(unsigned int irq, const struct cpumask *dest)
 irq_hw_number_t ipi_get_hwirq(unsigned int irq, unsigned int cpu)
 {
 	struct irq_data *data = irq_get_irq_data(irq);
-	struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
+	const struct cpumask *ipimask;
 
-	if (!data || !ipimask || cpu >= nr_cpu_ids)
+	if (!data || cpu >= nr_cpu_ids)
 		return INVALID_HWIRQ;
 
-	if (!cpumask_test_cpu(cpu, ipimask))
+	ipimask = irq_data_get_affinity_mask(data);
+	if (!ipimask || !cpumask_test_cpu(cpu, ipimask))
 		return INVALID_HWIRQ;
 
 	/*
@@ -186,7 +188,7 @@ EXPORT_SYMBOL_GPL(ipi_get_hwirq);
 static int ipi_send_verify(struct irq_chip *chip, struct irq_data *data,
 			   const struct cpumask *dest, unsigned int cpu)
 {
-	struct cpumask *ipimask = irq_data_get_affinity_mask(data);
+	const struct cpumask *ipimask = irq_data_get_affinity_mask(data);
 
 	if (!chip || !ipimask)
 		return -EINVAL;