From 331fa1d00d5bd7fcd0389816e3ef356df32ff86e Mon Sep 17 00:00:00 2001
From: Michael Scire <SciresM@gmail.com>
Date: Wed, 2 Dec 2020 01:28:21 -0800
Subject: [PATCH] kern: update KConditionVariable to support new
 has_waiter_flag rules

---
 .../source/kern_k_condition_variable.cpp            | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/libraries/libmesosphere/source/kern_k_condition_variable.cpp b/libraries/libmesosphere/source/kern_k_condition_variable.cpp
index 56ffaf491..e86aaad29 100644
--- a/libraries/libmesosphere/source/kern_k_condition_variable.cpp
+++ b/libraries/libmesosphere/source/kern_k_condition_variable.cpp
@@ -194,6 +194,12 @@ namespace ams::kern {
                 target_thread->ClearConditionVariable();
                 ++num_waiters;
             }
+
+            /* If we have no waiters, clear the has waiter flag. */
+            if (it == this->tree.end() || it->GetConditionVariableKey() != cv_key) {
+                const u32 has_waiter_flag = 0;
+                WriteToUser(cv_key, std::addressof(has_waiter_flag));
+            }
         }
 
         /* Close threads in the array. */
@@ -244,6 +250,13 @@ namespace ams::kern {
                     next_owner_thread->Wakeup();
                 }
 
+                /* Write to the cv key. */
+                {
+                    const u32 has_waiter_flag = 1;
+                    WriteToUser(key, std::addressof(has_waiter_flag));
+                    cpu::DataMemoryBarrier();
+                }
+
                 /* Write the value to userspace. */
                 if (!WriteToUser(addr, std::addressof(next_value))) {
                     slp.CancelSleep();