bsd: Fix eventfd broken logic (#3647)

* bsd: Fix eventfd broken logic

This commit fix eventfd logic being broken.

The following changes were made:
- EventFd IPC definition had argument inverted
- EventFd events weren't fired correctly
- Poll logic was wrong and unfinished for eventfd
- Reintroduce workaround from #3385 but in a safer way, and spawn 4
  threads.

* ipc: Rework a bit for multithreads

* Clean up debug logs

* Make server thread yield when managed lock isn't availaible

* Fix replyTargetHandle not being added in the proper locking scope

* Simplify some scopes

* Address gdkchan's comments

* Revert IPC workaround for now

* Reintroduce the EventFileDescriptor workaround

1 files changed, 30 insertions, 10 deletions

diff --git a/Ryujinx.HLE/HOS/Services/Sockets/Bsd/Impl/EventFileDescriptor.cs b/Ryujinx.HLE/HOS/Services/Sockets/Bsd/Impl/EventFileDescriptor.cs
index 239e2434..f84e9b93 100644
--- a/Ryujinx.HLE/HOS/Services/Sockets/Bsd/Impl/EventFileDescriptor.cs
+++ b/Ryujinx.HLE/HOS/Services/Sockets/Bsd/Impl/EventFileDescriptor.cs
@@ -26,8 +26,9 @@ namespace Ryujinx.HLE.HOS.Services.Sockets.Bsd
             _value = value;
             _flags = flags;
 
-            WriteEvent = new ManualResetEvent(true);
-            ReadEvent = new ManualResetEvent(true);
+            WriteEvent = new ManualResetEvent(false);
+            ReadEvent = new ManualResetEvent(false);
+            UpdateEventStates();
         }
 
         public int Refcount { get; set; }
@@ -38,6 +39,25 @@ namespace Ryujinx.HLE.HOS.Services.Sockets.Bsd
             ReadEvent.Dispose();
         }
 
+        private void ResetEventStates()
+        {
+            WriteEvent.Reset();
+            ReadEvent.Reset();
+        }
+
+        private void UpdateEventStates()
+        {
+            if (_value > 0)
+            {
+                ReadEvent.Set();
+            }
+
+            if (_value != uint.MaxValue - 1)
+            {
+                WriteEvent.Set();
+            }
+        }
+
         public LinuxError Read(out int readSize, Span<byte> buffer)
         {
             if (buffer.Length < sizeof(ulong))
@@ -47,10 +67,10 @@ namespace Ryujinx.HLE.HOS.Services.Sockets.Bsd
                 return LinuxError.EINVAL;
             }
 
-            ReadEvent.Reset();
-
             lock (_lock)
             {
+                ResetEventStates();
+
                 ref ulong count = ref MemoryMarshal.Cast<byte, ulong>(buffer)[0];
 
                 if (_value == 0)
@@ -66,6 +86,7 @@ namespace Ryujinx.HLE.HOS.Services.Sockets.Bsd
                     {
                         readSize = 0;
 
+                        UpdateEventStates();
                         return LinuxError.EAGAIN;
                     }
                 }
@@ -85,8 +106,7 @@ namespace Ryujinx.HLE.HOS.Services.Sockets.Bsd
                     _value = 0;
                 }
 
-                ReadEvent.Set();
-
+                UpdateEventStates();
                 return LinuxError.SUCCESS;
             }
         }
@@ -100,10 +120,10 @@ namespace Ryujinx.HLE.HOS.Services.Sockets.Bsd
                 return LinuxError.EINVAL;
             }
 
-            WriteEvent.Reset();
-
             lock (_lock)
             {
+                ResetEventStates();
+
                 if (_value > _value + count)
                 {
                     if (Blocking)
@@ -114,6 +134,7 @@ namespace Ryujinx.HLE.HOS.Services.Sockets.Bsd
                     {
                         writeSize = 0;
 
+                        UpdateEventStates();
                         return LinuxError.EAGAIN;
                     }
                 }
@@ -123,8 +144,7 @@ namespace Ryujinx.HLE.HOS.Services.Sockets.Bsd
                 _value += count;
                 Monitor.Pulse(_lock);
 
-                WriteEvent.Set();
-
+                UpdateEventStates();
                 return LinuxError.SUCCESS;
             }
         }