From 117c8197d72ff16b8b5cc0e8e71a29e5d8ad8849 Mon Sep 17 00:00:00 2001
From: firest <enlanubo@gmail.com>
Date: Wed, 24 Jul 2024 18:33:15 +0800
Subject: [PATCH 1/2] fix(exclusive): allow the same client to resubscribe to
 an existing exclusive topic

---
 apps/emqx/src/emqx_exclusive_subscription.erl | 7 +++++++
 apps/emqx/test/emqx_exclusive_sub_SUITE.erl   | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/apps/emqx/src/emqx_exclusive_subscription.erl b/apps/emqx/src/emqx_exclusive_subscription.erl
index 3a9dc8014..095233fbb 100644
--- a/apps/emqx/src/emqx_exclusive_subscription.erl
+++ b/apps/emqx/src/emqx_exclusive_subscription.erl
@@ -117,6 +117,13 @@ try_subscribe(ClientId, Topic) ->
                 write
             ),
             allow;
+        [#exclusive_subscription{clientid = ClientId, topic = Topic}] ->
+            %% Fixed the issue-13476
+            %% In this feature, the user must manually call `unsubscribe` to release the lock,
+            %% but sometimes the node may go down for some reason,
+            %% then the client will reconnect to this node and resubscribe.
+            %% We need to allow resubscription, otherwise the lock will never be released.
+            allow;
         [_] ->
             deny
     end.
diff --git a/apps/emqx/test/emqx_exclusive_sub_SUITE.erl b/apps/emqx/test/emqx_exclusive_sub_SUITE.erl
index abbdb5f44..a859612b2 100644
--- a/apps/emqx/test/emqx_exclusive_sub_SUITE.erl
+++ b/apps/emqx/test/emqx_exclusive_sub_SUITE.erl
@@ -56,6 +56,8 @@ t_exclusive_sub(_) ->
     {ok, _} = emqtt:connect(C1),
     ?CHECK_SUB(C1, 0),
 
+    ?CHECK_SUB(C1, 0),
+
     {ok, C2} = emqtt:start_link([
         {clientid, <<"client2">>},
         {clean_start, false},

From 4f21594707432a5f93dbe428d263b1585fc3dd54 Mon Sep 17 00:00:00 2001
From: firest <enlanubo@gmail.com>
Date: Wed, 24 Jul 2024 18:59:06 +0800
Subject: [PATCH 2/2] chore: update changes

---
 changes/ce/fix-13515.en.md | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changes/ce/fix-13515.en.md

diff --git a/changes/ce/fix-13515.en.md b/changes/ce/fix-13515.en.md
new file mode 100644
index 000000000..775c21848
--- /dev/null
+++ b/changes/ce/fix-13515.en.md
@@ -0,0 +1 @@
+Fixed an issue where the same client could not subscribe to the same exclusive topic when the node was down for some reason.