From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Jeffrey Lien <Jeff.Lien@wdc.com>,
Christoph Hellwig <hch@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"herbert@gondor.apana.org.au" <herbert@gondor.apana.org.au>,
"tim.c.chen@linux.intel.com" <tim.c.chen@linux.intel.com>,
David Darrington <david.darrington@wdc.com>,
Jeff Furlong <jeff.furlong@wdc.com>
Subject: Re: [PATCH] Performance Improvement in CRC16 Calculations.
Date: Fri, 24 Aug 2018 22:54:26 +0100 [thread overview]
Message-ID: <CAKv+Gu8dMBUKmw+5rxWoiRKXngPeAsNyXzOY-nZwd3GPi1S5FA@mail.gmail.com> (raw)
In-Reply-To: <yq1tvnj780o.fsf@oracle.com>
On 24 August 2018 at 22:46, Martin K. Petersen
<martin.petersen@oracle.com> wrote:
>
> Ard,
>
>> I'd prefer to handle this without help from userland.
>>
>> It shouldn't be too difficult to register a module notifier that only
>> sets a flag (or the static key, even?), and to free and re-allocate
>> the crc_t10dif transform if the flag is set.
>
> Something like this proof of concept?
>
> diff --git a/lib/crc-t10dif.c b/lib/crc-t10dif.c
> index 1ad33e555805..87d0e8f0794a 100644
> --- a/lib/crc-t10dif.c
> +++ b/lib/crc-t10dif.c
> @@ -15,10 +15,50 @@
> #include <linux/init.h>
> #include <crypto/hash.h>
> #include <linux/static_key.h>
> +#include <linux/notifier.h>
>
> static struct crypto_shash *crct10dif_tfm;
> static struct static_key crct10dif_fallback __read_mostly;
>
> +static void crc_t10dif_print(void)
> +{
> + if (static_key_false(&crct10dif_fallback))
> + pr_info("CRC T10 DIF calculated using library function\n");
> + else
> + pr_info("CRC T10 DIF calculated using crypto hash %s\n",
> + crypto_tfm_alg_driver_name(crypto_shash_tfm(crct10dif_tfm)));
> +}
> +
> +static int crc_t10dif_rehash(struct notifier_block *self, unsigned long val, void *data)
> +{
> +#ifdef CONFIG_MODULES
> + struct module *mod = data;
> +
> + if (val != MODULE_STATE_LIVE ||
> + strncmp(mod->name, "crct10dif", strlen("crct10dif")))
> + return 0;
> +
> + /* Fall back to library function while we replace the tfm */
> + static_key_slow_inc(&crct10dif_fallback);
> +
> + crypto_free_shash(crct10dif_tfm);
> + crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
> + if (IS_ERR(crct10dif_tfm)) {
> + crct10dif_tfm = NULL;
> + goto out;
> + }
> +
> + static_key_slow_dec(&crct10dif_fallback);
> +out:
> + crc_t10dif_print();
> + return 0;
> +#endif /* CONFIG_MODULES */
> +}
> +
> +static struct notifier_block crc_t10dif_nb = {
> + .notifier_call = crc_t10dif_rehash,
> +};
> +
> __u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
> {
> struct {
> @@ -49,16 +90,21 @@ EXPORT_SYMBOL(crc_t10dif);
>
> static int __init crc_t10dif_mod_init(void)
> {
> + register_module_notifier(&crc_t10dif_nb);
> +
> crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
> if (IS_ERR(crct10dif_tfm)) {
> static_key_slow_inc(&crct10dif_fallback);
> crct10dif_tfm = NULL;
> }
> +
> + crc_t10dif_print();
> return 0;
> }
>
> static void __exit crc_t10dif_mod_fini(void)
> {
> + unregister_module_notifier(&crc_t10dif_nb);
> crypto_free_shash(crct10dif_tfm);
> }
>
This looks like it should work, yes. It does rely on the module name
to start with 'crct10dif' but I guess that is reasonable, and matches
the current state on all architectures.
