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 3/4] udp: Preadjust udp[46]_l2_iov_tap[].iov_base for pasta mode
Date: Thu, 24 Nov 2022 19:54:20 +1100 [thread overview]
Message-ID: <20221124085421.3027886-4-david@gibson.dropbear.id.au> (raw)
In-Reply-To: <20221124085421.3027886-1-david@gibson.dropbear.id.au>
Currently, we always populate udp[46]_l2_iov_tap[].iov_base with the
very start of the header buffers, including space for the qemu vnet_len
tag suitable for passt mode. That's ok because we don't actually use these
iovecs for pasta mode.
However, we do know the mode in udp_sock[46]_iov_init() so adjust these
to the beginning of the headers we'll actually need for the mode: including
the vnet_len tag for passt, but excluding it for pasta.
This allows a slightly nicer way to locate the right buffer to send in the
pasta case, and will allow some additional cleanups later.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
udp.c | 36 ++++++++++++++++++------------------
1 file changed, 18 insertions(+), 18 deletions(-)
diff --git a/udp.c b/udp.c
index 6a34e85..e2eb504 100644
--- a/udp.c
+++ b/udp.c
@@ -314,8 +314,9 @@ void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s,
/**
* udp_sock4_iov_init() - Initialise scatter-gather L2 buffers for IPv4 sockets
+ * @c: Execution context
*/
-static void udp_sock4_iov_init(void)
+static void udp_sock4_iov_init(const struct ctx *c)
{
struct mmsghdr *h;
int i;
@@ -343,7 +344,11 @@ static void udp_sock4_iov_init(void)
for (i = 0, h = udp4_l2_mh_tap; i < UDP_MAX_FRAMES; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
- udp4_l2_iov_tap[i].iov_base = &udp4_l2_buf[i].vnet_len;
+ if (c->mode == MODE_PASTA)
+ udp4_l2_iov_tap[i].iov_base = &udp4_l2_buf[i].eh;
+ else
+ udp4_l2_iov_tap[i].iov_base = &udp4_l2_buf[i].vnet_len;
+
mh->msg_iov = &udp4_l2_iov_tap[i];
mh->msg_iovlen = 1;
}
@@ -351,8 +356,9 @@ static void udp_sock4_iov_init(void)
/**
* udp_sock6_iov_init() - Initialise scatter-gather L2 buffers for IPv6 sockets
+ * @c: Execution context
*/
-static void udp_sock6_iov_init(void)
+static void udp_sock6_iov_init(const struct ctx *c)
{
struct mmsghdr *h;
int i;
@@ -383,7 +389,11 @@ static void udp_sock6_iov_init(void)
for (i = 0, h = udp6_l2_mh_tap; i < UDP_MAX_FRAMES; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
- udp6_l2_iov_tap[i].iov_base = &udp6_l2_buf[i].vnet_len;
+ if (c->mode == MODE_PASTA)
+ udp6_l2_iov_tap[i].iov_base = &udp6_l2_buf[i].eh;
+ else
+ udp6_l2_iov_tap[i].iov_base = &udp6_l2_buf[i].vnet_len;
+
mh->msg_iov = &udp6_l2_iov_tap[i];
mh->msg_iovlen = 1;
}
@@ -681,16 +691,7 @@ static void udp_sock_fill_data_v4(const struct ctx *c, int n,
b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh));
if (c->mode == MODE_PASTA) {
- /* If we pass &b->eh directly to write(), starting from
- * gcc 12.1, at least on aarch64 and x86_64, we get a bogus
- * stringop-overread warning, due to:
- * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103483
- *
- * but we can't disable it with a pragma, because it will be
- * ignored if LTO is enabled:
- * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80922
- */
- void *frame = (char *)b + offsetof(struct udp4_l2_buf_t, eh);
+ void *frame = udp4_l2_iov_tap[n].iov_base;
if (write(c->fd_tap, frame, sizeof(b->eh) + ip_len) < 0)
debug("tap write: %s", strerror(errno));
@@ -792,8 +793,7 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
b->ip6h.hop_limit = 255;
if (c->mode == MODE_PASTA) {
- /* See udp_sock_fill_data_v4() for the reason behind 'frame' */
- void *frame = (char *)b + offsetof(struct udp6_l2_buf_t, eh);
+ void *frame = udp6_l2_iov_tap[n].iov_base;
if (write(c->fd_tap, frame, sizeof(b->eh) + ip_len) < 0)
debug("tap write: %s", strerror(errno));
@@ -1227,10 +1227,10 @@ static void udp_splice_iov_init(void)
int udp_init(struct ctx *c)
{
if (c->ifi4)
- udp_sock4_iov_init();
