On 11/06/2018 06:40 AM, Peter Zijlstra wrote: > On Mon, Oct 15, 2018 at 04:29:30PM -0400, Waiman Long wrote: >> + spin_lock_irq(&callback_lock); >> + clear_bit(CS_CPU_EXCLUSIVE, &cp->flags); >> + spin_unlock_irq(&callback_lock); > A single atomic bitop wrapped in a spinlock.. maybe it is correct, but > it looks suspicous. Yes, you are right. The spin_lock() should not be needed in this case. Thanks, Longman