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From: Laurent Vivier <lvivier@redhat.com>
To: passt-dev@passt.top
Cc: Laurent Vivier <lvivier@redhat.com>
Subject: [PATCH v8 30/30] packet: Add support for multi-vector packets
Date: Tue,  5 Aug 2025 17:46:28 +0200	[thread overview]
Message-ID: <20250805154628.301343-31-lvivier@redhat.com> (raw)
In-Reply-To: <20250805154628.301343-1-lvivier@redhat.com>

The packet pool was previously limited to handling packets contained
within a single buffer.

This patch extends the packet pool to support iovec array,
allowing a single logical packet to be composed of multiple iovec.

To accommodate this, the storage format within the pool is modified.
For a multi-vector packet, a header entry is now stored first with
iov_base = NULL and iov_len holding the number of subsequent
vectors. The actual data vectors are then stored in the following
pool slots.

The packet_add_do() and packet_get_do() functions are updated to
manage this new format for storing and retrieving packets. The
pool_full() check is also adjusted to ensure there is enough
space for all vectors of a new packet before adding it.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 packet.c | 50 +++++++++++++++++++++++++++++++++-----------------
 packet.h |  2 +-
 tap.c    |  4 ++--
 3 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/packet.c b/packet.c
index 4b93688509a4..d697232d951a 100644
--- a/packet.c
+++ b/packet.c
@@ -90,12 +90,13 @@ static int packet_check_range(const struct pool *p, const char *ptr, size_t len,
 /**
  * pool_full() - Is a packet pool full?
  * @p:		Pointer to packet pool
+ * @data:	check data can fit in the pool
  *
- * Return: true if the pool is full, false if more packets can be added
+ * Return: true if the pool is full, false if data can be added
  */
-bool pool_full(const struct pool *p)
+bool pool_full(const struct pool *p, const struct iov_tail *data)
 {
-	return p->count >= p->size;
+	return p->count + data->cnt  + (data->cnt > 1) >= p->size;
 }
 
 /**
@@ -108,11 +109,9 @@ bool pool_full(const struct pool *p)
 void packet_add_do(struct pool *p, struct iov_tail *data,
 		   const char *func, int line)
 {
-	size_t idx = p->count;
-	const char *start;
-	size_t len;
+	size_t idx = p->count, i, offset;
 
-	if (pool_full(p)) {
+	if (pool_full(p, data)) {
 		debug("add packet index %zu to pool with size %zu, %s:%i",
 		      idx, p->size, func, line);
 		return;
@@ -121,18 +120,30 @@ void packet_add_do(struct pool *p, struct iov_tail *data,
 	if (!iov_tail_prune(data))
 		return;
 
-	ASSERT(data->cnt == 1); /* we don't support iovec */
+	if (data->cnt > 1) {
+		p->pkt[idx].iov_base = NULL;
+		p->pkt[idx].iov_len = data->cnt;
+		idx++;
+	}
 
-	len = data->iov[0].iov_len - data->off;
-	start = (char *)data->iov[0].iov_base + data->off;
+	offset = data->off;
+	for (i = 0; i < data->cnt; i++) {
+		const char *start;
+		size_t len;
 
-	if (packet_check_range(p, start, len, func, line))
-		return;
+		len = data->iov[i].iov_len - offset;
+		start = (char *)data->iov[i].iov_base + offset;
+		offset = 0;
 
-	p->pkt[idx].iov_base = (void *)start;
-	p->pkt[idx].iov_len = len;
+		if (packet_check_range(p, start, len, func, line))
+			return;
 
-	p->count++;
+		p->pkt[idx].iov_base = (void *)start;
+		p->pkt[idx].iov_len = len;
+		idx++;
+	}
+
+	p->count = idx;
 }
 
 /**
@@ -162,9 +173,14 @@ bool packet_get_do(const struct pool *p, size_t idx,
 		return false;
 	}
 
-	data->cnt = 1;
+	if (p->pkt[idx].iov_base) {
+		data->cnt = 1;
+		data->iov = &p->pkt[idx];
+	} else {
+		data->cnt = p->pkt[idx].iov_len;
+		data->iov = &p->pkt[idx + 1];
+	}
 	data->off = 0;
-	data->iov = &p->pkt[idx];
 
 	for (i = 0; i < data->cnt; i++) {
 		ASSERT_WITH_MSG(!packet_check_range(p, data->iov[i].iov_base,
diff --git a/packet.h b/packet.h
index e51cbd19fdc4..67dc7deb17db 100644
--- a/packet.h
+++ b/packet.h
@@ -37,7 +37,7 @@ void packet_add_do(struct pool *p, struct iov_tail *data,
 		   const char *func, int line);
 bool packet_get_do(const struct pool *p, const size_t idx,
 		   struct iov_tail *data, const char *func, int line);
-bool pool_full(const struct pool *p);
+bool pool_full(const struct pool *p, const struct iov_tail *data);
 void pool_flush(struct pool *p);
 