+ udp_sock4_iov_init(c);
if (c->ifi6)
- udp_sock6_iov_init();
+ udp_sock6_iov_init(c);
udp_invert_portmap(&c->udp.fwd_in);
udp_invert_portmap(&c->udp.fwd_out);
--
@@ -314,8 +314,9 @@ void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s,
/**
* udp_sock4_iov_init() - Initialise scatter-gather L2 buffers for IPv4 sockets
+ * @c: Execution context
*/
-static void udp_sock4_iov_init(void)
+static void udp_sock4_iov_init(const struct ctx *c)
{
struct mmsghdr *h;
int i;
@@ -343,7 +344,11 @@ static void udp_sock4_iov_init(void)
for (i = 0, h = udp4_l2_mh_tap; i < UDP_MAX_FRAMES; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
- udp4_l2_iov_tap[i].iov_base = &udp4_l2_buf[i].vnet_len;
+ if (c->mode == MODE_PASTA)
+ udp4_l2_iov_tap[i].iov_base = &udp4_l2_buf[i].eh;
+ else
+ udp4_l2_iov_tap[i].iov_base = &udp4_l2_buf[i].vnet_len;
+
mh->msg_iov = &udp4_l2_iov_tap[i];
mh->msg_iovlen = 1;
}
@@ -351,8 +356,9 @@ static void udp_sock4_iov_init(void)
/**
* udp_sock6_iov_init() - Initialise scatter-gather L2 buffers for IPv6 sockets
+ * @c: Execution context
*/
-static void udp_sock6_iov_init(void)
+static void udp_sock6_iov_init(const struct ctx *c)
{
struct mmsghdr *h;
int i;
@@ -383,7 +389,11 @@ static void udp_sock6_iov_init(void)
for (i = 0, h = udp6_l2_mh_tap; i < UDP_MAX_FRAMES; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
- udp6_l2_iov_tap[i].iov_base = &udp6_l2_buf[i].vnet_len;
+ if (c->mode == MODE_PASTA)
+ udp6_l2_iov_tap[i].iov_base = &udp6_l2_buf[i].eh;
+ else
+ udp6_l2_iov_tap[i].iov_base = &udp6_l2_buf[i].vnet_len;
+
mh->msg_iov = &udp6_l2_iov_tap[i];
mh->msg_iovlen = 1;
}
@@ -681,16 +691,7 @@ static void udp_sock_fill_data_v4(const struct ctx *c, int n,
b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh));
if (c->mode == MODE_PASTA) {
- /* If we pass &b->eh directly to write(), starting from
- * gcc 12.1, at least on aarch64 and x86_64, we get a bogus
- * stringop-overread warning, due to:
- * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103483
- *
- * but we can't disable it with a pragma, because it will be
- * ignored if LTO is enabled:
- * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80922
- */
- void *frame = (char *)b + offsetof(struct udp4_l2_buf_t, eh);
+ void *frame = udp4_l2_iov_tap[n].iov_base;
if (write(c->fd_tap, frame, sizeof(b->eh) + ip_len) < 0)
debug("tap write: %s", strerror(errno));
@@ -792,8 +793,7 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
b->ip6h.hop_limit = 255;
if (c->mode == MODE_PASTA) {
- /* See udp_sock_fill_data_v4() for the reason behind 'frame' */
- void *frame = (char *)b + offsetof(struct udp6_l2_buf_t, eh);
+ void *frame = udp6_l2_iov_tap[n].iov_base;
if (write(c->fd_tap, frame, sizeof(b->eh) + ip_len) < 0)
debug("tap write: %s", strerror(errno));
@@ -1227,10 +1227,10 @@ static void udp_splice_iov_init(void)
int udp_init(struct ctx *c)
{
if (c->ifi4)
- udp_sock4_iov_init();
+ udp_sock4_iov_init(c);
if (c->ifi6)
- udp_sock6_iov_init();
+ udp_sock6_iov_init(c);
udp_invert_portmap(&c->udp.fwd_in);
udp_invert_portmap(&c->udp.fwd_out);
--
2.38.1
next prev parent reply other threads:[~2022-11-24 8:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-24 8:54 [PATCH 0/4] udp: Fix some confusion of IPv4 and IPv6 control structures David Gibson
2022-11-24 8:54 ` [PATCH 1/4] udp: Fix inorrect use of IPv6 mh buffers in IPv4 path David Gibson
2022-11-24 8:54 ` [PATCH 2/4] udp: Better factor IPv4 and IPv6 paths in udp_sock_handler() David Gibson
2022-11-24 8:54 ` David Gibson [this message]
2022-11-24 8:54 ` [PATCH 4/4] udp: Factor out control structure management from udp_sock_fill_data_v[46] David Gibson
2022-11-25 2:01 ` [PATCH 0/4] udp: Fix some confusion of IPv4 and IPv6 control structures Stefano Brivio
2022-11-25 7:11 ` David Gibson
2022-12-06 6:47 ` Stefano Brivio
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