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

arch/mips/cavium-octeon/octeon-irq.c

@@ -263,7 +263,7 @@ static int next_cpu_for_irq(struct irq_data *data)
 
 #ifdef CONFIG_SMP
 	int cpu;
-	struct cpumask *mask = irq_data_get_affinity_mask(data);
+	const struct cpumask *mask = irq_data_get_affinity_mask(data);
 	int weight = cpumask_weight(mask);
 	struct octeon_ciu_chip_data *cd = irq_data_get_irq_chip_data(data);
 
@@ -758,7 +758,7 @@ static void octeon_irq_cpu_offline_ciu(struct irq_data *data)
 {
 	int cpu = smp_processor_id();
 	cpumask_t new_affinity;
-	struct cpumask *mask = irq_data_get_affinity_mask(data);
+	const struct cpumask *mask = irq_data_get_affinity_mask(data);
 
 	if (!cpumask_test_cpu(cpu, mask))
 		return;

arch/sh/kernel/irq.c

@@ -230,17 +230,18 @@ void migrate_irqs(void)
 		struct irq_data *data = irq_get_irq_data(irq);
 
 		if (irq_data_get_node(data) == cpu) {
-			struct cpumask *mask = irq_data_get_affinity_mask(data);
+			const struct cpumask *mask = irq_data_get_affinity_mask(data);
 			unsigned int newcpu = cpumask_any_and(mask,
 							      cpu_online_mask);
 			if (newcpu >= nr_cpu_ids) {
 				pr_info_ratelimited("IRQ%u no longer affine to CPU%u\n",
 						    irq, cpu);
 
-				cpumask_setall(mask);
-			}
+				irq_set_affinity(irq, cpu_all_mask);
+			} else {
 				irq_set_affinity(irq, mask);
 			}
 		}
 	}
+}
 #endif

arch/x86/hyperv/irqdomain.c

@@ -192,7 +192,7 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 	struct pci_dev *dev;
 	struct hv_interrupt_entry out_entry, *stored_entry;
 	struct irq_cfg *cfg = irqd_cfg(data);
-	cpumask_t *affinity;
+	const cpumask_t *affinity;
 	int cpu;
 	u64 status;
 

arch/xtensa/kernel/irq.c

@@ -169,7 +169,7 @@ void migrate_irqs(void)
 
 	for_each_active_irq(i) {
 		struct irq_data *data = irq_get_irq_data(i);
-		struct cpumask *mask;
+		const struct cpumask *mask;
 		unsigned int newcpu;
 
 		if (irqd_is_per_cpu(data))
@@ -185,9 +185,10 @@ void migrate_irqs(void)
 			pr_info_ratelimited("IRQ%u no longer affine to CPU%u\n",
 					    i, cpu);
 
-			cpumask_setall(mask);
-		}
+			irq_set_affinity(i, cpu_all_mask);
+		} else {
 			irq_set_affinity(i, mask);
 		}
 	}
+}
 #endif /* CONFIG_HOTPLUG_CPU */

drivers/iommu/hyperv-iommu.c

@@ -194,7 +194,7 @@ hyperv_root_ir_compose_msi_msg(struct irq_data *irq_data, struct msi_msg *msg)
 	u32 vector;
 	struct irq_cfg *cfg;
 	int ioapic_id;
-	struct cpumask *affinity;
+	const struct cpumask *affinity;
 	int cpu;
 	struct hv_interrupt_entry entry;
 	struct hyperv_root_ir_data *data = irq_data->chip_data;

drivers/pci/controller/pci-hyperv.c

@@ -642,7 +642,7 @@ static void hv_arch_irq_unmask(struct irq_data *data)
 	struct hv_retarget_device_interrupt *params;
 	struct tran_int_desc *int_desc;
 	struct hv_pcibus_device *hbus;
-	struct cpumask *dest;
+	const struct cpumask *dest;
 	cpumask_var_t tmp;
 	struct pci_bus *pbus;
 	struct pci_dev *pdev;
@@ -1613,7 +1613,7 @@ static void hv_pci_compose_compl(void *context, struct pci_response *resp,
 }
 
 static u32 hv_compose_msi_req_v1(
-	struct pci_create_interrupt *int_pkt, struct cpumask *affinity,
+	struct pci_create_interrupt *int_pkt, const struct cpumask *affinity,
 	u32 slot, u8 vector, u8 vector_count)
 {
 	int_pkt->message_type.type = PCI_CREATE_INTERRUPT_MESSAGE;
@@ -1641,7 +1641,7 @@ static int hv_compose_msi_req_get_cpu(struct cpumask *affinity)
 }
 
 static u32 hv_compose_msi_req_v2(
-	struct pci_create_interrupt2 *int_pkt, struct cpumask *affinity,
+	struct pci_create_interrupt2 *int_pkt, const struct cpumask *affinity,
 	u32 slot, u8 vector, u8 vector_count)
 {
 	int cpu;
@@ -1660,7 +1660,7 @@ static u32 hv_compose_msi_req_v2(
 }
 
 static u32 hv_compose_msi_req_v3(
-	struct pci_create_interrupt3 *int_pkt, struct cpumask *affinity,
+	struct pci_create_interrupt3 *int_pkt, const struct cpumask *affinity,
 	u32 slot, u32 vector, u8 vector_count)
 {
 	int cpu;
@@ -1697,7 +1697,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 	struct hv_pci_dev *hpdev;
 	struct pci_bus *pbus;
 	struct pci_dev *pdev;
-	struct cpumask *dest;
+	const struct cpumask *dest;
 	struct compose_comp_ctxt comp;
 	struct tran_int_desc *int_desc;
 	struct msi_desc *msi_desc;

include/linux/irq.h

@@ -879,7 +879,8 @@ static inline int irq_data_get_node(struct irq_data *d)
 	return irq_common_data_get_node(d->common);
 }
 
-static inline struct cpumask *irq_data_get_affinity_mask(struct irq_data *d)
+static inline
+const struct cpumask *irq_data_get_affinity_mask(struct irq_data *d)
 {
 	return d->common->affinity;
 }
@@ -890,7 +891,7 @@ static inline void irq_data_update_affinity(struct irq_data *d,
 	cpumask_copy(d->common->affinity, m);
 }
 
-static inline struct cpumask *irq_get_affinity_mask(int irq)
+static inline const struct cpumask *irq_get_affinity_mask(int irq)
 {
 	struct irq_data *d = irq_get_irq_data(irq);
 
@@ -899,7 +900,7 @@ static inline struct cpumask *irq_get_affinity_mask(int irq)
 
 #ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
 static inline
-struct cpumask *irq_data_get_effective_affinity_mask(struct irq_data *d)
+const struct cpumask *irq_data_get_effective_affinity_mask(struct irq_data *d)
 {
 	return d->common->effective_affinity;
 }
@@ -914,13 +915,14 @@ static inline void irq_data_update_effective_affinity(struct irq_data *d,
 {
 }
 static inline
-struct cpumask *irq_data_get_effective_affinity_mask(struct irq_data *d)
+const struct cpumask *irq_data_get_effective_affinity_mask(struct irq_data *d)
 {
 	return irq_data_get_affinity_mask(d);
 }
 #endif
 
-static inline struct cpumask *irq_get_effective_affinity_mask(unsigned int irq)
+static inline
+const struct cpumask *irq_get_effective_affinity_mask(unsigned int irq)
 {
 	struct irq_data *d = irq_get_irq_data(irq);
 

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;

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));

kernel/irq/ipi.c

@@ -115,11 +115,11 @@ int irq_reserve_ipi(struct irq_domain *domain,
 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;