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From: David Gibson <david@gibson.dropbear.id.au>
To: Stefano Brivio <sbrivio@redhat.com>, passt-dev@passt.top
Cc: David Gibson <david@gibson.dropbear.id.au>
Subject: [PATCH v2 15/18] tap: Use different io vector bases depending on tap type
Date: Fri,  9 Dec 2022 16:42:25 +1100	[thread overview]
Message-ID: <20221209054228.4085990-16-david@gibson.dropbear.id.au> (raw)
In-Reply-To: <20221209054228.4085990-1-david@gibson.dropbear.id.au>

Currently tap_send_frames() expects the frames it is given to include the
vnet_len field, even in pasta mode which doesn't use it (although it need
not be initialized in that case).  To match, tap_iov_base() and
tap_iov_len() construct the frame in that way.

This will inconvenience future changes, so alter things to set the buffers
to include just the frame needed by the tap backend type.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 tap.c | 5 ++---
 tap.h | 6 ++++--
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/tap.c b/tap.c
index d0dd72c..5ec6b70 100644
--- a/tap.c
+++ b/tap.c
@@ -317,8 +317,7 @@ static void tap_send_frames_pasta(struct ctx *c,
 	size_t i;
 
 	for (i = 0; i < n; i++) {
-		if (write(c->fd_tap, (char *)iov->iov_base + 4,
-			  iov->iov_len - 4) < 0) {
+		if (write(c->fd_tap, (char *)iov->iov_base, iov->iov_len) < 0) {
 			debug("tap write: %s", strerror(errno));
 			if (errno != EAGAIN && errno != EWOULDBLOCK)
 				tap_handler(c, c->fd_tap, EPOLLERR, NULL);
@@ -383,7 +382,7 @@ void tap_send_frames(struct ctx *c, const struct iovec *iov, size_t n)
 	else
 		tap_send_frames_pasta(c, iov, n);
 
-	pcap_multiple(iov, n, sizeof(uint32_t));
+	pcap_multiple(iov, n, c->mode == MODE_PASST ? sizeof(uint32_t) : 0);
 }
 
 /**
diff --git a/tap.h b/tap.h
index 8fe460a..40cf480 100644
--- a/tap.h
+++ b/tap.h
@@ -20,8 +20,10 @@ struct tap_hdr {
 
 static inline size_t tap_hdr_len_(const struct ctx *c)
 {
-	(void)c;
-	return sizeof(struct tap_hdr);
+	if (c->mode == MODE_PASST)
+		return sizeof(struct tap_hdr);
+	else
+		return sizeof(struct ethhdr);
 }
 
 /**
-- 
@@ -20,8 +20,10 @@ struct tap_hdr {
 
 static inline size_t tap_hdr_len_(const struct ctx *c)
 {
-	(void)c;
-	return sizeof(struct tap_hdr);
+	if (c->mode == MODE_PASST)
+		return sizeof(struct tap_hdr);
+	else
+		return sizeof(struct ethhdr);
 }
 
 /**
-- 
2.38.1


  parent reply	other threads:[~2022-12-09  5:42 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-09  5:42 [PATCH v2 00/18] RFC: Unify and simplify tap send path David Gibson
2022-12-09  5:42 ` [PATCH v2 01/18] pcap: Introduce pcap_frame() helper David Gibson
2023-01-04 17:45   ` Stefano Brivio
2023-01-05  4:47     ` David Gibson
2022-12-09  5:42 ` [PATCH v2 02/18] pcap: Replace pcapm() with pcap_multiple() David Gibson
2022-12-09  5:42 ` [PATCH v2 03/18] tcp: Combine two parts of passt tap send path together David Gibson
2022-12-09  5:42 ` [PATCH v2 04/18] tcp: Don't keep compute total bytes in a message until we need it David Gibson
2023-01-04 17:45   ` Stefano Brivio
2023-01-05  4:48     ` David Gibson
2022-12-09  5:42 ` [PATCH v2 05/18] tcp: Improve interface to tcp_l2_buf_flush() David Gibson
2023-01-04 17:45   ` Stefano Brivio
2023-01-05  4:53     ` David Gibson
2022-12-09  5:42 ` [PATCH v2 06/18] tcp: Combine two parts of pasta tap send path together David Gibson
2022-12-09  5:42 ` [PATCH v2 07/18] tap, tcp: Move tap send path to tap.c David Gibson
2022-12-09  5:42 ` [PATCH v2 08/18] util: Introduce hton*_constant() in place of #ifdefs David Gibson
2022-12-09  5:42 ` [PATCH v2 09/18] tcp, udp: Use named field initializers in iov_init functions David Gibson
2022-12-09  5:42 ` [PATCH v2 10/18] util: Parameterize ethernet header initializer macro David Gibson
2022-12-09  5:42 ` [PATCH v2 11/18] tcp: Remove redundant and incorrect initialization from *_iov_init() David Gibson
2022-12-09  5:42 ` [PATCH v2 12/18] tcp: Consolidate calculation of total frame size David Gibson
2022-12-09  5:42 ` [PATCH v2 13/18] tap: Add "tap headers" abstraction David Gibson
2022-12-09  5:42 ` [PATCH v2 14/18] tcp: Use abstracted tap header David Gibson
2022-12-09  5:42 ` David Gibson [this message]
2022-12-09  5:42 ` [PATCH v2 16/18] udp: " David Gibson
2022-12-09  5:42 ` [PATCH v2 17/18] udp: Use tap_send_frames() David Gibson
2023-01-04 17:45   ` Stefano Brivio
2023-01-05  4:54     ` David Gibson
2022-12-09  5:42 ` [PATCH v2 18/18] tap: Improve handling of partial frame sends David Gibson
2023-01-04 17:45   ` Stefano Brivio
2023-01-05  4:57     ` David Gibson
2023-01-04 17:45 ` [PATCH v2 00/18] RFC: Unify and simplify tap send path Stefano Brivio

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