diff options
| author | Gang Yan <yangang@kylinos.cn> | 2026-04-03 14:29:27 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-04-07 05:14:26 +0300 |
| commit | 00d46be3c319029bdf5b4eb53bff8e47a8e7ddc4 (patch) | |
| tree | d293a69973dda1448411327e6e94f6cf7bc73493 | |
| parent | ede3136e56557498ec3f2e6da58cb0920d8074e1 (diff) | |
| download | linux-00d46be3c319029bdf5b4eb53bff8e47a8e7ddc4.tar.xz | |
mptcp: reduce 'overhead' from u16 to u8
The 'overhead' in struct mptcp_data_frag can safely use u8, as it
represents 'alignment + sizeof(mptcp_data_frag)'. With a maximum
alignment of 7('ALIGN(1, sizeof(long)) - 1'), the overhead is at most
47, well below U8_MAX and validated with BUILD_BUG_ON().
This patch also adds a field named 'unused' for further extensions.
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260403-net-next-mptcp-msg_eor-misc-v1-1-b0b33bea3fed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/mptcp/protocol.c | 6 | ||||
| -rw-r--r-- | net/mptcp/protocol.h | 3 |
2 files changed, 8 insertions, 1 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 239fb9e75c7c..79315e575d07 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -4616,6 +4616,12 @@ void __init mptcp_proto_init(void) inet_register_protosw(&mptcp_protosw); BUILD_BUG_ON(sizeof(struct mptcp_skb_cb) > sizeof_field(struct sk_buff, cb)); + + /* struct mptcp_data_frag: 'overhead' corresponds to the alignment + * (ALIGN(1, sizeof(long)) - 1, so 8-1) + the struct's size + */ + BUILD_BUG_ON(ALIGN(1, sizeof(long)) - 1 + sizeof(struct mptcp_data_frag) + > U8_MAX); } #if IS_ENABLED(CONFIG_MPTCP_IPV6) diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 0bd1ee860316..02031007100b 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -263,7 +263,8 @@ struct mptcp_data_frag { u64 data_seq; u16 data_len; u16 offset; - u16 overhead; + u8 overhead; + u8 __unused; u16 already_sent; struct page *page; }; |