linux-kernel - Re: [PATCH v6 2/7] crypto: caam - drop global context pointer and init

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Date:   Mon, 13 Jan 2020 09:41:47 +0000
From:   Horia Geanta <horia.geanta@....com>
To:     Andrey Smirnov <andrew.smirnov@...il.com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>
CC:     Chris Healy <cphealy@...il.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Iuliana Prodan <iuliana.prodan@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH v6 2/7] crypto: caam - drop global context pointer and
 init_done

On 1/8/2020 5:42 PM, Andrey Smirnov wrote:
> @@ -342,18 +324,16 @@ int caam_rng_init(struct device *ctrldev)
>  	if (!rng_inst)
>  		return 0;
>  
> -	rng_ctx = kmalloc(sizeof(*rng_ctx), GFP_DMA | GFP_KERNEL);
> -	if (!rng_ctx)
> +	ctx = devm_kzalloc(ctrldev, sizeof(*ctx), GFP_DMA | GFP_KERNEL);
> +	if (!ctx)
>  		return -ENOMEM;
>  
> -	dev_info(ctrldev, "registering rng-caam\n");
> +	ctx->rng.name    = "rng-caam";
> +	ctx->rng.init    = caam_init;
> +	ctx->rng.cleanup = caam_cleanup;
> +	ctx->rng.read    = caam_read;
>  
> -	err = hwrng_register(&caam_rng);
> -	if (!err) {
> -		init_done = true;
> -		return err;
> -	}
> +	dev_info(ctrldev, "registering rng-caam\n");
>  
> -	kfree(rng_ctx);
> -	return err;
> +	return devm_hwrng_register(ctrldev, &ctx->rng);
This means hwrng_unregister() is called only when ctrldev is removed.

OTOH caam_rng_init() could be called multiple times, e.g. if there's only one
jrdev left in the system and it's removed then added back.
This will lead to caam_rng_init() -> hwrng_register() called twice
with the same "rng-caam" name, without a hwrng_unregister() called in-between.

Horia