Disable the DRM master hooks when EGLFS isn't used

app/masterhook.c

@@ -28,6 +28,9 @@
 #include <xf86drm.h>
 #include <xf86drmMode.h>
 
+// Used to turn off the hooks when Qt is not using EGLFS
+bool g_DisableDrmHooks = false;
+
 // We require SDL 2.0.15+ to hook because it supports sharing
 // the DRM FD with our code. This avoids having multiple DRM FDs
 // in flight at the same time which would significantly complicate
@@ -90,6 +93,10 @@ int drmModeSetCrtc(int fd, uint32_t crtcId, uint32_t bufferId,
     // Lookup the real libdrm function pointers if we haven't yet
     pthread_once(&s_InitDrmFunctions, lookupRealDrmFunctions);
 
+    if (g_DisableDrmHooks) {
+        return fn_drmModeSetCrtc(fd, crtcId, bufferId, x, y, connectors, count, mode);
+    }
+
     // Grab the first DRM Master FD that makes it in here. This will be the Qt
     // EGLFS backend's DRM FD, on which we will call drmDropMaster() later.
     if (g_QtDrmMasterFd == -1 && drmIsMaster(fd)) {
@@ -128,7 +135,7 @@ int drmModePageFlip(int fd, uint32_t crtc_id, uint32_t fb_id, uint32_t flags, vo
 
     // Call into the real thing
     int err = fn_drmModePageFlip(fd, crtc_id, fb_id, flags, user_data);
-    if (err == -EACCES && fd == g_QtDrmMasterFd) {
+    if (!g_DisableDrmHooks && err == -EACCES && fd == g_QtDrmMasterFd) {
         // If SDL took master from us, try to grab it back temporarily
         int oldMasterFd = takeMasterFromSdlFd();
         drmSetMaster(fd);
@@ -148,6 +155,10 @@ int drmModeAtomicCommit(int fd, drmModeAtomicReqPtr req,
     // Lookup the real libdrm function pointers if we haven't yet
     pthread_once(&s_InitDrmFunctions, lookupRealDrmFunctions);
 
+    if (g_DisableDrmHooks) {
+        return fn_drmModeAtomicCommit(fd, req, flags, user_data);
+    }
+
     // Grab the first DRM Master FD that makes it in here. This will be the Qt
     // EGLFS backend's DRM FD, on which we will call drmDropMaster() later.
     if (g_QtDrmMasterFd == -1 && drmIsMaster(fd)) {
@@ -210,6 +221,10 @@ int close(int fd)
     // Lookup the real libc functions if we haven't yet
     pthread_once(&s_InitLibCFunctions, lookupRealLibCFunctions);
 
+    if (g_DisableDrmHooks) {
+        return fn_close(fd);
+    }
+
     // Remove this entry from the SDL FD table
     bool lastSdlFd = removeSdlFd(fd);