On 2021/10/13 上午10:30, Steven Rostedt wrote: > On Wed, 13 Oct 2021 10:04:52 +0800 > 王贇 <yun.wang@xxxxxxxxxxxxxxxxx> wrote: > >> I see, while the user can still check smp_processor_id() after trylock >> return bit 0... > > But preemption would have already been disabled. That's because a bit 0 > means that a recursion check has already been made by a previous > caller and this one is nested, thus preemption is already disabled. > If bit is 0, then preemption had better be disabled as well. Thanks for the explain, now I get your point :-) Let's make bit 0 an exemption then. Regards, Michael Wang > > -- Steve >
