[PATCH trivial 0/3] tcp_vu: Remove redundant header field assignments

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[PATCH trivial] vu_common: Detach...

Laurent Vivier

20 Mar 2026 20 Mar '26

2:51 p.m.

tcp_vu_send_flag() and tcp_vu_prepare() set several header fields that are unconditionally overwritten by tcp_fill_headers() or tcp_prepare_flags() shortly after. This series removes: 1. eh->h_proto assignments in both tcp_vu_send_flag() and tcp_vu_prepare(), overwritten by tcp_fill_headers() 2. eh->h_source memcpy in tcp_vu_send_flag(), overwritten by eth_update_mac() called from tcp_fill_headers() 3. th->doff and th->ack assignments in tcp_vu_send_flag(), overwritten by tcp_prepare_flags() Laurent Vivier (3): tcp_vu: Remove redundant eh->h_proto assignments tcp_vu: Remove redundant eh->h_source assignment in tcp_vu_send_flag() tcp_vu: Remove redundant th->doff and th->ack in tcp_vu_send_flag() tcp_vu.c | 11 ----------- 1 file changed, 11 deletions(-) -- 2.53.0

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Laurent Vivier

20 Mar 20 Mar

2:51 p.m.

New subject: [PATCH trivial 1/3] tcp_vu: Remove redundant eh->h_proto assignments

tcp_fill_headers() unconditionally sets eh->h_proto based on whether ip4h or ip6h is non-NULL. The assignments in tcp_vu_send_flag() and tcp_vu_prepare() are therefore redundant and can be removed. Signed-off-by: Laurent Vivier --- tcp_vu.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/tcp_vu.c b/tcp_vu.c index fd734e857b3b..c616b1fec2bf 100644 --- a/tcp_vu.c +++ b/tcp_vu.c @@ -105,15 +105,11 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags) memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source)); if (CONN_V4(conn)) { - eh->h_proto = htons(ETH_P_IP); - ip4h = vu_ip(flags_elem[0].in_sg[0].iov_base); *ip4h = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP); th = vu_payloadv4(flags_elem[0].in_sg[0].iov_base); } else { - eh->h_proto = htons(ETH_P_IPV6); - ip6h = vu_ip(flags_elem[0].in_sg[0].iov_base); *ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP); th = vu_payloadv6(flags_elem[0].in_sg[0].iov_base); @@ -307,14 +303,10 @@ static void tcp_vu_prepare(const struct ctx *c, struct tcp_tap_conn *conn, /* initialize header */ if (!v6) { - eh->h_proto = htons(ETH_P_IP); - ip4h = vu_ip(base); *ip4h = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP); th = vu_payloadv4(base); } else { - eh->h_proto = htons(ETH_P_IPV6); - ip6h = vu_ip(base); *ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP); -- 2.53.0

Laurent Vivier

2:51 p.m.

New subject: [PATCH trivial 2/3] tcp_vu: Remove redundant eh->h_source assignment in tcp_vu_send_flag()

tcp_fill_headers() calls eth_update_mac(eh, NULL, omac) which unconditionally overwrites eh->h_source. The prior memcpy() setting it to c->our_tap_mac is therefore redundant. Signed-off-by: Laurent Vivier --- tcp_vu.c | 1 - 1 file changed, 1 deletion(-) diff --git a/tcp_vu.c b/tcp_vu.c index c616b1fec2bf..9c4e916b1b8d 100644 --- a/tcp_vu.c +++ b/tcp_vu.c @@ -102,7 +102,6 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags) eh = vu_eth(flags_elem[0].in_sg[0].iov_base); memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest)); - memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source)); if (CONN_V4(conn)) { ip4h = vu_ip(flags_elem[0].in_sg[0].iov_base); -- 2.53.0

Laurent Vivier

2:51 p.m.

New subject: [PATCH trivial 3/3] tcp_vu: Remove redundant th->doff and th->ack in tcp_vu_send_flag()

tcp_prepare_flags() unconditionally sets th->doff and th->ack, so setting them right after the memset() is redundant. Signed-off-by: Laurent Vivier --- tcp_vu.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/tcp_vu.c b/tcp_vu.c index 9c4e916b1b8d..7a348eb01248 100644 --- a/tcp_vu.c +++ b/tcp_vu.c @@ -115,8 +115,6 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags) } memset(th, 0, sizeof(*th)); - th->doff = sizeof(*th) / 4; - th->ack = 1; seq = conn->seq_to_tap; opts = (struct tcp_syn_opts *)(th + 1); -- 2.53.0

David Gibson

24 Mar 24 Mar

12:10 a.m.