 #define packet_add(p, data)					\
diff --git a/tap.c b/tap.c
index 9fd00915bb01..95688b22fcb7 100644
--- a/tap.c
+++ b/tap.c
@@ -1103,14 +1103,14 @@ void tap_add_packet(struct ctx *c, struct iov_tail *data,
 	switch (ntohs(eh->h_proto)) {
 	case ETH_P_ARP:
 	case ETH_P_IP:
-		if (pool_full(pool_tap4)) {
+		if (pool_full(pool_tap4, data)) {
 			tap4_handler(c, pool_tap4, now);
 			pool_flush(pool_tap4);
 		}
 		packet_add(pool_tap4, data);
 		break;
 	case ETH_P_IPV6:
-		if (pool_full(pool_tap6)) {
+		if (pool_full(pool_tap6, data)) {
 			tap6_handler(c, pool_tap6, now);
 			pool_flush(pool_tap6);
 		}
-- 
@@ -1103,14 +1103,14 @@ void tap_add_packet(struct ctx *c, struct iov_tail *data,
 	switch (ntohs(eh->h_proto)) {
 	case ETH_P_ARP:
 	case ETH_P_IP:
-		if (pool_full(pool_tap4)) {
+		if (pool_full(pool_tap4, data)) {
 			tap4_handler(c, pool_tap4, now);
 			pool_flush(pool_tap4);
 		}
 		packet_add(pool_tap4, data);
 		break;
 	case ETH_P_IPV6:
-		if (pool_full(pool_tap6)) {
+		if (pool_full(pool_tap6, data)) {
 			tap6_handler(c, pool_tap6, now);
 			pool_flush(pool_tap6);
 		}
-- 
2.49.0


  parent reply	other threads:[~2025-08-05 15:47 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-05 15:45 [PATCH v8 00/30] Introduce discontiguous frames management Laurent Vivier
2025-08-05 15:45 ` [PATCH v8 01/30] arp: Don't mix incoming and outgoing buffers Laurent Vivier
2025-08-05 15:46 ` [PATCH v8 02/30] iov: Introduce iov_tail_clone() and iov_tail_drop() Laurent Vivier
2025-08-06  1:32   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 03/30] iov: Update IOV_REMOVE_HEADER() and IOV_PEEK_HEADER() Laurent Vivier
2025-08-06  1:45   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 04/30] tap: Use iov_tail with tap_add_packet() Laurent Vivier
2025-08-06  1:56   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 05/30] packet: Use iov_tail with packet_add() Laurent Vivier
2025-08-05 15:46 ` [PATCH v8 06/30] packet: Add packet_data() Laurent Vivier
2025-08-06  2:14   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 07/30] arp: Convert to iov_tail Laurent Vivier
2025-08-06  2:17   ` David Gibson
2025-08-07 12:58     ` Laurent Vivier
2025-08-07 13:11       ` Stefano Brivio
2025-08-13  2:21         ` David Gibson
2025-08-05 15:46 ` [PATCH v8 08/30] ndp: " Laurent Vivier
2025-08-05 15:46 ` [PATCH v8 09/30] icmp: " Laurent Vivier
2025-08-06  2:20   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 10/30] udp: " Laurent Vivier
2025-08-06  2:23   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 11/30] tcp: Convert tcp_tap_handler() to use iov_tail Laurent Vivier
2025-08-06  2:35   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 12/30] tcp: Convert tcp_data_from_tap() " Laurent Vivier
2025-08-06  2:37   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 13/30] dhcpv6: move offset initialization out of dhcpv6_opt() Laurent Vivier
2025-08-05 15:46 ` [PATCH v8 14/30] dhcpv6: Extract sending of NotOnLink status Laurent Vivier
2025-08-05 15:46 ` [PATCH v8 15/30] dhcpv6: Convert to iov_tail Laurent Vivier
2025-08-05 15:46 ` [PATCH v8 16/30] dhcpv6: Use iov_tail in dhcpv6_opt() Laurent Vivier
2025-08-06  4:14   ` David Gibson
2025-08-08 13:59     ` Laurent Vivier
2025-08-13  2:29       ` David Gibson
2025-08-05 15:46 ` [PATCH v8 17/30] dhcp: Convert to iov_tail Laurent Vivier
2025-08-06  4:38   ` David Gibson
2025-08-08  9:33     ` Laurent Vivier
2025-08-13  2:27       ` David Gibson
2025-08-05 15:46 ` [PATCH v8 18/30] ip: Use iov_tail in ipv6_l4hdr() Laurent Vivier
2025-08-06  5:12   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 19/30] tap: Convert tap4_handler() to iov_tail Laurent Vivier
2025-08-06  5:17   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 20/30] tap: Convert tap6_handler() " Laurent Vivier
2025-08-06  6:21   ` David Gibson
2025-08-08 13:57     ` Laurent Vivier
2025-08-13  3:22       ` David Gibson
2025-08-05 15:46 ` [PATCH v8 21/30] packet: rename packet_data() to packet_get() Laurent Vivier
2025-08-06  6:22   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 22/30] arp: use iov_tail rather than pool Laurent Vivier
2025-08-06  6:24   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 23/30] dhcp: " Laurent Vivier
2025-08-06  6:26   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 24/30] dhcpv6: " Laurent Vivier
2025-08-06  6:27   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 25/30] icmp: " Laurent Vivier
2025-08-06  6:29   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 26/30] ndp: " Laurent Vivier
2025-08-06  6:31   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 27/30] packet: remove PACKET_POOL() and PACKET_POOL_P() Laurent Vivier
2025-08-06  6:32   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 28/30] packet: remove unused parameter from PACKET_POOL_DECL() Laurent Vivier
2025-08-06  6:33   ` David Gibson
2025-08-05 15:46 ` [PATCH v8 29/30] packet: Refactor vhost-user memory region handling Laurent Vivier
2025-08-07  6:10   ` David Gibson
2025-08-07  9:05     ` Laurent Vivier
2025-08-07 11:44       ` David Gibson
2025-08-05 15:46 ` Laurent Vivier [this message]
2025-08-07  6:17   ` [PATCH v8 30/30] packet: Add support for multi-vector packets David Gibson

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