[PATCH v4 7/8] pdump: remove use of VLA

[Stephen Hemminger]

Replace variable length array with refactored loop so that
packets are processed in bursts of up to 32.

Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>

burstit
---
 lib/pdump/meson.build |  2 --
 lib/pdump/rte_pdump.c | 59 ++++++++++++++++++++++++++++---------------
 2 files changed, 39 insertions(+), 22 deletions(-)

diff --git a/lib/pdump/meson.build b/lib/pdump/meson.build
index 553dfdd5e6..da8d51b616 100644
--- a/lib/pdump/meson.build
+++ b/lib/pdump/meson.build
@@ -7,8 +7,6 @@ if is_windows
     subdir_done()
 endif
 
-cflags += no_wvla_cflag
-
 sources = files('rte_pdump.c')
 headers = files('rte_pdump.h')
 deps += ['ethdev', 'bpf', 'pcapng']
diff --git a/lib/pdump/rte_pdump.c b/lib/pdump/rte_pdump.c
index 305325847c..1ab605972a 100644
--- a/lib/pdump/rte_pdump.c
+++ b/lib/pdump/rte_pdump.c
@@ -27,6 +27,8 @@ RTE_LOG_REGISTER_DEFAULT(pdump_logtype, NOTICE);
 /* Used for the multi-process communication */
 #define PDUMP_MP	"mp_pdump"
 
+#define PDUMP_BURST_SIZE	32
+
 /* Overly generous timeout for secondary to respond */
 #define MP_TIMEOUT_S 5
 
@@ -135,27 +137,22 @@ pdump_cb_release(struct pdump_rxtx_cbs *cbs)
 
 /* Create a clone of mbuf to be placed into ring. */
 static void
-pdump_copy(uint16_t port_id, uint16_t queue,
-	   enum rte_pcapng_direction direction,
-	   struct rte_mbuf **pkts, uint16_t nb_pkts,
-	   const struct pdump_rxtx_cbs *cbs,
-	   struct rte_pdump_stats *stats)
+pdump_copy_burst(uint16_t port_id, uint16_t queue_id,
+		 enum rte_pcapng_direction direction,
+		 struct rte_mbuf **pkts, uint16_t nb_pkts,
+		 const struct pdump_rxtx_cbs *cbs,
+		 struct rte_pdump_stats *stats)
 {
-	unsigned int i;
-	int ring_enq;
-	uint16_t d_pkts = 0;
-	struct rte_mbuf *dup_bufs[nb_pkts];
-	struct rte_ring *ring;
-	struct rte_mempool *mp;
-	struct rte_mbuf *p;
-	uint64_t rcs[nb_pkts];
+	uint16_t d_pkts = 0;                         /* number of duplicated packets */
+	struct rte_mbuf *dup_bufs[PDUMP_BURST_SIZE]; /* duplicated packets */
+	uint64_t rcs[PDUMP_BURST_SIZE];		     /* filter result */
+
+	RTE_ASSERT(nb_pkts <= PDUMP_BURST_SIZE);
 
 	if (cbs->filter)
 		rte_bpf_exec_burst(cbs->filter, (void **)pkts, rcs, nb_pkts);
 
-	ring = cbs->ring;
-	mp = cbs->mp;
-	for (i = 0; i < nb_pkts; i++) {
+	for (unsigned int i = 0; i < nb_pkts; i++) {
 		/*
 		 * This uses same BPF return value convention as socket filter
 		 * and pcap_offline_filter.
@@ -172,12 +169,12 @@ pdump_copy(uint16_t port_id, uint16_t queue,
 		 * If using pcapng then want to wrap packets
 		 * otherwise a simple copy.
 		 */
+		struct rte_mbuf *p;
 		if (cbs->ver == V2)
-			p = rte_pcapng_copy(port_id, queue,
-					    pkts[i], mp, cbs->snaplen,
+			p = rte_pcapng_copy(port_id, queue_id, pkts[i], cbs->mp, cbs->snaplen,
 					    direction, NULL);
 		else
-			p = rte_pktmbuf_copy(pkts[i], mp, 0, cbs->snaplen);
+			p = rte_pktmbuf_copy(pkts[i], cbs->mp, 0, cbs->snaplen);
 
 		if (unlikely(p == NULL))
 			rte_atomic_fetch_add_explicit(&stats->nombuf, 1, rte_memory_order_relaxed);
@@ -185,9 +182,13 @@ pdump_copy(uint16_t port_id, uint16_t queue,
 			dup_bufs[d_pkts++] = p;
 	}
 
+	if (d_pkts == 0)
+		return;
+
 	rte_atomic_fetch_add_explicit(&stats->accepted, d_pkts, rte_memory_order_relaxed);
 
-	ring_enq = rte_ring_enqueue_burst(ring, (void *)&dup_bufs[0], d_pkts, NULL);
+	unsigned int ring_enq
+		= rte_ring_enqueue_burst(cbs->ring, (void *)&dup_bufs[0], d_pkts, NULL);
 	if (unlikely(ring_enq < d_pkts)) {
 		unsigned int drops = d_pkts - ring_enq;
 
@@ -196,6 +197,24 @@ pdump_copy(uint16_t port_id, uint16_t queue,
 	}
 }
 
+/* Create a clone of mbuf to be placed into ring. */
+static void
+pdump_copy(uint16_t port_id, uint16_t queue_id,
+	   enum rte_pcapng_direction direction,
+	   struct rte_mbuf **pkts, uint16_t nb_pkts,
+	   const struct pdump_rxtx_cbs *cbs,
+	   struct rte_pdump_stats *stats)
+{
+	unsigned int offs = 0;
+
+	do {
+		unsigned int n = RTE_MIN(nb_pkts - offs, PDUMP_BURST_SIZE);
+
+		pdump_copy_burst(port_id, queue_id, direction, &pkts[offs], n, cbs, stats);
+		offs += n;
+	} while (offs < nb_pkts);
+}
+
 static uint16_t
 pdump_rx(uint16_t port, uint16_t queue,
 	struct rte_mbuf **pkts, uint16_t nb_pkts,
-- 
2.51.0