[dpdk-dev] [PATCH v4] rte_mbuf: add rte_pktmbuf_linearize

[Tomasz Kulasek <tomaszx.kulasek@intel.com>]

This patch adds function rte_pktmbuf_linearize to let crypto PMD coalesce
chained mbuf before crypto operation and extend their capabilities to
support segmented mbufs when device cannot handle them natively.

Included unit tests for rte_pktmbuf_linearize functionality:

 1) Creates banch of segmented mbufs with different size and number of
    segments.
 2) Generates pkt_len bytes of random data.
 3) Fills noncontigouos mbuf with randomly generated data.
 4) Uses rte_pktmbuf_linearize to coalesce segmented buffer into one
    contiguous.
 5) Verifies data in linearized buffer.

Dependencies:

This patch is rebased to the dpdk-next-crypto and should be applied
before "Chained Mbufs support in SW PMDs" patchset.


changes in v4:
 - separated from "Chained Mbufs support in SW PMDs" patch set for
   better reviewing,
 - merged "rte_pktmbuf_linearize" implementation with unit tests,

changes in v3:
 - rebased to dpdk-next-crypto

changes in v2:
 - rte_pktmbuf_coalesce replaced with rte_pktmbuf_linearize


Cc: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Cc: Olivier Matz <olivier.matz@6wind.com>
Signed-off-by: Tomasz Kulasek <tomaszx.kulasek@intel.com>
---
 app/test/test_mbuf.c       |  123 ++++++++++++++++++++++++++++++++++++++++++++
 lib/librte_mbuf/rte_mbuf.h |   56 ++++++++++++++++++++
 2 files changed, 179 insertions(+)

diff --git a/app/test/test_mbuf.c b/app/test/test_mbuf.c
index c0823ea..39577e7 100644
--- a/app/test/test_mbuf.c
+++ b/app/test/test_mbuf.c
@@ -930,6 +930,124 @@
 	return 0;
 }
 
+static int
+test_mbuf_linearize(int pkt_len, int nb_segs) {
+
+	struct rte_mbuf *m = NULL, *mbuf_src = NULL;
+	uint8_t data[pkt_len], *src, *dst;
+	int data_len = 0;
+	int i, size;
+	int t_len;
+
+	if (pkt_len < 1) {
+		printf("Packet size must be 1 or more (is %d)\n", pkt_len);
+		return -1;
+	}
+
+	if (nb_segs < 1) {
+		printf("Number of segments must be 1 or more (is %d)\n",
+				nb_segs);
+		return -1;
+	}
+
+	/* Setup buffer */
+	for (i = 0; i < pkt_len; i++)
+		data[i] = (uint8_t) rte_rand();
+
+	t_len = pkt_len >= nb_segs ? pkt_len / nb_segs : 1;
+	src = data;
+	size = pkt_len;
+
+	/* Create chained mbuf_src and fill it generated data */
+	for (i = 0; size > 0; i++) {
+
+		m = rte_pktmbuf_alloc(pktmbuf_pool);
+		if (i == 0)
+			mbuf_src = m;
+
+		if (!m) {
+			printf("Cannot create segment for source mbuf");
+			goto fail;
+		}
+
+		/* Make sure if tailroom is zeroed */
+		memset(rte_pktmbuf_mtod(m, uint8_t *), 0,
+				rte_pktmbuf_tailroom(m));
+
+		data_len = size > t_len ? t_len : size;
+		dst = (uint8_t *)rte_pktmbuf_append(m, data_len);
+		if (!dst) {
+			printf("Cannot append %d bytes to the mbuf\n",
+					data_len);
+			goto fail;
+		}
+
+		rte_memcpy(dst, src, data_len);
+		src += data_len;
+
+		if (mbuf_src != m)
+			rte_pktmbuf_chain(mbuf_src, m);
+
+		size -= data_len;
+
+	}
+
+	/* Create destination buffer to store coalesced data */
+	if (rte_pktmbuf_linearize(mbuf_src)) {
+		printf("Mbuf linearization failed\n");
+		goto fail;
+	}
+
+	if (!rte_pktmbuf_is_contiguous(mbuf_src)) {
+		printf("Source buffer should be contiguous after "
+				"linearization\n");
+		goto fail;
+	}
+
+	src = rte_pktmbuf_mtod(mbuf_src, uint8_t *);
+
+	if (memcmp(src, data, rte_pktmbuf_pkt_len(mbuf_src))) {
+		printf("Incorrect data in coalesced mbuf\n");
+		goto fail;
+	}
+
+	if (mbuf_src)
+		rte_pktmbuf_free(mbuf_src);
+	return 0;
+
+fail:
+	if (mbuf_src)
+		rte_pktmbuf_free(mbuf_src);
+	return -1;
+}
+
+static int
+test_mbuf_linearize_check(void)
+{
+	struct test_mbuf_array {
+		int size;
+		int nb_segs;
+	} mbuf_array[5] = {
+			{ 128, 1 },
+			{ 64, 64 },
+			{ 512, 10 },
+			{ 250, 11 },
+			{ 123, 8 },
+	};
+	unsigned int i;
+
+	printf("Test mbuf linearize API\n");
+
+	for (i = 0; i < RTE_DIM(mbuf_array); i++)
+		if (test_mbuf_linearize(mbuf_array[i].size,
+				mbuf_array[i].nb_segs)) {
+			printf("Test failed for %d, %d\n", mbuf_array[i].size,
+					mbuf_array[i].nb_segs);
+			return -1;
+		}
+
+	return 0;
+}
 
