On Tue, Nov 10, 2020 at 11:21:22AM +0000, Peter Chen wrote: > On 20-11-10 09:20:54, Pawel Laszczak wrote: > > Hi, > > > > >> > > >> int cdns3_hw_role_switch(struct cdns3 *cdns); > > >> -int cdns3_init(struct cdns3 *cdns); > > >> -int cdns3_remove(struct cdns3 *cdns); > > >> +extern int cdns3_init(struct cdns3 *cdns); > > >> +extern int cdns3_remove(struct cdns3 *cdns); > > > > > >Why add "extern" here and below? > > > > > > > These functions are the API between cdnsp and cdns3 modules. > > It's looks like a common approach in kernel. > > Many or even most of API function in kernel has "extern". > > > > Even you have not written "extern" keyword, the "extern" is > added implicitly by compiler. Usually, we use "extern" for variable > or the function is defined at assembly. You could see some > "extern" keyword use cases at include/linux/device.h. We are moving away from using this keyword for functions now, if at all possible please. Only use it for variables, I think checkpatch now catches it as well. thanks, greg k-h
