genirq: Fix the return type of kstat_cpu_irqs_sum()

The type of member ->irqs_sum is unsigned long, but kstat_cpu_irqs_sum()
returns int, which can result in truncation.  Therefore, change the
kstat_cpu_irqs_sum() function's return value to unsigned long to avoid
truncation.

Fixes: f2c66cd ("/proc/stat: scalability of irq num per cpu")
Reported-by: Elliott, Robert (Servers) <[email protected]>
Signed-off-by: Zhen Lei <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: "Peter Zijlstra (Intel)" <[email protected]>
Cc: Josh Don <[email protected]>
Cc: Andrew Morton <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

Author: Zhen Lei

include/linux/kernel_stat.h

@@ -75,7 +75,7 @@ extern unsigned int kstat_irqs_usr(unsigned int irq);
 /*
  * Number of interrupts per cpu, since bootup
  */
-static inline unsigned int kstat_cpu_irqs_sum(unsigned int cpu)
+static inline unsigned long kstat_cpu_irqs_sum(unsigned int cpu)
 {
 	return kstat_cpu(cpu).irqs_sum;
 }