arch/powerpc/include/asm/membarrier.h

   1 #ifndef _ASM_POWERPC_MEMBARRIER_H
   2 #define _ASM_POWERPC_MEMBARRIER_H
   3
   4 static inline void membarrier_arch_switch_mm(struct mm_struct *prev,
   5                                              struct mm_struct *next,
   6                                              struct task_struct *tsk)
   7 {
   8         /*
   9          * Only need the full barrier when switching between processes.
  10          * Barrier when switching from kernel to userspace is not
  11          * required here, given that it is implied by mmdrop(). Barrier
  12          * when switching from userspace to kernel is not needed after
  13          * store to rq->curr.
  14          */
  15         if (likely(!(atomic_read(&next->membarrier_state) &
  16                      (MEMBARRIER_STATE_PRIVATE_EXPEDITED |
  17                       MEMBARRIER_STATE_GLOBAL_EXPEDITED)) || !prev))
  18                 return;
  19
  20         /*
  21          * The membarrier system call requires a full memory barrier
  22          * after storing to rq->curr, before going back to user-space.
  23          */
  24         smp_mb();
  25 }
  26
  27 #endif /* _ASM_POWERPC_MEMBARRIER_H */