linux-kernel - Re: [PATCH v1 00/17] tee: Use bus callbacks instead of driver callbacks

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Message-ID: <max5wxkcjjvnftwfwgymybwbnvf5s3ytwpy4oo5i74kfvnav4m@m2wasqyxsf4h>
Date: Wed, 17 Dec 2025 09:21:41 +0100
From: Uwe Kleine-König <u.kleine-koenig@...libre.com>
To: Sumit Garg <sumit.garg@...nel.org>
Cc: Sumit Garg <sumit.garg@....qualcomm.com>, 
	Jens Wiklander <jens.wiklander@...aro.org>, Olivia Mackall <olivia@...enic.com>, 
	Herbert Xu <herbert@...dor.apana.org.au>, Clément Léger <clement.leger@...tlin.com>, 
	Alexandre Belloni <alexandre.belloni@...tlin.com>, Ard Biesheuvel <ardb@...nel.org>, 
	Maxime Coquelin <mcoquelin.stm32@...il.com>, Alexandre Torgue <alexandre.torgue@...s.st.com>, 
	Ilias Apalodimas <ilias.apalodimas@...aro.org>, Jan Kiszka <jan.kiszka@...mens.com>, 
	Sudeep Holla <sudeep.holla@....com>, Christophe JAILLET <christophe.jaillet@...adoo.fr>, 
	Michael Chan <michael.chan@...adcom.com>, Pavan Chebbi <pavan.chebbi@...adcom.com>, 
	Rafał Miłecki <zajec5@...il.com>, James Bottomley <James.Bottomley@...senpartnership.com>, 
	Jarkko Sakkinen <jarkko@...nel.org>, Mimi Zohar <zohar@...ux.ibm.com>, 
	David Howells <dhowells@...hat.com>, Paul Moore <paul@...l-moore.com>, 
	James Morris <jmorris@...ei.org>, "Serge E. Hallyn" <serge@...lyn.com>, 
	Peter Huewe <peterhuewe@....de>, op-tee@...ts.trustedfirmware.org, linux-kernel@...r.kernel.org, 
	linux-crypto@...r.kernel.org, linux-rtc@...r.kernel.org, linux-efi@...r.kernel.org, 
	linux-stm32@...md-mailman.stormreply.com, linux-arm-kernel@...ts.infradead.org, 
	Cristian Marussi <cristian.marussi@....com>, arm-scmi@...r.kernel.org, netdev@...r.kernel.org, 
	linux-mips@...r.kernel.org, linux-integrity@...r.kernel.org, keyrings@...r.kernel.org, 
	linux-security-module@...r.kernel.org, Jason Gunthorpe <jgg@...pe.ca>
Subject: Re: [PATCH v1 00/17] tee: Use bus callbacks instead of driver
 callbacks

Hello Sumit,

On Wed, Dec 17, 2025 at 01:25:39PM +0530, Sumit Garg wrote:
> On Tue, Dec 16, 2025 at 12:08:38PM +0100, Uwe Kleine-König wrote:
> > On Tue, Dec 16, 2025 at 01:08:38PM +0530, Sumit Garg wrote:
> > > On Mon, Dec 15, 2025 at 3:02 PM Uwe Kleine-König
> > > <u.kleine-koenig@...libre.com> wrote:
> > > >  - Why does optee_probe() in drivers/tee/optee/smc_abi.c unregister all
> > > >    optee devices in its error path (optee_unregister_devices())?
> > > 
> > > This is mostly to take care of if any device got registered before the
> > > failure occured. Let me know if you have a better way to address that.
> > 
> > Without understanding the tee stuff, I'd say: Don't bother and only undo
> > the things that probe did before the failure.
> 
> True, but this is special case where if there is any leftover device
> registered from the TEE implementation then it is likely going to cause
> the corresponding kernel client driver crash.

You are aware that this is racy? So if a driver crashes e.g. after
teedev_close_context() it might happen that it is registered just after
optee_unregister_devices() returns.

Best regards
Uwe

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