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mptcp: change mptcp_established_options() to return opt_size

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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>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260602125138.2317015-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-06-02 12:51:38 +00:00 committed by Jakub Kicinski
parent 3070d0294e
commit a02a765bd5
3 changed files with 28 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
include/net/mptcp.h
View File

@ -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 +266,12 @@ 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 remaining,
struct mptcp_out_options *opts)
{
return false;
return -1;
}
static inline bool mptcp_incoming_options(struct sock *sk,

7
net/ipv4/tcp_output.c
View File

@ -1183,10 +1183,11 @@ 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;
}

31
net/mptcp/options.c
View File

@ -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,