nvmet-tcp: switch to using the crc32c library

Now that the crc32c() library function directly takes advantage of
architecture-specific optimizations, it is unnecessary to go through the
crypto API.  Just use crc32c().  This is much simpler, and it improves
performance due to eliminating the crypto API overhead.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Author: ebiggers

drivers/nvme/target/tcp.c

@@ -7,6 +7,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
+#include <linux/crc32c.h>
 #include <linux/err.h>
 #include <linux/nvme-tcp.h>
 #include <linux/nvme-keyring.h>
@@ -17,7 +18,6 @@
 #include <net/handshake.h>
 #include <linux/inet.h>
 #include <linux/llist.h>
-#include <crypto/hash.h>
 #include <trace/events/sock.h>
 
 #include "nvmet.h"
@@ -172,8 +172,6 @@ struct nvmet_tcp_queue {
 	/* digest state */
 	bool			hdr_digest;
 	bool			data_digest;
-	struct ahash_request	*snd_hash;
-	struct ahash_request	*rcv_hash;
 
 	/* TLS state */
 	key_serial_t		tls_pskid;
@@ -294,14 +292,9 @@ static inline u8 nvmet_tcp_ddgst_len(struct nvmet_tcp_queue *queue)
 	return queue->data_digest ? NVME_TCP_DIGEST_LENGTH : 0;
 }
 
-static inline void nvmet_tcp_hdgst(struct ahash_request *hash,
-		void *pdu, size_t len)
+static inline void nvmet_tcp_hdgst(void *pdu, size_t len)
 {
-	struct scatterlist sg;
-
-	sg_init_one(&sg, pdu, len);
-	ahash_request_set_crypt(hash, &sg, pdu + len, len);
-	crypto_ahash_digest(hash);
+	put_unaligned_le32(~crc32c(~0, pdu, len), pdu + len);
 }
 
 static int nvmet_tcp_verify_hdgst(struct nvmet_tcp_queue *queue,
@@ -318,7 +311,7 @@ static int nvmet_tcp_verify_hdgst(struct nvmet_tcp_queue *queue,
 	}
 
 	recv_digest = *(__le32 *)(pdu + hdr->hlen);
-	nvmet_tcp_hdgst(queue->rcv_hash, pdu, len);
+	nvmet_tcp_hdgst(pdu, len);
 	exp_digest = *(__le32 *)(pdu + hdr->hlen);
 	if (recv_digest != exp_digest) {
 		pr_err("queue %d: header digest error: recv %#x expected %#x\n",
@@ -441,12 +434,24 @@ static int nvmet_tcp_map_data(struct nvmet_tcp_cmd *cmd)
 	return NVME_SC_INTERNAL;
 }
 
-static void nvmet_tcp_calc_ddgst(struct ahash_request *hash,
-		struct nvmet_tcp_cmd *cmd)
+static void nvmet_tcp_calc_ddgst(struct nvmet_tcp_cmd *cmd)
 {
-	ahash_request_set_crypt(hash, cmd->req.sg,
-		(void *)&cmd->exp_ddgst, cmd->req.transfer_len);
-	crypto_ahash_digest(hash);
+	size_t total_len = cmd->req.transfer_len;
+	struct scatterlist *sg = cmd->req.sg;
+	u32 crc = ~0;
+
+	while (total_len) {
+		size_t len = min_t(size_t, total_len, sg->length);
+
+		/*
+		 * Note that the scatterlist does not contain any highmem pages,
+		 * as it was allocated by sgl_alloc() with GFP_KERNEL.
+		 */
+		crc = crc32c(crc, sg_virt(sg), len);
+		total_len -= len;
+		sg = sg_next(sg);
+	}
+	cmd->exp_ddgst = cpu_to_le32(~crc);
 }
 
 static void nvmet_setup_c2h_data_pdu(struct nvmet_tcp_cmd *cmd)
@@ -473,19 +478,18 @@ static void nvmet_setup_c2h_data_pdu(struct nvmet_tcp_cmd *cmd)
 
 	if (queue->data_digest) {
 		pdu->hdr.flags |= NVME_TCP_F_DDGST;
-		nvmet_tcp_calc_ddgst(queue->snd_hash, cmd);
+		nvmet_tcp_calc_ddgst(cmd);
 	}
 
 	if (cmd->queue->hdr_digest) {
 		pdu->hdr.flags |= NVME_TCP_F_HDGST;
-		nvmet_tcp_hdgst(queue->snd_hash, pdu, sizeof(*pdu));
+		nvmet_tcp_hdgst(pdu, sizeof(*pdu));
 	}
 }
 
 static void nvmet_setup_r2t_pdu(struct nvmet_tcp_cmd *cmd)
 {
 	struct nvme_tcp_r2t_pdu *pdu = cmd->r2t_pdu;
-	struct nvmet_tcp_queue *queue = cmd->queue;
 	u8 hdgst = nvmet_tcp_hdgst_len(cmd->queue);
 
