linux-kernel - Re: [PATCH] crypto: tegra - Remove an incorrect iommu_fwspec_free() call in tegra_se

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Date: Thu, 30 May 2024 12:30:48 +0200
From: "Thierry Reding" <thierry.reding@...il.com>
To: "Akhil R" <akhilrajeev@...dia.com>, "Christophe JAILLET"
 <christophe.jaillet@...adoo.fr>, "Herbert Xu"
 <herbert@...dor.apana.org.au>, "David S. Miller" <davem@...emloft.net>,
 "Jon Hunter" <jonathanh@...dia.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
 "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
 "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH] crypto: tegra - Remove an incorrect iommu_fwspec_free()
 call in tegra_se_remove()

On Wed May 29, 2024 at 8:53 AM CEST, Akhil R wrote:
> > The only iommu function call in this driver is a
> > tegra_dev_iommu_get_stream_id() which does not allocate anything and does
> > not take any reference.
> > 
> > More-over, what is freed is "se->dev" which has been devm_kzalloc()'ed in the
> > probe.
>
> I did not completely understand what is being tried to convey here.
> If I understand it right, iommu_fwspec_free() does not do anything
> with the "devm_kzalloc"ed variable. 
>
> It would probably be a good idea to remove this line from the commit message.

Yeah, I think that's a bit misleading. What iommu_fwspec_free() does is
get the iommu_fwspec from the passed-in device and then frees that
iommu_fwspec.

That said, as I was looking around I didn't spot anything that was
calling iommu_fwspec_free() in any of the cleanup paths, so either I'm
missing something or it's a real memory leak (though perhaps one that we
are ignoring on purpose because these are usually attached to devices
that don't just go away).

Thierry

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