linux-kernel - Re: [PATCH] crypto: tcrypt: don't disable irqs and wait

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Date:   Wed, 26 Apr 2017 12:05:55 +0000
From:   Horia Geantă <horia.geanta@....com>
To:     Gilad Ben-Yossef <gilad@...yossef.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>
CC:     "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "gilad.benyossef@....com" <gilad.benyossef@....com>,
        Ofir Drang <ofir.drang@....com>
Subject: Re: [PATCH] crypto: tcrypt: don't disable irqs and wait

On 4/25/2017 11:25 AM, Gilad Ben-Yossef wrote:
> The tcrypt AEAD cycles speed tests disables irqs during the test, which is
> broken at the very least since commit
> '1425d2d17f7309c6 ("crypto: tcrypt - Fix AEAD speed tests")'
> adds a wait for completion as part of the test and probably since
> switching to the new AEAD API.
> 
> While the result of taking a cycle count diff may not mean much on SMP
> systems if the task migrates, it's good enough for tcrypt being the quick
> & dirty dev tool it is. It's also what all the other (i.e. hash) cycle
> speed tests do.
> 
> Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>
> Reported-by: Ofir Drang <ofir.drang@....com>
Reviewed-by: Horia Geantă <horia.geanta@....com>

I've also noticed this in CAAM accelerator - spin_unlock_bh() called
from caam_jr_enqueue() complains due to disabled interrupts:
WARNING: CPU: 4 PID: 2585 at kernel/softirq.c:161
.__local_bh_enable_ip+0x70/0xcc

Thanks,
Horia

> ---
>  crypto/tcrypt.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/crypto/tcrypt.c b/crypto/tcrypt.c
> index 9a11f3c..0dd6a43 100644
> --- a/crypto/tcrypt.c
> +++ b/crypto/tcrypt.c
> @@ -138,8 +138,6 @@ static int test_aead_cycles(struct aead_request *req, int enc, int blen)
>  	int ret = 0;
>  	int i;
>  
> -	local_irq_disable();
> -
>  	/* Warm-up run. */
>  	for (i = 0; i < 4; i++) {
>  		if (enc)
> @@ -169,8 +167,6 @@ static int test_aead_cycles(struct aead_request *req, int enc, int blen)
>  	}
>  
>  out:
> -	local_irq_enable();
> -
>  	if (ret == 0)
>  		printk("1 operation in %lu cycles (%d bytes)\n",
>  		       (cycles + 4) / 8, blen);
>