1 files changed, 48 insertions, 15 deletions

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 9ed29ff10e59..10721a125226 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -256,26 +256,59 @@ static __always_inline void handle_irq(struct irq_desc *desc,
 		__handle_irq(desc, regs);
 }
 
-static __always_inline int call_irq_handler(int vector, struct pt_regs *regs)
+static struct irq_desc *reevaluate_vector(int vector)
 {
-	struct irq_desc *desc;
-	int ret = 0;
+	struct irq_desc *desc = __this_cpu_read(vector_irq[vector]);
+
+	if (!IS_ERR_OR_NULL(desc))
+		return desc;
+
+	if (desc == VECTOR_UNUSED)
+		pr_emerg_ratelimited("No irq handler for %d.%u\n", smp_processor_id(), vector);
+	else
+		__this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
+	return NULL;
+}
+
+static __always_inline bool call_irq_handler(int vector, struct pt_regs *regs)
+{
+	struct irq_desc *desc = __this_cpu_read(vector_irq[vector]);
 
-	desc = __this_cpu_read(vector_irq[vector]);
 	if (likely(!IS_ERR_OR_NULL(desc))) {
 		handle_irq(desc, regs);
-	} else {
-		ret = -EINVAL;
-		if (desc == VECTOR_UNUSED) {
-			pr_emerg_ratelimited("%s: %d.%u No irq handler for vector\n",
-					     __func__, smp_processor_id(),
-					     vector);
-		} else {
-			__this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
-		}
+		return true;
 	}
 
-	return ret;
+	/*
+	 * Reevaluate with vector_lock held to prevent a race against
+	 * request_irq() setting up the vector:
+	 *
+	 * CPU0				CPU1
+	 *				interrupt is raised in APIC IRR
+	 *				but not handled
+	 * free_irq()
+	 *   per_cpu(vector_irq, CPU1)[vector] = VECTOR_SHUTDOWN;
+	 *
+	 * request_irq()		common_interrupt()
+	 *				  d = this_cpu_read(vector_irq[vector]);
+	 *
+	 * per_cpu(vector_irq, CPU1)[vector] = desc;
+	 *
+	 *				  if (d == VECTOR_SHUTDOWN)
+	 *				    this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
+	 *
+	 * This requires that the same vector on the same target CPU is
+	 * handed out or that a spurious interrupt hits that CPU/vector.
+	 */
+	lock_vector_lock();
+	desc = reevaluate_vector(vector);
+	unlock_vector_lock();
+
+	if (!desc)
+		return false;
+
+	handle_irq(desc, regs);
+	return true;
 }
 
 /*
@@ -289,7 +322,7 @@ DEFINE_IDTENTRY_IRQ(common_interrupt)
 	/* entry code tells RCU that we're not quiescent.  Check it. */
 	RCU_LOCKDEP_WARN(!rcu_is_watching(), "IRQ failed to wake up RCU");
 
-	if (unlikely(call_irq_handler(vector, regs)))
+	if (unlikely(!call_irq_handler(vector, regs)))
 		apic_eoi();
 
 	set_irq_regs(old_regs);