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Message-ID: <58A45E4A.8080508@caviumnetworks.com>
Date: Wed, 15 Feb 2017 19:27:30 +0530
From: Narayana Prasad Athreya <pathreya@...iumnetworks.com>
To: Seth Jennings <sjenning@...hat.com>,
Mahipal Challa <mahipalreddy2006@...il.com>
Cc: herbert@...dor.apana.org.au, davem@...emloft.net,
linux-crypto@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
Linux-MM <linux-mm@...ck.org>, pathreya@...ium.com,
vnair@...ium.com, Mahipal Challa <Mahipal.Challa@...ium.com>,
Vishnu Nair <Vishnu.Nair@...ium.com>
Subject: Re: [RFC PATCH v1 1/1] mm: zswap - Add crypto acomp/scomp framework
support
> I assume all of these crypto_acomp_[compress|decompress] calls are
> actually synchronous,
> not asynchronous as the name suggests. Otherwise, this would blow up
> quite spectacularly
> since all the resources we use in the call get derefed/unmapped below.
>
> Could an async algorithm be implement/used that would break this assumption?
The callback is set to NULL using acomp_request_set_callback(). This
implies synchronous mode of operation. So the underlying implementation
must complete the operation synchronously.
Prasad
On Tuesday 14 February 2017 09:50 PM, Seth Jennings wrote:
> On Tue, Feb 14, 2017 at 9:40 AM, Mahipal Challa
> <mahipalreddy2006@...il.com> wrote:
>> This adds the support for kernel's crypto new acomp/scomp framework
>> to zswap.
>>
>> Signed-off-by: Mahipal Challa <Mahipal.Challa@...ium.com>
>> Signed-off-by: Vishnu Nair <Vishnu.Nair@...ium.com>
>> ---
>> mm/zswap.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++--------------
>> 1 file changed, 99 insertions(+), 30 deletions(-)
>>
>> diff --git a/mm/zswap.c b/mm/zswap.c
>> index 067a0d6..d08631b 100644
>> --- a/mm/zswap.c
>> +++ b/mm/zswap.c
>> @@ -33,6 +33,8 @@
>> #include <linux/rbtree.h>
>> #include <linux/swap.h>
>> #include <linux/crypto.h>
>> +#include <crypto/acompress.h>
>> +#include <linux/scatterlist.h>
>> #include <linux/mempool.h>
>> #include <linux/zpool.h>
>>
>> @@ -114,7 +116,8 @@ static int zswap_compressor_param_set(const char *,
>>
>> struct zswap_pool {
>> struct zpool *zpool;
>> - struct crypto_comp * __percpu *tfm;
>> + struct crypto_acomp * __percpu *acomp;
>> + struct acomp_req * __percpu *acomp_req;
>> struct kref kref;
>> struct list_head list;
>> struct work_struct work;
>> @@ -379,30 +382,49 @@ static int zswap_dstmem_dead(unsigned int cpu)
>> static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
>> {
>> struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
>> - struct crypto_comp *tfm;
>> + struct crypto_acomp *acomp;
>> + struct acomp_req *acomp_req;
>>
>> - if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
>> + if (WARN_ON(*per_cpu_ptr(pool->acomp, cpu)))
>> return 0;
>> + if (WARN_ON(*per_cpu_ptr(pool->acomp_req, cpu)))
>> + return 0;
>> +
>> + acomp = crypto_alloc_acomp(pool->tfm_name, 0, 0);
>> + if (IS_ERR_OR_NULL(acomp)) {
>> + pr_err("could not alloc crypto acomp %s : %ld\n",
>> + pool->tfm_name, PTR_ERR(acomp));
>> + return -ENOMEM;
>> + }
>> + *per_cpu_ptr(pool->acomp, cpu) = acomp;
>>
>> - tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
>> - if (IS_ERR_OR_NULL(tfm)) {
>> - pr_err("could not alloc crypto comp %s : %ld\n",
>> - pool->tfm_name, PTR_ERR(tfm));
>> + acomp_req = acomp_request_alloc(acomp);
>> + if (IS_ERR_OR_NULL(acomp_req)) {
>> + pr_err("could not alloc crypto acomp %s : %ld\n",
