netdev - Using the aesni generic gcm(aes) aead in atomic context

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Date:   Mon, 30 Oct 2017 15:18:21 +0000
From:   Ilya Lesokhin <ilyal@...lanox.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "sd@...asysnail.net" <sd@...asysnail.net>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>
CC:     Boris Pismenny <borisp@...lanox.com>
Subject: Using the aesni generic gcm(aes) aead in atomic context

Hi,
I've tried using the aesni generic gcm(aes) aead to implement TLS SW fallback and
I'm getting 
[ 3356.839506] BUG: sleeping function called from invalid context at ./include/crypto/algapi.h:417

The warning is coming from a ___might_sleep() macro that is called if CRYPTO_TFM_REQ_MAY_SLEEP is set.
I'm getting the warning regardless of if pass CRYPTO_ALG_ASYNC or 0 as flags to crypto_alloc_aead("gcm(aes)", 0, flags).

I've also noticed that rfc4106_encrypt() includes a irq_fpu_usable() check while generic_gcmaes_encrypt() doesn't. 
Is the generic gcm(aes) aead unsafe in atomic context?
And if so which aead should I use?

Finally, out of curiosity, doesn't macsec crypto run in atomic context?

Thanks,
Ilya