kern: implement SvcCancelSynchronization

libraries/libmesosphere/include/mesosphere/kern_k_thread.hpp

@@ -390,6 +390,8 @@ namespace ams::kern {
                 return this->wait_result;
             }
 
+            void WaitCancel();
+
             bool IsWaitCancelled() const { return this->wait_cancelled; }
             void ClearWaitCancelled() { this->wait_cancelled = false; }
 

libraries/libmesosphere/source/kern_k_thread.cpp

@@ -439,6 +439,27 @@ namespace ams::kern {
         }
     }
 
+    void KThread::WaitCancel() {
+        MESOSPHERE_ASSERT_THIS();
+
+        KScopedSchedulerLock sl;
+
+        /* Check if we're waiting and cancellable. */
+        if (this->GetState() == ThreadState_Waiting && this->cancellable) {
+            if (this->sleeping_queue != nullptr) {
+                /* TODO: Cancel light IPC. */
+                MESOSPHERE_UNIMPLEMENTED();
+            } else {
+                this->SetSyncedObject(nullptr, svc::ResultCancelled());
+                this->SetState(ThreadState_Runnable);
+                this->wait_cancelled = false;
+            }
+        } else {
+            /* Otherwise, note that we cancelled a wait. */
+            this->wait_cancelled = true;
+        }
+    }
+
     void KThread::TrySuspend() {
         MESOSPHERE_ASSERT_THIS();
         MESOSPHERE_ASSERT(KScheduler::IsSchedulerLockedByCurrentThread());

libraries/libmesosphere/source/svc/kern_svc_synchronization.cpp

@@ -102,6 +102,16 @@ namespace ams::kern::svc {
             return ResultSuccess();
         }
 
+        Result CancelSynchronization(ams::svc::Handle handle) {
+            /* Get the thread from its handle. */
+            KScopedAutoObject thread = GetCurrentProcess().GetHandleTable().GetObject<KThread>(handle);
+            R_UNLESS(thread.IsNotNull(), svc::ResultInvalidHandle());
+
+            /* Cancel the thread's wait. */
+            thread->WaitCancel();
+            return ResultSuccess();
+        }
+
     }
 
     /* =============================    64 ABI    ============================= */
@@ -119,7 +129,7 @@ namespace ams::kern::svc {
     }
 
     Result CancelSynchronization64(ams::svc::Handle handle) {
-        MESOSPHERE_PANIC("Stubbed SvcCancelSynchronization64 was called.");
+        return CancelSynchronization(handle);
     }
 
     void SynchronizePreemptionState64() {
@@ -141,7 +151,7 @@ namespace ams::kern::svc {
     }
 
     Result CancelSynchronization64From32(ams::svc::Handle handle) {
-        MESOSPHERE_PANIC("Stubbed SvcCancelSynchronization64From32 was called.");
+        return CancelSynchronization(handle);
     }
 
     void SynchronizePreemptionState64From32() {