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

From: Marion & Christophe JAILLET
Date: Fri May 31 2024 - 16:14:04 EST



Le 31/05/2024 à 07:36, Akhil R a écrit :
-----Original Message-----
From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Sent: Friday, May 31, 2024 10:53 AM
To: Akhil R <akhilrajeev@xxxxxxxxxx>
Cc: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>; David S. Miller
<davem@xxxxxxxxxxxxx>; Thierry Reding <thierry.reding@xxxxxxxxx>; Jon
Hunter <jonathanh@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; kernel-
janitors@xxxxxxxxxxxxxxx; linux-crypto@xxxxxxxxxxxxxxx; linux-
tegra@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] crypto: tegra - Remove an incorrect iommu_fwspec_free()
call in tegra_se_remove()

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On Wed, May 29, 2024 at 06:53:42AM +0000, 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.
I think he means that as the memory was allocated via devm, it will
be automatically freed by the kernel and the driver does not need
to (and should not) free the memory by hand.


Yes, that is my point.

Ya. But iommu_fwspec_free() does not free the memory allocated via devm.

I think iommu_fwspec_free() is expected to be called in symmetry with
iommu_fwspec_init(). So, I do agree that the SE driver does not allocate
what is freed by iommu_fwspec_free(), but I feel this line is a bit misleading.

Yes, I spoke too fast.
What is freed is dev_iommu_fwspec_get(dev);, not dev. So the sentence I wrote makes no sense and should be removed :(


CJ