linux-kernel - Re: [REPORT] Possible unnecessary usages of GFP

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Date:   Mon, 23 Jul 2018 14:21:01 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [REPORT] Possible unnecessary usages of GFP_ATOMIC in
 crypto/ablkcipher.c

On Mon, Jul 23, 2018 at 10:39:40AM +0800, Jia-Ju Bai wrote:
> My tool DCNS reports three unnecessary usages of GFP_ATOMIC in
> crypto/ablkcipher.c:
> crypto/ablkcipher.c, 162: kmalloc(GFP_ATOMIC) in ablkcipher_next_slow
> crypto/ablkcipher.c, 199: kmalloc(GFP_ATOMIC) in ablkcipher_copy_iv
> crypto/ablkcipher.c, 315: kmalloc(GFP_ATOMIC) in setkey_unaligned
> 
> I meant to manually check the code, but I find that there are many functions
> calling ablkcipher_next_slow(),
> ablkcipher_copy_iv() and setkey_unaligned(), so I am not sure whether the
> above three reports are true.
> 
> Could someone help me to validate these reports?
> Thanks a lot in advance :)

They must use GFP_ATOMIC because they can be called from softirq
context, e.g., IPsec.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt