[PATCH 4.16 49/64] x86/apic: Provide apic_ack_irq()

[Greg Kroah-Hartman]

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

commit c0255770ccdc77ef2184d2a0a2e0cde09d2b44a4 upstream.

apic_ack_edge() is explicitely for handling interrupt affinity cleanup when
interrupt remapping is not available or disable.

Remapped interrupts and also some of the platform specific special
interrupts, e.g. UV, invoke ack_APIC_irq() directly.

To address the issue of failing an affinity update with -EBUSY the delayed
affinity mechanism can be reused, but ack_APIC_irq() does not handle
that. Adding this to ack_APIC_irq() is not possible, because that function
is also used for exceptions and directly handled interrupts like IPIs.

Create a new function, which just contains the conditional invocation of
irq_move_irq() and the final ack_APIC_irq().

Reuse the new function in apic_ack_edge().

Preparatory change for the real fix.

Fixes: dccfe3147b42 ("x86/vector: Simplify vector move cleanup")
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Song Liu <songliubraving@xxxxxx>
Cc: Joerg Roedel <jroedel@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Song Liu <liu.song.a23@xxxxxxxxx>
Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: Mike Travis <mike.travis@xxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Tariq Toukan <tariqt@xxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20180604162224.471925894@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/include/asm/apic.h   |    2 ++
 arch/x86/kernel/apic/vector.c |    9 +++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -442,6 +442,8 @@ static inline void apic_set_eoi_write(vo
 
 #endif /* CONFIG_X86_LOCAL_APIC */
 
+extern void apic_ack_irq(struct irq_data *data);
+
 static inline void ack_APIC_irq(void)
 {
 	/*
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -809,13 +809,18 @@ static int apic_retrigger_irq(struct irq
 	return 1;
 }
 
-void apic_ack_edge(struct irq_data *irqd)
+void apic_ack_irq(struct irq_data *irqd)
 {
-	irq_complete_move(irqd_cfg(irqd));
 	irq_move_irq(irqd);
 	ack_APIC_irq();
 }
 
+void apic_ack_edge(struct irq_data *irqd)
+{
+	irq_complete_move(irqd_cfg(irqd));
+	apic_ack_irq(irqd);
+}
+
 static struct irq_chip lapic_controller = {
 	.name			= "APIC",
 	.irq_ack		= apic_ack_edge,