drm_hwcomposer: Add refcount for GEM handle

The linux kernel doesn't provide reference counting for the handle
returned by FD_TO_HANDLE ioctl. It means that if the same Gralloc buffer
is imported twice, the first GEM_CLOSE will destroy the handle even if it
is still in use by another import.

Remedy this issue by doing the reference counting directly in the DRM
generic platform support: ImportHandle() will increase the reference,
while ReleaseHandle() will decrease and close it, if necessary.

Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>

6 files changed, 46 insertions, 7 deletions

diff --git a/platform/platformdrmgeneric.cpp b/platform/platformdrmgeneric.cpp
index 0883b90..668742c 100644
--- a/platform/platformdrmgeneric.cpp
+++ b/platform/platformdrmgeneric.cpp
@@ -143,6 +143,8 @@ int DrmGenericImporter::ImportBuffer(buffer_handle_t handle, hwc_drm_bo_t *bo) {
     return ret;
   }
 
+  ImportHandle(gem_handle);
+
   return ret;
 }
 
@@ -151,17 +153,12 @@ int DrmGenericImporter::ReleaseBuffer(hwc_drm_bo_t *bo) {
     if (drmModeRmFB(drm_->fd(), bo->fb_id))
       ALOGE("Failed to rm fb");
 
-  struct drm_gem_close gem_close;
-  memset(&gem_close, 0, sizeof(gem_close));
-
   for (int i = 0; i < HWC_DRM_BO_MAX_PLANES; i++) {
     if (!bo->gem_handles[i])
       continue;
 
-    gem_close.handle = bo->gem_handles[i];
-    int ret = drmIoctl(drm_->fd(), DRM_IOCTL_GEM_CLOSE, &gem_close);
-    if (ret) {
-      ALOGE("Failed to close gem handle %d %d", i, ret);
+    if (ReleaseHandle(bo->gem_handles[i])) {
+      ALOGE("Failed to release gem handle %d", bo->gem_handles[i]);
     } else {
       for (int j = i + 1; j < HWC_DRM_BO_MAX_PLANES; j++)
         if (bo->gem_handles[j] == bo->gem_handles[i])
@@ -191,4 +188,32 @@ std::unique_ptr<Planner> Planner::CreateInstance(DrmDevice *) {
   return planner;
 }
 #endif
+
+int DrmGenericImporter::ImportHandle(uint32_t gem_handle) {
+  gem_refcount_[gem_handle]++;
+
+  return 0;
+}
+
+int DrmGenericImporter::ReleaseHandle(uint32_t gem_handle) {
+  if (--gem_refcount_[gem_handle])
+    return 0;
+
+  gem_refcount_.erase(gem_handle);
+
+  return CloseHandle(gem_handle);
+}
+
+int DrmGenericImporter::CloseHandle(uint32_t gem_handle) {
+  struct drm_gem_close gem_close;
+
+  memset(&gem_close, 0, sizeof(gem_close));
+
+  gem_close.handle = gem_handle;
+  int ret = drmIoctl(drm_->fd(), DRM_IOCTL_GEM_CLOSE, &gem_close);
+  if (ret)
+    ALOGE("Failed to close gem handle %d %d", gem_handle, ret);
+
+  return ret;
+}
 }
diff --git a/platform/platformdrmgeneric.h b/platform/platformdrmgeneric.h
index 7bb2ea2..a7cf941 100644
--- a/platform/platformdrmgeneric.h
+++ b/platform/platformdrmgeneric.h
@@ -21,6 +21,7 @@
 #include "platform.h"
 
 #include <hardware/gralloc.h>
+#include <map>
 
 #include <drm/drm_fourcc.h>
 
@@ -40,6 +41,8 @@ class DrmGenericImporter : public Importer {
   int ImportBuffer(buffer_handle_t handle, hwc_drm_bo_t *bo) override;
   int ReleaseBuffer(hwc_drm_bo_t *bo) override;
   bool CanImportBuffer(buffer_handle_t handle) override;
+  int ImportHandle(uint32_t gem_handle);
+  int ReleaseHandle(uint32_t gem_handle);
 
   uint32_t ConvertHalFormatToDrm(uint32_t hal_format);
   uint32_t DrmFormatToBitsPerPixel(uint32_t drm_format);
@@ -50,6 +53,9 @@ class DrmGenericImporter : public Importer {
  private:
   const gralloc_module_t *gralloc_;
   bool exclude_non_hwfb_;
+
+  int CloseHandle(uint32_t gem_handle);
+  std::map<uint32_t, int> gem_refcount_;
 };
 }  // namespace android
 
diff --git a/platform/platformhisi.cpp b/platform/platformhisi.cpp
index 2e6ac43..81d8039 100644
--- a/platform/platformhisi.cpp
+++ b/platform/platformhisi.cpp
@@ -173,6 +173,8 @@ int HisiImporter::ImportBuffer(buffer_handle_t handle, hwc_drm_bo_t *bo) {
     return ret;
   }
 
+  ImportHandle(gem_handle);
+
   return ret;
 }
 
diff --git a/platform/platformimagination.cpp b/platform/platformimagination.cpp
index 565e6ee..5e0335c 100644
--- a/platform/platformimagination.cpp
+++ b/platform/platformimagination.cpp
@@ -69,6 +69,8 @@ int ImaginationImporter::ImportBuffer(buffer_handle_t handle,
     return ret;
   }
 
+  ImportHandle(gem_handle);
+
   return 0;
 }
 
diff --git a/platform/platformmeson.cpp b/platform/platformmeson.cpp
index 5184972..7b7a1f1 100644
--- a/platform/platformmeson.cpp
+++ b/platform/platformmeson.cpp
@@ -123,6 +123,8 @@ int MesonImporter::ImportBuffer(buffer_handle_t handle, hwc_drm_bo_t *bo) {
     return ret;
   }
 
+  ImportHandle(gem_handle);
+
   return ret;
 }
 
diff --git a/platform/platformminigbm.cpp b/platform/platformminigbm.cpp
index a65e196..cb1e110 100644
--- a/platform/platformminigbm.cpp
+++ b/platform/platformminigbm.cpp
@@ -74,6 +74,8 @@ int DrmMinigbmImporter::ImportBuffer(buffer_handle_t handle, hwc_drm_bo_t *bo) {
     return ret;
   }
 
+  ImportHandle(gem_handle);
+
   return ret;
 }