* [PATCH net-next] mptcp: change mptcp_established_options() to return opt_size
[not found] <20260601091816.444738-1-edumazet@google.com>
@ 2026-06-01 9:47 ` Matthieu Baerts
2026-06-01 10:09 ` MPTCP CI
2026-06-01 11:12 ` MPTCP CI
0 siblings, 2 replies; 4+ messages in thread
From: Matthieu Baerts @ 2026-06-01 9:47 UTC (permalink / raw)
To: MPTCP Linux
From: Eric Dumazet <edumazet@google.com>
Instead of passing opt_size address to mptcp_established_options(),
change this function to return it by value.
This removes the need for an expensive stack canary in
tcp_established_options() when CONFIG_STACKPROTECTOR_STRONG=y.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-92 (-92)
Function old new delta
tcp_options_write.isra 1423 1407 -16
mptcp_established_options 2746 2720 -26
tcp_established_options 553 503 -50
Total: Before=22110750, After=22110658, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
include/net/mptcp.h | 18 +++++++++---------
net/ipv4/tcp_output.c | 7 ++++---
net/mptcp/options.c | 31 ++++++++++++++++---------------
3 files changed, 29 insertions(+), 27 deletions(-)
diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index f7263fe2a2e40b507257c3720cc2d78d37357d6d..cd4639beceaa53c573135ddaeb7528a80b4ca824 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -149,9 +149,9 @@ bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
unsigned int *size, struct mptcp_out_options *opts);
bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
struct mptcp_out_options *opts);
-bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
- unsigned int *size, unsigned int remaining,
- struct mptcp_out_options *opts);
+int mptcp_established_options(struct sock *sk, struct sk_buff *skb,
+ unsigned int remaining,
+ struct mptcp_out_options *opts);
bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb);
void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp,
@@ -266,13 +266,13 @@ static inline bool mptcp_synack_options(const struct request_sock *req,
return false;
}
-static inline bool mptcp_established_options(struct sock *sk,
- struct sk_buff *skb,
- unsigned int *size,
- unsigned int remaining,
- struct mptcp_out_options *opts)
+static inline int mptcp_established_options(struct sock *sk,
+ struct sk_buff *skb,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
{
- return false;
+ return -1;
}
static inline bool mptcp_incoming_options(struct sock *sk,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index ef0c10cd31c71ff585a937fde37f2b08b1214b5a..31b459ecbe8307a8660623038fea6fa7b0860f7f 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1181,10 +1181,11 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
*/
if (sk_is_mptcp(sk)) {
unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
- unsigned int opt_size = 0;
+ int opt_size;
- if (mptcp_established_options(sk, skb, &opt_size, remaining,
- &opts->mptcp)) {
+ opt_size = mptcp_established_options(sk, skb, remaining,
+ &opts->mptcp);
+ if (opt_size >= 0) {
opts->options |= OPTION_MPTCP;
size += opt_size;
}
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 8a1c5698983cff3082d68290626dd8f1e044527f..53528301394d70072dde6614feca6128ea949436 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -836,13 +836,14 @@ static bool mptcp_established_options_mp_fail(struct sock *sk,
return true;
}
-bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
- unsigned int *size, unsigned int remaining,
- struct mptcp_out_options *opts)
+int mptcp_established_options(struct sock *sk, struct sk_buff *skb,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
unsigned int opt_size = 0;
+ int total_size = 0;
bool snd_data_fin;
bool ret = false;
@@ -852,20 +853,20 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
* option space.
*/
if (unlikely(__mptcp_check_fallback(msk) && !mptcp_check_infinite_map(skb)))
- return true;
+ return 0;
if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
if (mptcp_established_options_fastclose(sk, &opt_size, remaining, opts) ||
mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) {
- *size += opt_size;
+ total_size += opt_size;
remaining -= opt_size;
}
/* MP_RST can be used with MP_FASTCLOSE and MP_FAIL if there is room */
if (mptcp_established_options_rst(sk, skb, &opt_size, remaining, opts)) {
- *size += opt_size;
+ total_size += opt_size;
remaining -= opt_size;
}
- return true;
+ return total_size;
}
snd_data_fin = mptcp_data_fin_enabled(msk);
@@ -877,9 +878,9 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
ret = true;
if (mptcp_established_options_mp_fail(sk, &mp_fail_size,
remaining - opt_size, opts)) {
- *size += opt_size + mp_fail_size;
+ total_size += opt_size + mp_fail_size;
remaining -= opt_size - mp_fail_size;
- return true;
+ return total_size;
}
}
@@ -887,27 +888,27 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
* TCP option space would be fatal
*/
if (WARN_ON_ONCE(opt_size > remaining))
- return false;
+ return -1;
- *size += opt_size;
+ total_size += opt_size;
remaining -= opt_size;
if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) {
- *size += opt_size;
+ total_size += opt_size;
remaining -= opt_size;
ret = true;
} else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
- *size += opt_size;
+ total_size += opt_size;
remaining -= opt_size;
ret = true;
}
if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) {
- *size += opt_size;
+ total_size += opt_size;
remaining -= opt_size;
ret = true;
}
- return ret;
+ return ret ? total_size : -1;
}
bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
--
2.54.0.1013.g208068f2d8-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread