On Fri, Jan 13, 2017 at 04:42:30PM -0800, Andrey Pronin wrote: > On Fri, Jan 13, 2017 at 05:28:57PM -0700, Jason Gunthorpe wrote: > > On Fri, Jan 13, 2017 at 04:09:54PM -0800, Andrey Pronin wrote: > > > Resetting TPM while processing a command may lead to issues > > > on the next boot. Ensure that we don't have any ongoing > > > commands, and that no further commands can be sent to the chip > > > by unregistering the device in the shutdown handler. > > > tpm_chip_unregister() waits for the completion of an ongoing > > > command, if any, and then clears out chip->ops and unregisters > > > sysfs entities. > > > > Unregistering in a shutdown handler seems very strange, it also waits > > for userspace things, so I wonder if it could be problematic? > > > > Maybe just use > > > > down_write(&chip->ops_sem); > > chip->ops = NULL; > > up_write(&chip->ops_sem); > > > > In the shutdown handler? > > down_write(&chip->ops_sem) would still wait for completing the initiated > writes, since tpm_write() in tpm-dev.c calls tpm_try_get_ops(). > Also, tpm-sysfs.c calls chip->ops directly, so sysfs should be > unregistered first.
Why don't you fix the tpm-sysfs issue but rather misusing tpm_chip_unregister? /Jarkko
