libbinder: setMinSchedulerPolicy
This function on BBinder allows the minimum scheduling priority for
incoming binder transactions to be set by the binder driver. This
functionality was originally developed for libhwbinder and ported here.
The main difference from libhwbider is that invalid priority sets cause
an abort, whereas for libhwbinder, an error is returned. Unfortunately,
that error is frequently ignored, and since this reflects static
configuration, abort is considered a benefit.
Bug: 149933095
Test: binderLibTest
Change-Id: Ie93aebb09f4142cd66d841ca8b3ca39d1e0bb75e
diff --git a/libs/binder/Binder.cpp b/libs/binder/Binder.cpp
index e0fb543..6ca3b16 100644
--- a/libs/binder/Binder.cpp
+++ b/libs/binder/Binder.cpp
@@ -24,6 +24,7 @@
#include <binder/IShellCallback.h>
#include <binder/Parcel.h>
+#include <linux/sched.h>
#include <stdio.h>
namespace android {
@@ -133,6 +134,8 @@
// unlocked objects
bool mRequestingSid = false;
sp<IBinder> mExtension;
+ int mPolicy = SCHED_NORMAL;
+ int mPriority = 0;
// for below objects
Mutex mLock;
@@ -279,6 +282,47 @@
return e->mExtension;
}
+void BBinder::setMinSchedulerPolicy(int policy, int priority) {
+ switch (policy) {
+ case SCHED_NORMAL:
+ LOG_ALWAYS_FATAL_IF(priority < -20 || priority > 19, "Invalid priority for SCHED_NORMAL: %d", priority);
+ break;
+ case SCHED_RR:
+ case SCHED_FIFO:
+ LOG_ALWAYS_FATAL_IF(priority < 1 || priority > 99, "Invalid priority for sched %d: %d", policy, priority);
+ break;
+ default:
+ LOG_ALWAYS_FATAL("Unrecognized scheduling policy: %d", policy);
+ }
+
+ Extras* e = mExtras.load(std::memory_order_acquire);
+
+ if (e == nullptr) {
+ // Avoid allocations if called with default.
+ if (policy == SCHED_NORMAL && priority == 0) {
+ return;
+ }
+
+ e = getOrCreateExtras();
+ if (!e) return; // out of memory
+ }
+
+ e->mPolicy = policy;
+ e->mPriority = priority;
+}
+
+int BBinder::getMinSchedulerPolicy() {
+ Extras* e = mExtras.load(std::memory_order_acquire);
+ if (e == nullptr) return SCHED_NORMAL;
+ return e->mPolicy;
+}
+
+int BBinder::getMinSchedulerPriority() {
+ Extras* e = mExtras.load(std::memory_order_acquire);
+ if (e == nullptr) return 0;
+ return e->mPriority;
+}
+
pid_t BBinder::getDebugPid() {
return getpid();
}