>> + pool->tfm_name, PTR_ERR(acomp));
>> return -ENOMEM;
>> }
>> - *per_cpu_ptr(pool->tfm, cpu) = tfm;
>> + *per_cpu_ptr(pool->acomp_req, cpu) = acomp_req;
>> +
>> return 0;
>> }
>>
>> static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
>> {
>> struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
>> - struct crypto_comp *tfm;
>> + struct crypto_acomp *acomp;
>> + struct acomp_req *acomp_req;
>> +
>> + acomp_req = *per_cpu_ptr(pool->acomp_req, cpu);
>> + if (!IS_ERR_OR_NULL(acomp_req))
>> + acomp_request_free(acomp_req);
>> + *per_cpu_ptr(pool->acomp_req, cpu) = NULL;
>> +
>> + acomp = *per_cpu_ptr(pool->acomp, cpu);
>> + if (!IS_ERR_OR_NULL(acomp))
>> + crypto_free_acomp(acomp);
>> + *per_cpu_ptr(pool->acomp, cpu) = NULL;
>>
>> - tfm = *per_cpu_ptr(pool->tfm, cpu);
>> - if (!IS_ERR_OR_NULL(tfm))
>> - crypto_free_comp(tfm);
>> - *per_cpu_ptr(pool->tfm, cpu) = NULL;
>> return 0;
>> }
>>
>> @@ -503,8 +525,14 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
>> pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));
>>
>> strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
>> - pool->tfm = alloc_percpu(struct crypto_comp *);
>> - if (!pool->tfm) {
>> + pool->acomp = alloc_percpu(struct crypto_acomp *);
>> + if (!pool->acomp) {
>> + pr_err("percpu alloc failed\n");
>> + goto error;
>> + }
>> +
>> + pool->acomp_req = alloc_percpu(struct acomp_req *);
>> + if (!pool->acomp_req) {
>> pr_err("percpu alloc failed\n");
>> goto error;
>> }
>> @@ -526,7 +554,8 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
>> return pool;
>>
>> error:
>> - free_percpu(pool->tfm);
>> + free_percpu(pool->acomp_req);
>> + free_percpu(pool->acomp);
>> if (pool->zpool)
>> zpool_destroy_pool(pool->zpool);
>> kfree(pool);
>> @@ -566,7 +595,8 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
>> zswap_pool_debug("destroying", pool);
>>
>> cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
>> - free_percpu(pool->tfm);
>> + free_percpu(pool->acomp_req);
>> + free_percpu(pool->acomp);
>> zpool_destroy_pool(pool->zpool);
>> kfree(pool);
>> }
>> @@ -763,7 +793,8 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
>> pgoff_t offset;
>> struct zswap_entry *entry;
>> struct page *page;
>> - struct crypto_comp *tfm;
>> + struct scatterlist input, output;
>> + struct acomp_req *req;
>> u8 *src, *dst;
>> unsigned int dlen;
>> int ret;
>> @@ -803,14 +834,23 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
>>
>> case ZSWAP_SWAPCACHE_NEW: /* page is locked */
>> /* decompress */
>> + req = *get_cpu_ptr(entry->pool->acomp_req);
>> dlen = PAGE_SIZE;
>> src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
>> ZPOOL_MM_RO) + sizeof(struct zswap_header);
>> dst = kmap_atomic(page);
>> - tfm = *get_cpu_ptr(entry->pool->tfm);
>> - ret = crypto_comp_decompress(tfm, src, entry->length,
>> - dst, &dlen);
>> - put_cpu_ptr(entry->pool->tfm);
>> +
>> + sg_init_one(&input, src, entry->length);
>> + sg_init_one(&output, dst, dlen);
>> + acomp_request_set_params(req, &input, &output, entry->length,
>> + dlen);
>> + acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
>> + NULL, NULL);
>> +
>> + ret = crypto_acomp_decompress(req);
> I assume all of these crypto_acomp_[compress|decompress] calls are
> actually synchronous,
> not asynchronous as the name suggests. Otherwise, this would blow up
> quite spectacularly
> since all the resources we use in the call get derefed/unmapped below.
