On (05/18/18 11:07), Sergey Senozhatsky wrote: > > if (this_cpu_read(printk_context) & PRINTK_SAFE_CONTEXT_MASK) || > raw_spin_is_locked(&logbuf_lock) > > just to check per-CPU `printk_context' first and only afterwards > access the global `logbuf_lock'. printk_nmi_enter() happens on > every CPU, so maybe we can avoid some overhead by checking the > local per-CPU data first. Nah, may be it won't. This, probably, would have been the case if we had continue to call console drivers from printk_safe section [at least]. CPUs don't spend that much time in printk_safe sections. -ss
