commit 9e2a2cd3132eae959293e94d32f2ca85653a788e
author Roman Stratiienko <r.stratiienko@gmail.com> Wed Dec 28 20:47:29 2022 +0200
committer Roman Stratiienko <r.stratiienko@gmail.com> Wed Jan 04 16:30:40 2023 +0200
tree f0e006ae8d7f4f7111bb1742e480fd04d3dfce6d
parent f818d4c92c407cb6460c89ab06eceeed4f5aa468

drm_hwcomposer: Make main mutex recursive

It allows to remove redundant unlock/lock pair from the code,
and should make it a little bit more race-proof.

Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>

hwc2_device/hwc2_device.cpp

diff --git a/hwc2_device/hwc2_device.cpp b/hwc2_device/hwc2_device.cpp
index 87a7705..d4ee10d 100644
--- a/hwc2_device/hwc2_device.cpp
+++ b/hwc2_device/hwc2_device.cpp
@@ -63,7 +63,7 @@
 static T DeviceHook(hwc2_device_t *dev, Args... args) {
   ALOGV("Device hook: %s", GetFuncName(__PRETTY_FUNCTION__).c_str());
   DrmHwcTwo *hwc = ToDrmHwcTwo(dev);
-  const std::lock_guard<std::mutex> lock(hwc->GetResMan().GetMainLock());
+  const std::unique_lock lock(hwc->GetResMan().GetMainLock());
   return static_cast<T>(((*hwc).*func)(std::forward<Args>(args)...));
 }
 
@@ -73,7 +73,7 @@
   ALOGV("Display #%" PRIu64 " hook: %s", display_handle,
         GetFuncName(__PRETTY_FUNCTION__).c_str());
   DrmHwcTwo *hwc = ToDrmHwcTwo(dev);
-  const std::lock_guard<std::mutex> lock(hwc->GetResMan().GetMainLock());
+  const std::unique_lock lock(hwc->GetResMan().GetMainLock());
   auto *display = hwc->GetDisplay(display_handle);
   if (display == nullptr)
     return static_cast<int32_t>(HWC2::Error::BadDisplay);
@@ -87,7 +87,7 @@
   ALOGV("Display #%" PRIu64 " Layer: #%" PRIu64 " hook: %s", display_handle,
         layer_handle, GetFuncName(__PRETTY_FUNCTION__).c_str());
   DrmHwcTwo *hwc = ToDrmHwcTwo(dev);
-  const std::lock_guard<std::mutex> lock(hwc->GetResMan().GetMainLock());
+  const std::unique_lock lock(hwc->GetResMan().GetMainLock());
   auto *display = hwc->GetDisplay(display_handle);
   if (display == nullptr)
     return static_cast<int32_t>(HWC2::Error::BadDisplay);