From 50a209eab17fbf04bc7316dfa3ccf3a3b504271f Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 19 Jul 2018 21:50:23 +0200
Subject: [PATCH 415/518] x86/ioapic: Don't let setaffinity unmask threaded EOI
 interrupt too early

[ Upstream commit ac14002317721910204b82b9d8611dadb1cec2bb ]

There is an issue with threaded interrupts which are marked ONESHOT
and using the fasteoi handler.

    if (IS_ONESHOT())
        mask_irq();

    ....
    ....

    cond_unmask_eoi_irq()
        chip->irq_eoi();

So if setaffinity is pending then the interrupt will be moved and then
unmasked, which is wrong as it should be kept masked up to the point where
the threaded handler finished. It's not a real problem, the interrupt will
just be able to fire before the threaded handler has finished, though the irq
masked state will be wrong for a bit.

The patch below should cure the issue. It also renames the horribly
misnomed functions so it becomes clear what they are supposed to do.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[bigeasy: add the body of the patch, use the same functions in both
          ifdef paths (spotted by Andy Shevchenko)]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 arch/x86/kernel/apic/io_apic.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 1cceb30357aaf..3e173886b2c64 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1698,7 +1698,7 @@ static bool io_apic_level_ack_pending(struct mp_chip_data *data)
 	return false;
 }
 
-static inline bool ioapic_irqd_mask(struct irq_data *data)
+static inline bool ioapic_prepare_move(struct irq_data *data)
 {
 	/* If we are moving the IRQ we need to mask it */
 	if (unlikely(irqd_is_setaffinity_pending(data))) {
@@ -1709,9 +1709,9 @@ static inline bool ioapic_irqd_mask(struct irq_data *data)
 	return false;
 }
 
-static inline void ioapic_irqd_unmask(struct irq_data *data, bool masked)
+static inline void ioapic_finish_move(struct irq_data *data, bool moveit)
 {
-	if (unlikely(masked)) {
+	if (unlikely(moveit)) {
 		/* Only migrate the irq if the ack has been received.
 		 *
 		 * On rare occasions the broadcast level triggered ack gets
@@ -1746,11 +1746,11 @@ static inline void ioapic_irqd_unmask(struct irq_data *data, bool masked)
 	}
 }
 #else
-static inline bool ioapic_irqd_mask(struct irq_data *data)
+static inline bool ioapic_prepare_move(struct irq_data *data)
 {
 	return false;
 }
-static inline void ioapic_irqd_unmask(struct irq_data *data, bool masked)
+static inline void ioapic_finish_move(struct irq_data *data, bool moveit)
 {
 }
 #endif
@@ -1759,11 +1759,11 @@ static void ioapic_ack_level(struct irq_data *irq_data)
 {
 	struct irq_cfg *cfg = irqd_cfg(irq_data);
 	unsigned long v;
-	bool masked;
+	bool moveit;
 	int i;
 
 	irq_complete_move(cfg);
-	masked = ioapic_irqd_mask(irq_data);
+	moveit = ioapic_prepare_move(irq_data);
 
 	/*
 	 * It appears there is an erratum which affects at least version 0x11
@@ -1818,7 +1818,7 @@ static void ioapic_ack_level(struct irq_data *irq_data)
 		eoi_ioapic_pin(cfg->vector, irq_data->chip_data);
 	}
 
-	ioapic_irqd_unmask(irq_data, masked);
+	ioapic_finish_move(irq_data, moveit);
 }
 
 static void ioapic_ir_ack_level(struct irq_data *irq_data)
-- 
2.41.0