 static int
 test_mbuf(void)
@@ -1023,6 +1141,11 @@
 		printf("test_failing_mbuf_sanity_check() failed\n");
 		return -1;
 	}
+
+	if (test_mbuf_linearize_check() < 0) {
+		printf("test_mbuf_linearize_check() failed\n");
+		return -1;
+	}
 	return 0;
 }
 
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index ead7c6e..b11a31d 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -1647,6 +1647,62 @@ static inline int rte_pktmbuf_chain(struct rte_mbuf *head, struct rte_mbuf *tail
 }
 
 /**
+ * Linearize data in mbuf.
+ *
+ * This function coalesce mbuf merging data in the first segment, unchaining
+ * rest, and then frees them.
+ *
+ * All operations are done in-place, so the structure of incoming mbuf
+ * is changed.
+ *
+ * @param mbuf
+ *   mbuf to linearize
+ * @return
+ *   - 0, on success
+ *   - -1, on error
+ */
+static inline int
+rte_pktmbuf_linearize(struct rte_mbuf *mbuf)
+{
+	int l, n;
+	struct rte_mbuf *m;
+	struct rte_mbuf *m_next;
+	char *buffer;
+
+	if (rte_pktmbuf_is_contiguous(mbuf))
+		return 0;
+
+	/* Extend first segment to the total packet length
+	 */
+	n = rte_pktmbuf_pkt_len(mbuf) - rte_pktmbuf_data_len(mbuf);
+
+	if (unlikely(n > rte_pktmbuf_tailroom(mbuf)))
+		return -1;
+
+	buffer = rte_pktmbuf_mtod_offset(mbuf, char *, mbuf->data_len);
+	mbuf->data_len = (uint16_t)(mbuf->pkt_len);
+
+	/* Append data from next segments to the first one
+	 */
+	m = mbuf->next;
+	while (m != NULL) {
+		m_next = m->next;
+
+		l = rte_pktmbuf_data_len(m);
+		rte_memcpy(buffer, rte_pktmbuf_mtod(m, char *), l);
+		buffer += l;
+
+		rte_pktmbuf_free_seg(m);
+		m = m_next;
+	}
+
+	mbuf->next = NULL;
+	mbuf->nb_segs = 1;
+
+	return 0;
+}
+
+/**
  * Dump an mbuf structure to a file.
  *
  * Dump all fields for the given packet mbuf and all its associated
-- 
1.7.9.5