Re: [PATCH backportt 5.16] optee: use driver internal tee_context for some rpc

[Greg KH <greg@kroah.com>]

On Fri, Feb 18, 2022 at 11:45:29AM +0100, Jens Wiklander wrote:
> commit aceeafefff736057e8f93f19bbfbef26abd94604 upstream
> 
> Adds a driver private tee_context to struct optee.
> 
> The new driver internal tee_context is used when allocating driver
> private shared memory. This decouples the shared memory object from its
> original tee_context. This is needed when the life time of such a memory
> allocation outlives the client tee_context.
> 
> This patch fixes the problem described below:
> 
> The addition of a shutdown hook by commit f25889f93184 ("optee: fix tee out
> of memory failure seen during kexec reboot") introduced a kernel shutdown
> regression that can be triggered after running the OP-TEE xtest suites.
> 
> Once the shutdown hook is called it is not possible to communicate any more
> with the supplicant process because the system is not scheduling task any
> longer. Thus if the optee driver shutdown path receives a supplicant RPC
> request from the OP-TEE we will deadlock the kernel's shutdown.
> 
> Fixes: f25889f93184 ("optee: fix tee out of memory failure seen during kexec reboot")
> Fixes: 217e0250cccb ("tee: use reference counting for tee_context")
> Reported-by: Lars Persson <larper@axis.com>
> Cc: stable@vger.kernel.org # 1e2c3ef0496e tee: export teedev_open() and teedev_close_context()
> Cc: stable@vger.kernel.org
> Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
> [JW: backport to 5.16-stable + update commit message]

This and 5.15 backport now queued up.

This needs to go farther back as well, right?

thanks

greg k-h