New subject: [PATCH trivial 2/3] tcp_vu: Remove redundant eh->h_source assignment in tcp_vu_send_flag()

On Fri, Mar 20, 2026 at 02:51:15PM +0100, Laurent Vivier wrote:

...

tcp_fill_headers() calls eth_update_mac(eh, NULL, omac) which unconditionally overwrites eh->h_source. The prior memcpy() setting it to c->our_tap_mac is therefore redundant.

Signed-off-by: Laurent Vivier

Reviewed-by: David Gibson

...

--- tcp_vu.c | 1 - 1 file changed, 1 deletion(-)

diff --git a/tcp_vu.c b/tcp_vu.c index c616b1fec2bf..9c4e916b1b8d 100644 --- a/tcp_vu.c +++ b/tcp_vu.c @@ -102,7 +102,6 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags) eh = vu_eth(flags_elem[0].in_sg[0].iov_base);

memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest)); - memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source));

if (CONN_V4(conn)) { ip4h = vu_ip(flags_elem[0].in_sg[0].iov_base); -- 2.53.0

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson

David Gibson

12:08 a.m.

New subject: [PATCH trivial 1/3] tcp_vu: Remove redundant eh->h_proto assignments

On Fri, Mar 20, 2026 at 02:51:14PM +0100, Laurent Vivier wrote:

...

tcp_fill_headers() unconditionally sets eh->h_proto based on whether ip4h or ip6h is non-NULL. The assignments in tcp_vu_send_flag() and tcp_vu_prepare() are therefore redundant and can be removed.

Signed-off-by: Laurent Vivier

Reviewed-by: David Gibson

...

--- tcp_vu.c | 8 -------- 1 file changed, 8 deletions(-)

diff --git a/tcp_vu.c b/tcp_vu.c index fd734e857b3b..c616b1fec2bf 100644 --- a/tcp_vu.c +++ b/tcp_vu.c @@ -105,15 +105,11 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags) memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source));

if (CONN_V4(conn)) { - eh->h_proto = htons(ETH_P_IP); - ip4h = vu_ip(flags_elem[0].in_sg[0].iov_base); *ip4h = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP);

th = vu_payloadv4(flags_elem[0].in_sg[0].iov_base); } else { - eh->h_proto = htons(ETH_P_IPV6); - ip6h = vu_ip(flags_elem[0].in_sg[0].iov_base); *ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP); th = vu_payloadv6(flags_elem[0].in_sg[0].iov_base); @@ -307,14 +303,10 @@ static void tcp_vu_prepare(const struct ctx *c, struct tcp_tap_conn *conn, /* initialize header */

if (!v6) { - eh->h_proto = htons(ETH_P_IP); - ip4h = vu_ip(base); *ip4h = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP); th = vu_payloadv4(base); } else { - eh->h_proto = htons(ETH_P_IPV6); - ip6h = vu_ip(base); *ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP);

-- 2.53.0

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson

David Gibson

12:11 a.m.

New subject: [PATCH trivial 3/3] tcp_vu: Remove redundant th->doff and th->ack in tcp_vu_send_flag()

On Fri, Mar 20, 2026 at 02:51:16PM +0100, Laurent Vivier wrote:

...

tcp_prepare_flags() unconditionally sets th->doff and th->ack, so setting them right after the memset() is redundant.

Signed-off-by: Laurent Vivier

Reviewed-by: David Gibson

...

--- tcp_vu.c | 2 -- 1 file changed, 2 deletions(-)

diff --git a/tcp_vu.c b/tcp_vu.c index 9c4e916b1b8d..7a348eb01248 100644 --- a/tcp_vu.c +++ b/tcp_vu.c @@ -115,8 +115,6 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags) }

memset(th, 0, sizeof(*th)); - th->doff = sizeof(*th) / 4; - th->ack = 1;

seq = conn->seq_to_tap; opts = (struct tcp_syn_opts *)(th + 1); -- 2.53.0

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson

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David Gibson
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