From fe0039091c21fb3fd99979a611da6519edbbe794 Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Wed, 28 Apr 2021 21:09:38 +0300
Subject: [PATCH] platforms/drm: Don't search for gpus on add udev event

If a gpu is added, don't search for it pointlessly in m_gpus.
---
 src/plugins/platforms/drm/drm_backend.cpp | 42 ++++++++++++++---------
 src/plugins/platforms/drm/drm_backend.h   |  1 +
 2 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/src/plugins/platforms/drm/drm_backend.cpp b/src/plugins/platforms/drm/drm_backend.cpp
index 6c3b94ea18..ce580636eb 100644
--- a/src/plugins/platforms/drm/drm_backend.cpp
+++ b/src/plugins/platforms/drm/drm_backend.cpp
@@ -236,13 +236,7 @@ void DrmBackend::handleUdevEvent()
         if (!session()->isActive()) {
             continue;
         }
-        DrmGpu *drmGpu = nullptr;
-        for (const auto &gpu : qAsConst(m_gpus)) {
-            if (gpu->drmId() == device->sysNum()) {
-                drmGpu = gpu;
-                break;
-            }
-        }
+
         if (device->action() == QStringLiteral("add")) {
             if (m_gpus.isEmpty() || !primaryGpu()->useEglStreams()) {
                 if (const auto &gpu = addGpu(std::move(device))) {
@@ -251,24 +245,28 @@ void DrmBackend::handleUdevEvent()
                     emit gpuAdded(gpu);
                 }
             }
-        } else if (drmGpu) {
-            if (device->action() == QStringLiteral("change")) {
-                qCDebug(KWIN_DRM) << "Received hot plug event for monitored drm device";
-                updateOutputs();
-                updateCursor();
-            } else if (device->action() == QStringLiteral("remove")) {
-                if (primaryGpu() == drmGpu) {
+        } else if (device->action() == QStringLiteral("remove")) {
+            DrmGpu *gpu = findGpu(device->sysNum());
+            if (gpu) {
+                if (primaryGpu() == gpu) {
                     qCCritical(KWIN_DRM) << "Primary gpu has been removed! Quitting...";
                     kwinApp()->quit();
                     return;
                 } else {
-                    emit gpuRemoved(drmGpu);
-                    m_gpus.removeOne(drmGpu);
-                    delete drmGpu;
+                    emit gpuRemoved(gpu);
+                    m_gpus.removeOne(gpu);
+                    delete gpu;
                     updateOutputs();
                     updateCursor();
                 }
             }
+        } else if (device->action() == QStringLiteral("change")) {
+            DrmGpu *gpu = findGpu(device->sysNum());
+            if (gpu) {
+                qCDebug(KWIN_DRM) << "Received hot plug event for monitored drm device";
+                updateOutputs();
+                updateCursor();
+            }
         }
     }
 }
@@ -675,4 +673,14 @@ DrmGpu *DrmBackend::primaryGpu() const
     return m_gpus.isEmpty() ? nullptr : m_gpus[0];
 }
 
+DrmGpu *DrmBackend::findGpu(int sysNum) const
+{
+    for (DrmGpu *gpu : qAsConst(m_gpus)) {
+        if (gpu->drmId() == sysNum) {
+            return gpu;
+        }
+    }
+    return nullptr;
+}
+
 }
diff --git a/src/plugins/platforms/drm/drm_backend.h b/src/plugins/platforms/drm/drm_backend.h
index 6fd6d68a96..d9223e31ec 100644
--- a/src/plugins/platforms/drm/drm_backend.h
+++ b/src/plugins/platforms/drm/drm_backend.h
@@ -64,6 +64,7 @@ public:
     QString supportInformation() const override;
 
     DrmGpu *primaryGpu() const;
+    DrmGpu *findGpu(int sysNum) const;
 
 public Q_SLOTS:
     void turnOutputsOn();