On Fri, Jul 10, 2020 at 11:25:44AM -0700, Andrey Pronin wrote: > > Why does not tpm_del_char_device need this? > > "Not" is a typo in the sentence above, right? tpm_del_char_device *does* > need the fix. When tpm_class_shutdown is called it sets chip->ops to > NULL. If tpm_del_char_device is called after that, it doesn't check if > chip->ops is NULL (normal kernel API and char device API calls go > through tpm_try_get_ops, but tpm_del_char_device doesn't) and proceeds to > call tpm2_shutdown(), which tries sending the command and dereferences > chip->ops. It's a typo, yes. Sorry about that. tpm_class_shutdown() is essentially tail of tpm_del_char_device(). To clean things up, I'd suggest dropping tpm_del_char_device() and call tpm_class_shutdown() in tpm_chip_unregisters() along, and open coding things that prepend it in tpm_del_char_device(). /Jarkko
