Scheduler: Add protections for Yield bombing

In case of redundant yields, the scheduler will now idle the core for 
it's timeslice, in order to avoid continuously yielding the same thing 
over and over.

1 files changed, 9 insertions, 7 deletions

diff --git a/src/core/hle/kernel/scheduler.cpp b/src/core/hle/kernel/scheduler.cpp
index df4e9b799..451fd8077 100644
--- a/src/core/hle/kernel/scheduler.cpp
+++ b/src/core/hle/kernel/scheduler.cpp
@@ -118,7 +118,7 @@ void GlobalScheduler::SelectThread(u32 core) {
  * YieldThread takes a thread and moves it to the back of the it's priority list
  * This operation can be redundant and no scheduling is changed if marked as so.
  */
-void GlobalScheduler::YieldThread(Thread* yielding_thread) {
+bool GlobalScheduler::YieldThread(Thread* yielding_thread) {
     // Note: caller should use critical section, etc.
     const u32 core_id = static_cast<u32>(yielding_thread->GetProcessorID());
     const u32 priority = yielding_thread->GetPriority();
@@ -129,7 +129,7 @@ void GlobalScheduler::YieldThread(Thread* yielding_thread) {
     scheduled_queue[core_id].yield(priority);
 
     Thread* winner = scheduled_queue[core_id].front(priority);
-    AskForReselectionOrMarkRedundant(yielding_thread, winner);
+    return AskForReselectionOrMarkRedundant(yielding_thread, winner);
 }
 
 /*
@@ -138,7 +138,7 @@ void GlobalScheduler::YieldThread(Thread* yielding_thread) {
  * a better priority than the next thread in the core.
  * This operation can be redundant and no scheduling is changed if marked as so.
  */
-void GlobalScheduler::YieldThreadAndBalanceLoad(Thread* yielding_thread) {
+bool GlobalScheduler::YieldThreadAndBalanceLoad(Thread* yielding_thread) {
     // Note: caller should check if !thread.IsSchedulerOperationRedundant and use critical section,
     // etc.
     const u32 core_id = static_cast<u32>(yielding_thread->GetProcessorID());
@@ -186,7 +186,7 @@ void GlobalScheduler::YieldThreadAndBalanceLoad(Thread* yielding_thread) {
         winner = next_thread;
     }
 
-    AskForReselectionOrMarkRedundant(yielding_thread, winner);
+    return AskForReselectionOrMarkRedundant(yielding_thread, winner);
 }
 
 /*
@@ -195,7 +195,7 @@ void GlobalScheduler::YieldThreadAndBalanceLoad(Thread* yielding_thread) {
  * a suggested thread is obtained instead.
  * This operation can be redundant and no scheduling is changed if marked as so.
  */
-void GlobalScheduler::YieldThreadAndWaitForLoadBalancing(Thread* yielding_thread) {
+bool GlobalScheduler::YieldThreadAndWaitForLoadBalancing(Thread* yielding_thread) {
     // Note: caller should check if !thread.IsSchedulerOperationRedundant and use critical section,
     // etc.
     Thread* winner = nullptr;
@@ -235,7 +235,7 @@ void GlobalScheduler::YieldThreadAndWaitForLoadBalancing(Thread* yielding_thread
         }
     }
 
-    AskForReselectionOrMarkRedundant(yielding_thread, winner);
+    return AskForReselectionOrMarkRedundant(yielding_thread, winner);
 }
 
 void GlobalScheduler::Schedule(u32 priority, u32 core, Thread* thread) {
@@ -248,13 +248,15 @@ void GlobalScheduler::SchedulePrepend(u32 priority, u32 core, Thread* thread) {
     scheduled_queue[core].add(thread, priority, false);
 }
 
-void GlobalScheduler::AskForReselectionOrMarkRedundant(Thread* current_thread, Thread* winner) {
+bool GlobalScheduler::AskForReselectionOrMarkRedundant(Thread* current_thread, Thread* winner) {
     if (current_thread == winner) {
         // TODO(blinkhawk): manage redundant operations, this is not implemented.
         // as its mostly an optimization.
         // current_thread->SetRedundantSchedulerOperation();
+        return true;
     } else {
         reselection_pending.store(true, std::memory_order_release);
+        return false;
     }
 }