From 8882934f4dd994239085d009605d9852d195bf1d Mon Sep 17 00:00:00 2001
From: Eran <librealsense.eran@gmail.com>
Date: Wed, 11 Oct 2023 08:58:55 +0300
Subject: [PATCH] try to remove deadlock

---
 src/device.cpp | 45 +++++++++++++++++++++------------------------
 src/device.h   |  8 +++-----
 2 files changed, 24 insertions(+), 29 deletions(-)

diff --git a/src/device.cpp b/src/device.cpp
index 6cc93aea004..d43cdfce45f 100644
--- a/src/device.cpp
+++ b/src/device.cpp
@@ -169,34 +169,34 @@ matcher_factory::create_timestamp_composite_matcher( std::vector< std::shared_pt
 device::device(std::shared_ptr<context> ctx,
                const platform::backend_device_group group,
                bool device_changed_notifications)
-    : _context(ctx), _group(group), _is_valid(true),
-      _device_changed_notifications(device_changed_notifications),
-      _is_alive( std::make_shared< bool >( true ) )
+    : _context( ctx )
+    , _group( group )
+    , _device_changed_notifications( device_changed_notifications )
+    , _is_alive( std::make_shared< std::atomic< bool > >( true ) )
 {
     _profiles_tags = lazy<std::vector<tagged_profile>>([this]() { return get_profiles_tags(); });
 
     if (_device_changed_notifications)
     {
-        std::weak_ptr< bool > weak = _is_alive;
-        auto cb = new devices_changed_callback_internal([this, weak](rs2_device_list* removed, rs2_device_list* added)
-        {
-            // The callback can be called from one thread while the object is being destroyed by another.
-            // Check if members can still be accessed.
-            auto alive = weak.lock();
-            if( ! alive || ! *alive )
-                return;
-
-            // Update is_valid variable when device is invalid
-            std::lock_guard<std::mutex> lock(_device_changed_mtx);
-            for (auto& dev_info : removed->list)
+        std::weak_ptr< std::atomic< bool > > weak_alive = _is_alive;
+        auto cb = new devices_changed_callback_internal(
+            [weak_alive, group]( rs2_device_list * removed, rs2_device_list * added )
             {
-                if (dev_info.info->get_device_data() == _group)
-                {
-                    _is_valid = false;
+                // The callback can be called from one thread while the object is being destroyed by another.
+                // Check if members can still be accessed.
+                auto alive = weak_alive.lock();
+                if( ! alive || ! *alive )
                     return;
+
+                for( auto & dev_info : removed->list )
+                {
+                    if( dev_info.info->get_device_data() == group )
+                    {
+                        *alive = false;
+                        return;
+                    }
                 }
-            }
-        });
+            } );
 
         _callback_id = _context->register_internal_device_callback({ cb, [](rs2_devices_changed_callback* p) { p->release(); } });
     }
@@ -204,12 +204,9 @@ device::device(std::shared_ptr<context> ctx,
 
 device::~device()
 {
-    *_is_alive = false;
-
     if (_device_changed_notifications)
-    {
         _context->unregister_internal_device_callback(_callback_id);
-    }
+
     _sensors.clear();
 }
 
diff --git a/src/device.h b/src/device.h
index 3f7096bc387..eab39ec333a 100644
--- a/src/device.h
+++ b/src/device.h
@@ -73,8 +73,7 @@ class device : public virtual device_interface, public info_container
 
     bool is_valid() const override
     {
-        std::lock_guard<std::mutex> lock(_device_changed_mtx);
-        return _is_valid;
+        return *_is_alive;
     }
 
     void tag_profiles(stream_profiles profiles) const override;
@@ -104,12 +103,11 @@ class device : public virtual device_interface, public info_container
     std::vector<std::shared_ptr<sensor_interface>> _sensors;
     std::shared_ptr<context> _context;
     const platform::backend_device_group _group;
-    bool _is_valid, _device_changed_notifications;
-    mutable std::mutex _device_changed_mtx;
+    bool _device_changed_notifications;
     uint64_t _callback_id;
     lazy<std::vector<tagged_profile>> _profiles_tags;
 
-    std::shared_ptr< bool > _is_alive; // Ensures object can be accessed
+    std::shared_ptr< std::atomic< bool > > _is_alive;
 };
 
 // Helper function that should be used when multiple FW calls needs to be made.