smp: Move irq_work_run() out of flush_smp_call_function_queue()

This ensures flush_smp_call_function_queue() is strictly about
call_single_queue.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200526161907.895109676@infradead.org

kernel/smp.c

@@ -84,6 +84,7 @@ int smpcfd_dying_cpu(unsigned int cpu)
 	 * still pending.
 	 */
 	flush_smp_call_function_queue(false);
+	irq_work_run();
 	return 0;
 }
 
@@ -191,6 +192,14 @@ static int generic_exec_single(int cpu, call_single_data_t *csd,
 void generic_smp_call_function_single_interrupt(void)
 {
 	flush_smp_call_function_queue(true);
+
+	/*
+	 * Handle irq works queued remotely by irq_work_queue_on().
+	 * Smp functions above are typically synchronous so they
+	 * better run first since some other CPUs may be busy waiting
+	 * for them.
+	 */
+	irq_work_run();
 }
 
 /**
@@ -267,14 +276,6 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
 		csd_unlock(csd);
 		func(info);
 	}
-
-	/*
-	 * Handle irq works queued remotely by irq_work_queue_on().
-	 * Smp functions above are typically synchronous so they
-	 * better run first since some other CPUs may be busy waiting
-	 * for them.
-	 */
-	irq_work_run();
 }
 
 /*