SF: Clean up helpers for thread priority

Dedupe error logs and remove otherwise unused return values.

Bug: 342681202
Flag: EXEMPT refactor
Test: m surfaceflinger
Change-Id: I6f68b884c1409f73127c06ed3d091dcbd7bdc264

Author: Dominik Laskowski

services/surfaceflinger/SurfaceFlinger.cpp

@@ -1009,9 +1009,8 @@ void SurfaceFlinger::init() FTL_FAKE_GUARD(kMainThreadContext) {
     mPowerAdvisor->init();
 
     if (base::GetBoolProperty("service.sf.prime_shader_cache"s, true)) {
-        if (setSchedFifo(false) != NO_ERROR) {
-            ALOGW("Can't set SCHED_OTHER for primeCache");
-        }
+        constexpr const char* kWhence = "primeCache";
+        setSchedFifo(false, kWhence);
 
         mRenderEnginePrimeCacheFuture.callOnce([this] {
             renderengine::PrimeCacheConfig config;
@@ -1047,9 +1046,7 @@ void SurfaceFlinger::init() FTL_FAKE_GUARD(kMainThreadContext) {
             return getRenderEngine().primeCache(config);
         });
 
-        if (setSchedFifo(true) != NO_ERROR) {
-            ALOGW("Can't set SCHED_FIFO after primeCache");
-        }
+        setSchedFifo(true, kWhence);
     }
 
     // Avoid blocking the main thread on `init` to set properties.
@@ -5690,16 +5687,11 @@ void SurfaceFlinger::setPowerModeInternal(const sp<DisplayDevice>& display, hal:
         }
 
         if (displayId == mActiveDisplayId) {
-            // TODO(b/281692563): Merge the syscalls. For now, keep uclamp in a separate syscall and
-            // set it before SCHED_FIFO due to b/190237315.
-            if (setSchedAttr(true) != NO_ERROR) {
-                ALOGW("Failed to set uclamp.min after powering on active display: %s",
-                      strerror(errno));
-            }
-            if (setSchedFifo(true) != NO_ERROR) {
-                ALOGW("Failed to set SCHED_FIFO after powering on active display: %s",
-                      strerror(errno));
-            }
+            // TODO: b/281692563 - Merge the syscalls. For now, keep uclamp in a separate syscall
+            // and set it before SCHED_FIFO due to b/190237315.
+            constexpr const char* kWhence = "setPowerMode(ON)";
+            setSchedAttr(true, kWhence);
+            setSchedFifo(true, kWhence);
         }
 
         getHwComposer().setPowerMode(displayId, mode);
@@ -5726,14 +5718,9 @@ void SurfaceFlinger::setPowerModeInternal(const sp<DisplayDevice>& display, hal:
             if (const auto display = getActivatableDisplay()) {
                 onActiveDisplayChangedLocked(activeDisplay.get(), *display);
             } else {
-                if (setSchedFifo(false) != NO_ERROR) {
-                    ALOGW("Failed to set SCHED_OTHER after powering off active display: %s",
-                          strerror(errno));
-                }
-                if (setSchedAttr(false) != NO_ERROR) {
-                    ALOGW("Failed set uclamp.min after powering off active display: %s",
-                          strerror(errno));
-                }
+                constexpr const char* kWhence = "setPowerMode(OFF)";
+                setSchedFifo(false, kWhence);
+                setSchedAttr(false, kWhence);
 
                 if (currentModeNotDozeSuspend) {
                     if (!FlagManager::getInstance().multithreaded_present()) {
@@ -7196,7 +7183,7 @@ static status_t validateScreenshotPermissions(const CaptureArgs& captureArgs) {
     return PERMISSION_DENIED;
 }
 
-status_t SurfaceFlinger::setSchedFifo(bool enabled) {
+void SurfaceFlinger::setSchedFifo(bool enabled, const char* whence) {
     static constexpr int kFifoPriority = 2;
     static constexpr int kOtherPriority = 0;
 
@@ -7211,19 +7198,19 @@ status_t SurfaceFlinger::setSchedFifo(bool enabled) {
     }
 
     if (sched_setscheduler(0, sched_policy, &param) != 0) {
-        return -errno;
+        const char* kPolicy[] = {"SCHED_OTHER", "SCHED_FIFO"};
+        ALOGW("%s: Failed to set %s: %s", whence, kPolicy[sched_policy == SCHED_FIFO],
+              strerror(errno));
     }
-
-    return NO_ERROR;
 }
 
-status_t SurfaceFlinger::setSchedAttr(bool enabled) {
+void SurfaceFlinger::setSchedAttr(bool enabled, const char* whence) {
     static const unsigned int kUclampMin =
             base::GetUintProperty<unsigned int>("ro.surface_flinger.uclamp.min"s, 0U);
 
     if (!kUclampMin) {
         // uclamp.min set to 0 (default), skip setting
-        return NO_ERROR;
+        return;
     }
 
     sched_attr attr = {};
@@ -7234,10 +7221,9 @@ status_t SurfaceFlinger::setSchedAttr(bool enabled) {
     attr.sched_util_max = 1024;
 
     if (syscall(__NR_sched_setattr, 0, &attr, 0)) {
-        return -errno;
+        const char* kAction[] = {"disable", "enable"};
+        ALOGW("%s: Failed to %s uclamp.min: %s", whence, kAction[enabled], strerror(errno));
     }
-
-    return NO_ERROR;
 }
 
 namespace {

services/surfaceflinger/SurfaceFlinger.h

@@ -211,11 +211,9 @@ class SurfaceFlinger : public BnSurfaceComposer,
     SurfaceFlinger(surfaceflinger::Factory&, SkipInitializationTag) ANDROID_API;
     explicit SurfaceFlinger(surfaceflinger::Factory&) ANDROID_API;
 
-    // set main thread scheduling policy
-    static status_t setSchedFifo(bool enabled) ANDROID_API;
-
-    // set main thread scheduling attributes
-    static status_t setSchedAttr(bool enabled);
+    // Set scheduling policy and attributes of main thread.
+    static void setSchedFifo(bool enabled, const char* whence);
+    static void setSchedAttr(bool enabled, const char* whence);
 
     static char const* getServiceName() ANDROID_API { return "SurfaceFlinger"; }
 

services/surfaceflinger/main_surfaceflinger.cpp

@@ -77,7 +77,7 @@ static void startDisplayService() {
     }
 }
 
-int main(int, char**) {
+int main() {
     signal(SIGPIPE, SIG_IGN);
 
     hardware::configureRpcThreadpool(1 /* maxThreads */,
@@ -91,9 +91,7 @@ int main(int, char**) {
 
     // Set uclamp.min setting on all threads, maybe an overkill but we want
     // to cover important threads like RenderEngine.
-    if (SurfaceFlinger::setSchedAttr(true) != NO_ERROR) {
-        ALOGW("Failed to set uclamp.min during boot: %s", strerror(errno));
-    }
+    SurfaceFlinger::setSchedAttr(true, __func__);
 
     // The binder threadpool we start will inherit sched policy and priority
     // of (this) creating thread. We want the binder thread pool to have
@@ -160,14 +158,8 @@ int main(int, char**) {
 
     startDisplayService(); // dependency on SF getting registered above
 
-    if (SurfaceFlinger::setSchedFifo(true) != NO_ERROR) {
-        ALOGW("Failed to set SCHED_FIFO during boot: %s", strerror(errno));
-    }
-
-    // run surface flinger in this thread
+    SurfaceFlinger::setSchedFifo(true, __func__);
     flinger->run();
-
-    return 0;
 }
 
 // TODO(b/129481165): remove the #pragma below and fix conversion issues