 	cmd->offset = 0;
@@ -503,14 +507,13 @@ static void nvmet_setup_r2t_pdu(struct nvmet_tcp_cmd *cmd)
 	pdu->r2t_offset = cpu_to_le32(cmd->rbytes_done);
 	if (cmd->queue->hdr_digest) {
 		pdu->hdr.flags |= NVME_TCP_F_HDGST;
-		nvmet_tcp_hdgst(queue->snd_hash, pdu, sizeof(*pdu));
+		nvmet_tcp_hdgst(pdu, sizeof(*pdu));
 	}
 }
 
 static void nvmet_setup_response_pdu(struct nvmet_tcp_cmd *cmd)
 {
 	struct nvme_tcp_rsp_pdu *pdu = cmd->rsp_pdu;
-	struct nvmet_tcp_queue *queue = cmd->queue;
 	u8 hdgst = nvmet_tcp_hdgst_len(cmd->queue);
 
 	cmd->offset = 0;
@@ -523,7 +526,7 @@ static void nvmet_setup_response_pdu(struct nvmet_tcp_cmd *cmd)
 	pdu->hdr.plen = cpu_to_le32(pdu->hdr.hlen + hdgst);
 	if (cmd->queue->hdr_digest) {
 		pdu->hdr.flags |= NVME_TCP_F_HDGST;
-		nvmet_tcp_hdgst(queue->snd_hash, pdu, sizeof(*pdu));
+		nvmet_tcp_hdgst(pdu, sizeof(*pdu));
 	}
 }
 
@@ -857,42 +860,6 @@ static void nvmet_prepare_receive_pdu(struct nvmet_tcp_queue *queue)
 	smp_store_release(&queue->rcv_state, NVMET_TCP_RECV_PDU);
 }
 
-static void nvmet_tcp_free_crypto(struct nvmet_tcp_queue *queue)
-{
-	struct crypto_ahash *tfm = crypto_ahash_reqtfm(queue->rcv_hash);
-
-	ahash_request_free(queue->rcv_hash);
-	ahash_request_free(queue->snd_hash);
-	crypto_free_ahash(tfm);
-}
-
-static int nvmet_tcp_alloc_crypto(struct nvmet_tcp_queue *queue)
-{
-	struct crypto_ahash *tfm;
-
-	tfm = crypto_alloc_ahash("crc32c", 0, CRYPTO_ALG_ASYNC);
-	if (IS_ERR(tfm))
-		return PTR_ERR(tfm);
-
-	queue->snd_hash = ahash_request_alloc(tfm, GFP_KERNEL);
-	if (!queue->snd_hash)
-		goto free_tfm;
-	ahash_request_set_callback(queue->snd_hash, 0, NULL, NULL);
-
-	queue->rcv_hash = ahash_request_alloc(tfm, GFP_KERNEL);
-	if (!queue->rcv_hash)
-		goto free_snd_hash;
-	ahash_request_set_callback(queue->rcv_hash, 0, NULL, NULL);
-
-	return 0;
-free_snd_hash:
-	ahash_request_free(queue->snd_hash);
-free_tfm:
-	crypto_free_ahash(tfm);
-	return -ENOMEM;
-}
-
-
 static int nvmet_tcp_handle_icreq(struct nvmet_tcp_queue *queue)
 {
 	struct nvme_tcp_icreq_pdu *icreq = &queue->pdu.icreq;
@@ -921,11 +888,6 @@ static int nvmet_tcp_handle_icreq(struct nvmet_tcp_queue *queue)
 
 	queue->hdr_digest = !!(icreq->digest & NVME_TCP_HDR_DIGEST_ENABLE);
 	queue->data_digest = !!(icreq->digest & NVME_TCP_DATA_DIGEST_ENABLE);
-	if (queue->hdr_digest || queue->data_digest) {
-		ret = nvmet_tcp_alloc_crypto(queue);
-		if (ret)
-			return ret;
-	}
 
 	memset(icresp, 0, sizeof(*icresp));
 	icresp->hdr.type = nvme_tcp_icresp;
@@ -1247,7 +1209,7 @@ static void nvmet_tcp_prep_recv_ddgst(struct nvmet_tcp_cmd *cmd)
 {
 	struct nvmet_tcp_queue *queue = cmd->queue;
 
-	nvmet_tcp_calc_ddgst(queue->rcv_hash, cmd);
+	nvmet_tcp_calc_ddgst(cmd);
 	queue->offset = 0;
 	queue->left = NVME_TCP_DIGEST_LENGTH;
 	queue->rcv_state = NVMET_TCP_RECV_DDGST;
@@ -1620,8 +1582,6 @@ static void nvmet_tcp_release_queue_work(struct work_struct *w)
 	/* ->sock will be released by fput() */
 	fput(queue->sock->file);
 	nvmet_tcp_free_cmds(queue);
-	if (queue->hdr_digest || queue->data_digest)
-		nvmet_tcp_free_crypto(queue);
 	ida_free(&nvmet_tcp_queue_ida, queue->idx);
 	page_frag_cache_drain(&queue->pf_cache);
 	kfree(queue);