Re: [PATCH bpf 1/2] bpf: drop duplicate check_app_limited in tcp_bpf_push
From: Jiayuan Chen <jiayuan.chen@linux.dev>
Date: 2026-09-14 08:24:31
Also in:
bpf, mptcp
On 9/14/26 3:14 PM, Geliang Tang wrote:
From: Geliang Tang <redacted>
When the sendpage->MSG_SPLICE_PAGES migration series replaced
do_tcp_sendpages() with direct tcp_sendmsg_locked() calls, callers that
had used do_tcp_sendpages() kept an explicit tcp_rate_check_app_limited(sk)
that was originally needed to cover do_tcp_sendpages() (which did not call
tcp_rate_check_app_limited()). After the inlining, tcp_sendmsg_locked()
always provides the check, and the outer call became redundant.
The site changed here, tcp_bpf_push(), is a MSG_SPLICE_PAGES loop that
holds the socket lock and only iterates when size > 0; tcp_sendmsg_locked()
is invoked on every iteration with state identical to what the outer call
sees, so dropping the outer call is safe and behavior-preserving.
A potential benefit of this change is that it facilitates future reuse of
tcp_bpf_push() for sockmap support in protocols beyond TCP, such as MPTCP.
Since tcp_rate_check_app_limited() is TCP-specific while sendmsg_locked()
is a generic interface in struct proto_ops, this change allows us to switch
to different protocols via sk->sk_socket->ops->sendmsg_locked() without
carrying protocol-specific assumptions.
Fixes: ebf2e8860eea ("tcp_bpf: Inline do_tcp_sendpages as it's now a wrapper around tcp_sendmsg")Same as the tls one: this looks like a cleanup to me. Is there a real regression that affects kernel or user behavior? Do we really need a Fixes tag?
quoted hunk ↗ jump to hunk
Signed-off-by: Geliang Tang <redacted> --- net/ipv4/tcp_bpf.c | 1 - 1 file changed, 1 deletion(-)diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 2e234d155b5e..d5fcf3ce4861 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c@@ -108,7 +108,6 @@ static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes, off = sge->offset; page = sg_page(sge); - tcp_rate_check_app_limited(sk); retry: msghdr.msg_flags = flags | MSG_SPLICE_PAGES; has_tx_ulp = tls_sw_has_ctx_tx(sk);