x86/apic: Provide apic_ack_irq()

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@linutronix.de>
Tested-by: Song Liu <songliubraving@fb.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <liu.song.a23@gmail.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: stable@vger.kernel.org
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Tariq Toukan <tariqt@mellanox.com>
Link: https://lkml.kernel.org/r/20180604162224.471925894@linutronix.de

2 files changed, 9 insertions, 2 deletions

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 08acd954f00e..74a9e06b6cfd 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -436,6 +436,8 @@ static inline void apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v)) {}
 
 #endif /* CONFIG_X86_LOCAL_APIC */
 
+extern void apic_ack_irq(struct irq_data *data);
+
 static inline void ack_APIC_irq(void)
 {
         /*
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 72b575a0b662..b708f597eee3 100644
--- 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_data *irqd)
         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,