linux-kernel - Re: [PATCH v5 2/4] crypto: ti - Add support for AES-CTR in DTHEv2 driver

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Message-ID: <afabae10-95fa-43c2-8929-c6d8164a56f2@ti.com>
Date: Thu, 6 Nov 2025 13:55:40 +0530
From: T Pratham <t-pratham@...com>
To: Herbert Xu <herbert@...dor.apana.org.au>
CC: "David S. Miller" <davem@...emloft.net>, Manorit Chawdhry
	<m-chawdhry@...com>, Kamlesh Gurudasani <kamlesh@...com>, Shiva Tripathi
	<s-tripathi1@...com>, Kavitha Malarvizhi <k-malarvizhi@...com>, "Vishal
 Mahaveer" <vishalm@...com>, Praneeth Bajjuri <praneeth@...com>,
	<linux-crypto@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 2/4] crypto: ti - Add support for AES-CTR in DTHEv2
 driver

On 06/11/25 12:53, Herbert Xu wrote:
> On Fri, Oct 31, 2025 at 08:11:34PM +0530, T Pratham wrote:
>>
>> Let me know if this is fine.
> 
> Yes I think this should work.
> 
>> However, I suppose we similarly cannot do allocations in AEADs as well?
>> If that is the case, my current code relies a lot on it (using sg_split
>> to separate AAD from {plain, cipher}text and applying padding like CTR
>> here, both of which allocate memory).
>>
>> I can change padding to avoid kmallocs like CTR easily. But separating
>> AAD and plaintext/ciphertext without using sg_split will be a task. Let
>> me know if this is correct, so that I'll split the series and send
>> ciphers now, and AEADs later.
> 
> OK it's not totally forbidden to allocate memory.  However, you
> should only use GFP_ATOMIC to avoid dead-lock (GFP_KERNEL can
> trigger writes to storage, which can in turn call crypto), and
> provide a fallback path to software crypto when the allocation
> fails.
> 
> Cheers,

Understood. Thanks for the insights. I'll re-spin the series with
necessary changes.

-- 
Regards
T Pratham <t-pratham@...com>