On Thu, 22 Aug 2015 00:21:00 -0000, Valdis Kletnieks said: > Sounds like a reference counting problem. As far as I know, reference counter for line discipline sets to 0 in tty_register_ldisc(), increases to 1 in get_ldops() and decreases to 1 in put_ldops(). In tty_unregister_ldisc() it checks this value and if the reference counter > 0, it returns error -EBUSY And please advice how could I transfer data between kernel and user space not using filp_open() and filp_close(). 2015-08-22 0:21 GMT+03:00 <Valdis.Kletnieks@xxxxxx>: > On Thu, 13 Aug 2015 13:00:58 -0000, Margarita Glushkin said: >> I have a linux kernel driver for serial device, which uses line discipline >> and char device. Driver works with all old kernels, starting from 3.8 this >> driver still works, but when I unload it and load again to the memory >> (modprobe -r bpsctl_mod, after modprobe bpsctl_mod), it crashes the kernel. >> It can't unregister line discipline, because this line discipline is busy. > > Sounds like a reference counting problem. When your line discipline is busy, > somebody should have a reference on the module so it can't be unloaded. I don't > see any such reference taking/freeing in your posted code. > > Your crash is almost certainly because you're unloading it out from > under active use, which will probably result in somebody overlaying storage. > Frankly, you're probably lucky the system lives long enough for you to > reload it..... > > Oh, and filp_open() is usually the wrong way to solve whatever problem you > were trying to solve by using it. _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
