On Fri, Jul 18, 2014 at 09:43:48AM +0530, Chetan Nanda wrote: > > > > On Wed, Jul 16, 2014 at 9:51 PM, Greg KH <greg@xxxxxxxxx> wrote: > > On Wed, Jul 16, 2014 at 08:57:38PM +0530, Chetan Nanda wrote: > > > > > > > > On Wed, Jul 16, 2014 at 8:49 PM, Chetan Nanda <chetannanda@xxxxxxxxx> > wrote: > > > > > > > > On Wed, Jul 16, 2014 at 6:39 PM, John de la Garza <john@xxxxxxxxx> > wrote: > > > > On Wed, Jul 16, 2014 at 04:00:18PM +0530, Chetan Nanda wrote: > > > A depends on B, so B is automatically loaded when A is loaded. > > > B module is also directly being used by the user side code via > misc > > > interface. > > >. > > > Now when I am unloading module A, via "modprobe -r A" it is > also > > unloading > > > the module B which is being used by the application and > resulting in > > the > > > kernel crash. > > > > You said that A depends on B, right? Why do you have A dependng > on B? > > If it A needs to have B then it makes sense that you can not > remove A > > while > > B is in use. If A doesn't need B, why not remove the dependency. > > > > > > A is calling few APIs defined by B. > > > > But why when user space application is already using module B. (it has > already > > open its device fd) kernel allows to remove it. > > > > I tried with doing try_module_get() in the module's open function, it > prevent > > module B unloading but cause thread doing modprobe -r to hang > > Is there any other way to mark module as busy when being used by user > > application? > > Never use try_module_get(), that is racy. > > What is the user/kernel interface you are using, and why doesn't it > automatically increase the module count when userspace opens the > interface? It should all be done in a way that your module doesn't need > to do anything special. > > > Hi Greg, > > Thanks for your mail. > > Module is using misc driver interface to export its functionality to > userspace, > > Need to debug further why module count is not getting incremented automatically > when module is open by userspace application via open system call. Are you properly setting the .owner field of your file operations structure to be THIS_MODULE? If not, try fixing that up. If you are, try posting your code for review. greg k-h _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
