On Wed, Sep 18, 2002 at 10:58:10AM -0700, KONG, Gangfeng wrote: > At 10:01 AM 9/18/2002 +0530, Nagaraj wrote: > > >From: "KONG, Gangfeng" <gkong@IPRG.nokia.com>: > >> Hi, > >> > >> I am debugging a kernel module. Any error in it is easy to make > >> the module unloadable ( complaining: Device or resource busy). > >> Is there anyway to unload a sick LKM without rebooting? > >> > >> Thanks > >> GF > >> > >When u r developing the module, dont use > >MOD_INC_USE_COUNT and DEC counts. > > > >When ur application crashes, it wont complain about > >module being busy. > > > >Once ur module is entirely tested, u keep these > >in open and closes. > > > >However this is not a solution if ur module itself > >has some bugs and lets say crashes during > >init_module(). > > Hi, > > Unfortunately, my LKM is not a driver, it's extended kernel functions. > Some memory error does happen in init_module(). I have fixed the errors, > but every time has to reboot. I also tried to rename the LKM as john > suggested, also doesn't work. It looks like kmem_cache_xxx functions > keeping error status, can not self recovery. Wait...a...moment. What is the interface to these functions? As kernel itself is staticaly linked, these functions may either be available by resolving from other module - in which case the calling module holds the count just by having the names resolved, or function pointers must be in some structure - in which case the structure must have properly used owner field. Anyway, if the module screws up and cannot be unloaded, you need to somehow need to change kernels idea of what may be unloaded. There is a function, that, if defined, is called to tell if the module is busy. So you can define this function to always claim module can be unloaded during development. Note, that if you fail to clean up things (like mem caches) in the cleanup function, module won't load again, because some init may fail. Also note, that unloading a module while you fail to remove all references to it will lead to OOPS or panic sooner or later. Consider developing the module under the user-mode-linux. It allows to debug all the arch-independent stuff in a user-mode process, so you just reboot the user-mode kernel (which may have almost empty rc scripts) instead of the whole system. In addition, it's possible to debug it using gdb (though some internal magic is involved there). As you say that it's not a driver, this might very well be an option for you. ------------------------------------------------------------------------------- Jan 'Bulb' Hudec <bulb@ucw.cz> -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
