init_irq_stacks() and init_irq_scs() may fail when arch_alloc_vmap_stack
or scs_alloc return NULL. Return -ENOMEM from both and call panic() once
from init_IRQ(), covering per-CPU IRQ stacks and shadow IRQ stacks
consistently.

Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
---
v2:
- Add return -ENOMEM from both init_irq_stacks() and init_irq_scs()
- Call panic() once from init_IRQ() if either init_irq_stacks() or
  init_irq_scs() returns -ENOMEM
---
 arch/arm64/kernel/irq.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index 15dedb385b9e..9fafd826002b 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -10,6 +10,7 @@
  * Copyright (C) 2012 ARM Ltd.
  */
 
+#include <linux/errno.h>
 #include <linux/hardirq.h>
 #include <linux/init.h>
 #include <linux/irq.h>
@@ -32,34 +33,43 @@ DEFINE_PER_CPU(struct nmi_ctx, nmi_contexts);
 
 DEFINE_PER_CPU(unsigned long *, irq_stack_ptr);
 
-
 DECLARE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);
 
 #ifdef CONFIG_SHADOW_CALL_STACK
 DEFINE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);
 #endif
 
-static void init_irq_scs(void)
+static int __init init_irq_scs(void)
 {
 	int cpu;
+	void *s;
 
 	if (!scs_is_enabled())
-		return;
+		return 0;
+
+	for_each_possible_cpu(cpu) {
+		s = scs_alloc(early_cpu_to_node(cpu));
+		if (!s)
+			return -ENOMEM;
+		per_cpu(irq_shadow_call_stack_ptr, cpu) = s;
+	}
 
-	for_each_possible_cpu(cpu)
-		per_cpu(irq_shadow_call_stack_ptr, cpu) =
-			scs_alloc(early_cpu_to_node(cpu));
+	return 0;
 }
 
-static void __init init_irq_stacks(void)
+static int __init init_irq_stacks(void)
 {
 	int cpu;
 	unsigned long *p;
 
 	for_each_possible_cpu(cpu) {
 		p = arch_alloc_vmap_stack(IRQ_STACK_SIZE, early_cpu_to_node(cpu));
+		if (!p)
+			return -ENOMEM;
 		per_cpu(irq_stack_ptr, cpu) = p;
 	}
+
+	return 0;
 }
 
 #ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
@@ -109,8 +119,9 @@ int __init set_handle_fiq(void (*handle_fiq)(struct pt_regs *))
 
 void __init init_IRQ(void)
 {
-	init_irq_stacks();
-	init_irq_scs();
+	if (init_irq_stacks() || init_irq_scs())
+		panic("Failed to allocate IRQ stack resources\n");
+
 	irqchip_init();
 
 	if (system_uses_irq_prio_masking()) {
-- 
2.43.0