On 2023/3/27 7:25, Christoph Hellwig wrote: > On Sun, Mar 26, 2023 at 01:53:27PM +0900, Sergey Senozhatsky wrote: >>>> + if (kstrtobool(val, &res)) >>>> + return -EINVAL; >>>> + >>>> + /* no change required */ >>>> + if (res == *(bool *)kp->arg) >>>> + return 0; >>> Bool kernel param can be any of these letters 'YyTt1NnFf0'. Doing things >>> to kp->arg outside of kernel/params.c is not going to be easy, let's not >>> even try. >> Please disregard my previous email. kp->arg is always true or false >> at this point. I'd still prefer to not do kp->arg in zswap. > The whole parameter handling in zswap is a mess and I don't really > have a good idea how to solve it all. > > But for this "paramter not changed" case I think we can helper a lot > by adding a core moduleparam.h helper to encapsule it. I.e.: > > static inline bool param_bool_unchanged(bool val, > const struct kernel_param *kp) > > return val == *(bool *)kp->arg); > } > > and at least keep it out of zswap. Thanks for your advice. I will try this way. > > . >
