From 92726372f46162105ebea3b265d4e794c11281f0 Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Mon, 7 Jun 2021 11:11:30 +0200
Subject: [PATCH] platforms/drm: simplify deleted output handling

---
 src/plugins/platforms/drm/drm_backend.cpp | 10 ++++++
 src/plugins/platforms/drm/drm_backend.h   |  1 +
 src/plugins/platforms/drm/drm_gpu.cpp     | 27 ++++++++++++----
 src/plugins/platforms/drm/drm_output.cpp  | 39 +++++------------------
 src/plugins/platforms/drm/drm_output.h    |  3 --
 5 files changed, 39 insertions(+), 41 deletions(-)

diff --git a/src/plugins/platforms/drm/drm_backend.cpp b/src/plugins/platforms/drm/drm_backend.cpp
index 0a9a102720..135072c820 100644
--- a/src/plugins/platforms/drm/drm_backend.cpp
+++ b/src/plugins/platforms/drm/drm_backend.cpp
@@ -687,4 +687,14 @@ DrmGpu *DrmBackend::findGpu(dev_t deviceId) const
     return nullptr;
 }
 
+DrmGpu *DrmBackend::findGpuByFd(int fd) const
+{
+    for (DrmGpu *gpu : qAsConst(m_gpus)) {
+        if (gpu->fd() == fd) {
+            return gpu;
+        }
+    }
+    return nullptr;
+}
+
 }
diff --git a/src/plugins/platforms/drm/drm_backend.h b/src/plugins/platforms/drm/drm_backend.h
index f636e2542d..0e6d6df90d 100644
--- a/src/plugins/platforms/drm/drm_backend.h
+++ b/src/plugins/platforms/drm/drm_backend.h
@@ -64,6 +64,7 @@ public:
 
     DrmGpu *primaryGpu() const;
     DrmGpu *findGpu(dev_t deviceId) const;
+    DrmGpu *findGpuByFd(int fd) const;
 
 public Q_SLOTS:
     void turnOutputsOn();
diff --git a/src/plugins/platforms/drm/drm_gpu.cpp b/src/plugins/platforms/drm/drm_gpu.cpp
index e080ad8653..bcb1ec38b3 100644
--- a/src/plugins/platforms/drm/drm_gpu.cpp
+++ b/src/plugins/platforms/drm/drm_gpu.cpp
@@ -17,6 +17,7 @@
 #include "logging.h"
 #include "session.h"
 #include "renderloop_p.h"
+#include "main.h"
 
 #if HAVE_GBM
 #include "egl_gbm_backend.h"
@@ -390,7 +391,19 @@ static void pageFlipHandler(int fd, unsigned int frame, unsigned int sec, unsign
     Q_UNUSED(fd)
     Q_UNUSED(frame)
 
+    auto backend = dynamic_cast<DrmBackend*>(kwinApp()->platform());
+    if (!backend) {
+        return;
+    }
+    auto gpu = backend->findGpuByFd(fd);
+    if (!gpu) {
+        return;
+    }
     auto output = static_cast<DrmOutput *>(data);
+    if (!gpu->outputs().contains(output)) {
+        // output already got deleted
+        return;
+    }
 
     // The static_cast<> here are for a 32-bit environment where 
     // sizeof(time_t) == sizeof(unsigned int) == 4 . Putting @p sec
@@ -426,13 +439,13 @@ void DrmGpu::removeOutput(DrmOutput *output)
 {
     m_outputs.removeOne(output);
     Q_EMIT outputRemoved(output);
-    output->teardown();
-    output->m_crtc = nullptr;
-    m_connectors.removeOne(output->m_conn);
-    delete output->m_conn;
-    output->m_conn = nullptr;
-    if (output->m_primaryPlane) {
-        m_unusedPlanes << output->m_primaryPlane;
+    auto connector = output->m_conn;
+    auto primary = output->m_primaryPlane;
+    delete output;
+    m_connectors.removeOne(connector);
+    delete connector;
+    if (primary) {
+        m_unusedPlanes << primary;
     }
 }
 
diff --git a/src/plugins/platforms/drm/drm_output.cpp b/src/plugins/platforms/drm/drm_output.cpp
index 78d1f9dc00..ccb111f3db 100644
--- a/src/plugins/platforms/drm/drm_output.cpp
+++ b/src/plugins/platforms/drm/drm_output.cpp
@@ -49,21 +49,6 @@ DrmOutput::DrmOutput(DrmBackend *backend, DrmGpu *gpu)
 
 DrmOutput::~DrmOutput()
 {
-    Q_ASSERT(!m_pageFlipPending);
-    teardown();
-}
-
-RenderLoop *DrmOutput::renderLoop() const
-{
-    return m_renderLoop;
-}
-
-void DrmOutput::teardown()
-{
-    if (m_deleted) {
-        return;
-    }
-    m_deleted = true;
     hideCursor();
     m_crtc->blank(this);
 
@@ -74,10 +59,14 @@ void DrmOutput::teardown()
 
     m_cursor[0].reset(nullptr);
     m_cursor[1].reset(nullptr);
-    if (!m_pageFlipPending) {
-        deleteLater();
-    } //else will be deleted in the page flip handler
-    //this is needed so that the pageflipcallback handle isn't deleted
+    if (m_pageFlipPending) {
+        pageFlipped();
+    }
+}
+
+RenderLoop *DrmOutput::renderLoop() const
+{
+    return m_renderLoop;
 }
 
 bool DrmOutput::hideCursor()
@@ -105,10 +94,6 @@ bool DrmOutput::showCursor(DrmDumbBuffer *c)
 
 bool DrmOutput::showCursor()
 {
-    if (m_deleted) {
-        return false;
-    }
-
     const bool ret = showCursor(m_cursor[m_cursorIndex].data());
     if (!ret) {
         qCDebug(KWIN_DRM) << "DrmOutput::showCursor(DrmDumbBuffer) failed";
@@ -141,9 +126,6 @@ static bool isCursorSpriteCompatible(const QImage *buffer, const QImage *sprite)
 
 bool DrmOutput::updateCursor()
 {
-    if (m_deleted) {
-        return false;
-    }
     const Cursor *cursor = Cursors::self()->currentCursor();
     const QImage cursorImage = cursor->image();
     if (cursorImage.isNull()) {
@@ -526,11 +508,6 @@ void DrmOutput::pageFlipped()
     Q_ASSERT(m_pageFlipPending || !m_gpu->atomicModeSetting());
     m_pageFlipPending = false;
 
-    if (m_deleted) {
-        deleteLater();
-        return;
-    }
-
     if (!m_crtc) {
         return;
     }
diff --git a/src/plugins/platforms/drm/drm_output.h b/src/plugins/platforms/drm/drm_output.h
index 24380519c1..3b02fac50a 100644
--- a/src/plugins/platforms/drm/drm_output.h
+++ b/src/plugins/platforms/drm/drm_output.h
@@ -42,8 +42,6 @@ public:
 
     RenderLoop *renderLoop() const override;
 
-    ///queues deleting the output after a page flip has completed.
-    void teardown();
     bool showCursor(DrmDumbBuffer *buffer);
     bool showCursor();
     bool hideCursor();
@@ -161,7 +159,6 @@ private:
     QScopedPointer<DrmDumbBuffer> m_cursor[2];
     int m_cursorIndex = 0;
     bool m_hasNewCursor = false;
-    bool m_deleted = false;
     QTimer m_turnOffTimer;
 };