irq: call __irq_enter() before calling the tick_idle_check

Impact: avoid spurious ksoftirqd wakeups

The tick idle check which is called from irq_enter() was run before
the call to __irq_enter() which did not set the in_interrupt() bits in
preempt_count. That way the raise of a softirq woke up softirqd for
nothing as the softirq was handled on return from interrupt.

Call __irq_enter() before calling into the tick idle check code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 3 deletions

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 7110daeb9a9..e7c69a720d6 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -269,10 +269,11 @@ void irq_enter(void)
 {
         int cpu = smp_processor_id();
 
-        if (idle_cpu(cpu) && !in_interrupt())
+        if (idle_cpu(cpu) && !in_interrupt()) {
+                __irq_enter();
                 tick_check_idle(cpu);
-
-        __irq_enter();
+        } else
+                __irq_enter();
 }
 
 #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED