linux-kernel - Re: [PATCH 1/2] optee: fix tee out of memory failure seen during kexec reboot

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Date:   Wed, 24 Feb 2021 09:15:53 +0100
From:   Jens Wiklander <jens.wiklander@...aro.org>
To:     Allen Pais <apais@...ux.microsoft.com>
Cc:     Dhananjay Phadke <dphadke@...ux.microsoft.com>,
        allen.lkml@...il.com, zajec5@...il.com,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        op-tee@...ts.trustedfirmware.org,
        linux-arm-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH 1/2] optee: fix tee out of memory failure seen during
 kexec reboot

On Tue, Feb 23, 2021 at 09:56:13PM +0530, Allen Pais wrote:
> 
> 
> > > > > -	/*
> > > > > -	 * Ask OP-TEE to free all cached shared memory objects to decrease
> > > > > -	 * reference counters and also avoid wild pointers in secure world
> > > > > -	 * into the old shared memory range.
> > > > > -	 */
> > > > > -	optee_disable_shm_cache(optee);
> > > > > +	if (shutdown) {
> > > > > +		optee_disable_shm_cache(optee);
> > > > > +	} else {
> > > > > +		/*
> > > > > +		 * Ask OP-TEE to free all cached shared memory
> > > > > +		 * objects to decrease reference counters and
> > > > > +		 * also avoid wild pointers in secure world
> > > > > +		 * into the old shared memory range.
> > > > > +		 */
> > > > > +		optee_disable_shm_cache(optee);
> > > > Calling optee_disable_shm_cache() in both if and else. It could be
> > > > put in front of if().
> > > > 
> > > 
> > >    Ideally, I could just use optee_remove for shutdown() too.
> > > But it would not look good. Hence this approach.
> > 
> > What is the problem with using optee_remove() for shutdown()?
> > 
> 
>  There is no problem, I just thought it would be more cleaner/readable
> with this approach. If you'd like to keep it simple by just calling
> optee_remove() for shutdown() too, I could quickly send out V2.

In the patch you posted it looks like you'd like to call
only optee_disable_shm_cache() in the case of shutdown. Like:

static void optee_shutdown(struct platform_device *pdev)
{
        optee_disable_shm_cache(platform_get_drvdata(pdev));
}

and optee_remove() kept as it was before this patch.

Cheers,
Jens