From 337d424d4f9e10b4a4cce4b8038082779a49c522 Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Tue, 26 May 2026 20:13:42 -0700
Subject: [PATCH] [mlr] stop fast polls upon receiving response (#13149)

When a sleepy end device (where `Mle::IsRxOnWhenIdle()` returns
false) sends an MLR request, it initiates fast data polls via
`DataPollSender::SendFastPolls()` to quickly receive the response.
This commit updates `Manager::HandleResponse()` to call
`DataPollSender::StopFastPolls()` when the MLR response is processed
by a sleepy end device. This ensures that the device does not
unnecessarily continue fast polling.
---
 src/core/thread/mlr_manager.cpp | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/core/thread/mlr_manager.cpp b/src/core/thread/mlr_manager.cpp
index d850887a0..72c9a28d8 100644
--- a/src/core/thread/mlr_manager.cpp
+++ b/src/core/thread/mlr_manager.cpp
@@ -419,9 +419,13 @@ void Manager::SendNextRequest(void)
 
     EnterState(kStateRegistering);
 
-    // Generally Thread 1.2 Router would send MLR.req on behalf for MA (scope >=4) subscribed by its MTD child.
-    // When Thread 1.2 MTD attaches to Thread 1.1 parent, 1.2 MTD should send MLR.req to PBBR itself.
-    // In this case, Thread 1.2 sleepy end device relies on fast data poll to fetch the response timely.
+    // Generally, a Thread 1.2 Router sends MLR.req on behalf of its
+    // MTD children for multicast addresses. However, when a Thread
+    // 1.2 MTD child attaches to a Thread 1.1 parent, the MTD child
+    // must send the MLR.req to the PBBR itself. In this scenario, a
+    // Thread 1.2 Sleepy End Device relies on fast data polls to
+    // receive the response in a timely manner.
+
     if (!Get<Mle::Mle>().IsRxOnWhenIdle())
     {
         Get<DataPollSender>().SendFastPolls();
@@ -551,6 +555,11 @@ void Manager::ProcessResponse(Coap::Msg *aMsg, Error aResult)
     AddressArray            registeredAddresses;
     OwnedPtr<Coap::Message> requestMsg;
 
+    if (!Get<Mle::Mle>().IsRxOnWhenIdle())
+    {
+        Get<DataPollSender>().StopFastPolls();
+    }
+
     //- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     // Parse the response message