Linux内核中是否有功能/宏来获取smp计算机上的当前抢占状态？

Question

In my project I use get_cpu() and put_cpu() to disable and enable the preemption in the kernel on a smp machine.

Is there a safe way to get the current preemption status in an smp machine ie whether the preemption is turned on or off.

Answer 1

preempt_count () returns current thread's preemption count. 0 value means that preemtion is allowed.

Usually, you shouldn't request preemtion status unless for the selfcheck. If some block of code requires preemtion to be disabled, it should be wrapped with preempt_disable() / preempt_enable() calls (or their alternatives).