Anyone care to boot test this? Jeffrey?
next prev parent reply other threads:[~2018-08-24 21:54 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-10 19:12 [PATCH] Performance Improvement in CRC16 Calculations Jeff Lien
2018-08-10 19:23 ` Joe Perches
2018-08-10 20:02 ` Nicolas Pitre
2018-08-11 0:11 ` Joe Perches
2018-08-11 0:34 ` Nicolas Pitre
2018-08-11 2:39 ` Douglas Gilbert
2018-08-11 9:04 ` Joe Perches
2018-08-11 15:06 ` Joe Perches
2018-08-13 18:41 ` Jeffrey Lien
2018-08-13 3:36 ` Douglas Gilbert
2018-08-13 4:29 ` Joe Perches
2018-08-10 20:00 ` Nicolas Pitre
2018-08-10 20:16 ` Eric Biggers
2018-08-16 14:02 ` Jeffrey Lien
2018-08-16 14:22 ` Douglas Gilbert
2018-08-16 15:41 ` Christophe LEROY
2018-08-16 17:38 ` Douglas Gilbert
2018-08-17 3:20 ` Martin K. Petersen
2018-08-16 15:47 ` Christophe LEROY
2018-08-10 20:56 ` Douglas Gilbert
2018-08-11 15:36 ` Martin K. Petersen
2018-08-11 16:35 ` Joe Perches
2018-08-22 1:40 ` Martin K. Petersen
2018-08-22 6:20 ` Christoph Hellwig
2018-08-24 15:32 ` Jeffrey Lien
2018-08-24 15:39 ` Ard Biesheuvel
2018-08-24 16:29 ` Martin K. Petersen
2018-08-24 17:38 ` Ard Biesheuvel
2018-08-24 21:46 ` Martin K. Petersen
2018-08-24 21:54 ` Ard Biesheuvel [this message]
2018-08-24 22:12 ` Martin K. Petersen
2018-08-25 6:12 ` Herbert Xu
2018-08-26 2:35 ` Martin K. Petersen
2018-08-26 2:40 ` [PATCH 1/4] crypto: Introduce notifier for new crypto algorithms Martin K. Petersen
2018-08-26 2:40 ` [PATCH 2/4] crc-t10dif: Pick better transform if one becomes available Martin K. Petersen
2018-08-27 6:13 ` Herbert Xu
2018-08-26 2:40 ` [PATCH 3/4] crc-t10dif: Allow current transform to be inspected in sysfs Martin K. Petersen
2018-08-26 2:40 ` [PATCH 4/4] block: Integrity profile init function to trigger module loads Martin K. Petersen
2018-08-26 8:22 ` Ard Biesheuvel
2018-08-26 13:30 ` Martin K. Petersen
2018-08-26 13:44 ` Ard Biesheuvel
2018-08-26 13:48 ` Martin K. Petersen
2018-08-27 6:09 ` [PATCH 1/4] crypto: Introduce notifier for new crypto algorithms Herbert Xu
2018-08-30 14:57 ` Martin K. Petersen
2018-08-30 15:00 ` [PATCH v2 1/3] " Martin K. Petersen
2018-08-30 15:00 ` [PATCH v2 2/3] crc-t10dif: Pick better transform if one becomes available Martin K. Petersen
2018-08-30 15:00 ` [PATCH v2 3/3] crc-t10dif: Allow current transform to be inspected in sysfs Martin K. Petersen
2018-08-31 17:17 ` [PATCH v2 1/3] crypto: Introduce notifier for new crypto algorithms Jeffrey Lien
2018-09-04 5:21 ` Herbert Xu
2018-09-04 13:30 ` Torsten Duwe
2018-08-24 16:30 ` [PATCH] Performance Improvement in CRC16 Calculations Martin K. Petersen
2018-08-13 4:44 ` Chaitanya Kulkarni
2018-08-13 11:45 ` David Laight
2018-08-13 13:50 ` David Laight
2018-08-13 22:44 ` Tim Chen
2018-08-15 12:51 ` Jeffrey Lien
2018-08-15 18:31 ` Pavel Machek
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