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authorJakub Kicinski <kuba@kernel.org>2026-04-07 17:14:38 -0700
committerPaolo Abeni <pabeni@redhat.com>2026-04-13 15:32:35 +0200
commitb025461303d87923abfaae6cc07ba8a83ddfd844 (patch)
tree02690b2290e25061ecc9de531ac676146ed9a18d /include
parentc7211b6e83342c71380c2e40ae46ce4a745b98b6 (diff)
downloadlwn-b025461303d87923abfaae6cc07ba8a83ddfd844.tar.gz
lwn-b025461303d87923abfaae6cc07ba8a83ddfd844.zip
tcp: update window_clamp when SO_RCVBUF is set
Commit under Fixes moved recomputing the window clamp to tcp_measure_rcv_mss() (when scaling_ratio changes). I suspect it missed the fact that we don't recompute the clamp when rcvbuf is set. Until scaling_ratio changes we are stuck with the old window clamp which may be based on the small initial buffer. scaling_ratio may never change. Inspired by Eric's recent commit d1361840f8c5 ("tcp: fix SO_RCVLOWAT and RCVBUF autotuning") plumb the user action thru to TCP and have it update the clamp. A smaller fix would be to just have tcp_rcvbuf_grow() adjust the clamp even if SOCK_RCVBUF_LOCK is set. But IIUC this is what we were trying to get away from in the first place. Fixes: a2cbb1603943 ("tcp: Update window clamping condition") Signed-off-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Eric Dumazet <edumaze@google.com> Link: https://patch.msgid.link/20260408001438.129165-1-kuba@kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/net.h1
-rw-r--r--include/net/tcp.h1
2 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/net.h b/include/linux/net.h
index a8e818de95b3..ca6a7bc5c9ae 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -223,6 +223,7 @@ struct proto_ops {
int (*sendmsg_locked)(struct sock *sk, struct msghdr *msg,
size_t size);
int (*set_rcvlowat)(struct sock *sk, int val);
+ void (*set_rcvbuf)(struct sock *sk, int val);
};
#define DECLARE_SOCKADDR(type, dst, src) \
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 0f09429ff4cb..dfa52ceefd23 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -516,6 +516,7 @@ void tcp_syn_ack_timeout(const struct request_sock *req);
int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
int flags);
int tcp_set_rcvlowat(struct sock *sk, int val);
+void tcp_set_rcvbuf(struct sock *sk, int val);
int tcp_set_window_clamp(struct sock *sk, int val);
static inline void