>
> Could an async algorithm be implement/used that would break this assumption?
>
> Seth
>
>> +
>> + dlen = req->dlen;
>> + put_cpu_ptr(entry->pool->acomp_req);
>> kunmap_atomic(dst);
>> zpool_unmap_handle(entry->pool->zpool, entry->handle);
>> BUG_ON(ret);
>> @@ -886,7 +926,8 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
>> {
>> struct zswap_tree *tree = zswap_trees[type];
>> struct zswap_entry *entry, *dupentry;
>> - struct crypto_comp *tfm;
>> + struct scatterlist input, output;
>> + struct acomp_req *req;
>> int ret;
>> unsigned int dlen = PAGE_SIZE, len;
>> unsigned long handle;
>> @@ -925,12 +966,27 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
>> }
>>
>> /* compress */
>> + req = *get_cpu_ptr(entry->pool->acomp_req);
>> + if (!req) {
>> + put_cpu_ptr(entry->pool->acomp_req);
>> + ret = -EINVAL;
>> + goto freepage;
>> + }
>> +
>> dst = get_cpu_var(zswap_dstmem);
>> - tfm = *get_cpu_ptr(entry->pool->tfm);
>> src = kmap_atomic(page);
>> - ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
>> +
>> + sg_init_one(&input, src, PAGE_SIZE);
>> + /* zswap_dstmem is of size (PAGE_SIZE * 2). Reflect same in sg_list */
>> + sg_init_one(&output, dst, PAGE_SIZE * 2);
>> + acomp_request_set_params(req, &input, &output, PAGE_SIZE, dlen);
>> + acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, NULL,
>> + NULL);
>> +
>> + ret = crypto_acomp_compress(req);
>> kunmap_atomic(src);
>> - put_cpu_ptr(entry->pool->tfm);
>> + put_cpu_ptr(entry->pool->acomp_req);
>> + dlen = req->dlen;
>> if (ret) {
>> ret = -EINVAL;
>> goto put_dstmem;
>> @@ -998,7 +1054,8 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
>> {
>> struct zswap_tree *tree = zswap_trees[type];
>> struct zswap_entry *entry;
>> - struct crypto_comp *tfm;
>> + struct scatterlist input, output;
>> + struct acomp_req *req;
>> u8 *src, *dst;
>> unsigned int dlen;
>> int ret;
>> @@ -1014,13 +1071,25 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
>> spin_unlock(&tree->lock);
>>
>> /* decompress */
>> + req = *get_cpu_ptr(entry->pool->acomp_req);
>> + if (!req) {
>> + put_cpu_ptr(entry->pool->acomp_req);
>> + return -1;
>> + }
>> dlen = PAGE_SIZE;
>> src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
>> ZPOOL_MM_RO) + sizeof(struct zswap_header);
>> dst = kmap_atomic(page);
>> - tfm = *get_cpu_ptr(entry->pool->tfm);
>> - ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen);
>> - put_cpu_ptr(entry->pool->tfm);
>> +
>> + sg_init_one(&input, src, entry->length);
>> + sg_init_one(&output, dst, dlen);
>> + acomp_request_set_params(req, &input, &output, entry->length, dlen);
>> + acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, NULL,
>> + NULL);
>> +
>> + ret = crypto_acomp_decompress(req);
>> +
>> + put_cpu_ptr(entry->pool->acomp_req);
>> kunmap_atomic(dst);
>> zpool_unmap_handle(entry->pool->zpool, entry->handle);
>> BUG_ON(ret);
>> --
>> 1.8.3.1
>>
> .
>
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