From 080f406977cdd91ab8d7998cf79fc2be6339f8c7 Mon Sep 17 00:00:00 2001
From: Martin Braun <martin.braun@ettus.com>
Date: Wed, 17 Jul 2019 15:27:18 -0700
Subject: rfnoc: ctrlport_endpoint: Audit locks, lock more selectively

The existing implementation would lock judiciously, causing a deadlock
when the async message handler would try and call poke32().
---
 host/lib/rfnoc/ctrlport_endpoint.cpp | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

(limited to 'host/lib/rfnoc')

diff --git a/host/lib/rfnoc/ctrlport_endpoint.cpp b/host/lib/rfnoc/ctrlport_endpoint.cpp
index a618eaca2..267ff5d71 100644
--- a/host/lib/rfnoc/ctrlport_endpoint.cpp
+++ b/host/lib/rfnoc/ctrlport_endpoint.cpp
@@ -193,11 +193,13 @@ public:
 
     virtual void register_async_msg_handler(async_msg_callback_t callback_f)
     {
+        std::unique_lock<std::mutex> lock(_mutex);
         _handle_async_msg = callback_f;
     }
 
     virtual void set_policy(const std::string& name, const uhd::device_addr_t& args)
     {
+        std::unique_lock<std::mutex> lock(_mutex);
         if (name == "default") {
             _policy.timeout    = args.cast<double>("timeout", DEFAULT_TIMEOUT);
             _policy.force_acks = DEFAULT_FORCE_ACKS;
@@ -209,10 +211,10 @@ public:
 
     virtual void handle_recv(const ctrl_payload& rx_ctrl)
     {
-        std::unique_lock<std::mutex> lock(_mutex);
         if (rx_ctrl.is_ack) {
             // Function to process a response with no sequence errors
             auto process_correct_response = [this, rx_ctrl]() {
+                std::unique_lock<std::mutex> lock(_mutex);
                 response_status_t resp_status = RESP_VALID;
                 // Grant flow control credits
                 _buff_occupied -= get_payload_size(_req_queue.front());
@@ -228,6 +230,7 @@ public:
             };
             // Function to process a response with sequence errors
             auto process_incorrect_response = [this]() {
+                std::unique_lock<std::mutex> lock(_mutex);
                 // Grant flow control credits
                 _buff_occupied -= get_payload_size(_req_queue.front());
                 _buff_free_cond.notify_one();
@@ -286,7 +289,11 @@ public:
                 tx_ctrl.is_ack   = true;
                 tx_ctrl.src_epid = _my_epid;
                 tx_ctrl.status   = status;
-                _handle_send(tx_ctrl, _policy.timeout);
+                const auto timeout = [&]() {
+                    std::unique_lock<std::mutex> lock(_mutex);
+                    return _policy.timeout;
+                }();
+                _handle_send(tx_ctrl, timeout);
             } catch (...) {
                 UHD_LOG_ERROR("CTRLEP",
                     "Encountered an error sending a response for an async message");
@@ -296,11 +303,13 @@ public:
 
     virtual uint16_t get_src_epid() const
     {
+        // Is const, does not require a mutex
         return _my_epid;
     }
 
     virtual uint16_t get_port_num() const
     {
+        // Is const, does not require a mutex
         return _local_port;
     }
 
@@ -324,7 +333,6 @@ private:
         const uhd::time_spec_t& time_spec,
         const steady_clock::time_point& timeout_time)
     {
-        std::unique_lock<std::mutex> lock(_mutex);
 
         if (!_client_clk.is_running()) {
             throw uhd::system_error("Ctrlport client clock is not running");
@@ -353,6 +361,8 @@ private:
         tx_ctrl.op_code     = op_code;
         tx_ctrl.status      = CMD_OKAY;
 
+        std::unique_lock<std::mutex> lock(_mutex);
+
         // Perform flow control
         // If there is no room in the downstream buffer, then wait until the timeout
         size_t pyld_size   = get_payload_size(tx_ctrl);
@@ -383,10 +393,9 @@ private:
     const ctrl_payload wait_for_ack(
         const ctrl_payload& request, const steady_clock::time_point& timeout_time)
     {
-        std::unique_lock<std::mutex> lock(_mutex);
-
         auto resp_ready = [this]() -> bool { return !_resp_queue.empty(); };
         while (true) {
+            std::unique_lock<std::mutex> lock(_mutex);
             // Wait until there is a response in the response queue
             if (!resp_ready()) {
                 if (not _resp_ready_cond.wait_until(lock, timeout_time, resp_ready)) {
-- 
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