adb: don't spew to logcat when tracing is enabled.

When persist.adb.trace_mask is used to enable verbose logging, avoid
exponential logging when a user runs `adb logcat`. As a side-effect,
set the minimum logging level to include everything when ADB_TRACE is
used on the client (which is something we want anyway).

Bug: http://b/72971016
Test: `adb shell 'setprop persist.adb.trace_mask; killall adbd'; adb logcat`
Change-Id: Id4bca1f3933a920345499dbeaeb103c8a2e220cd

adb/adb_trace.cpp

@@ -42,7 +42,11 @@ void AdbLogger(android::base::LogId id, android::base::LogSeverity severity,
                const char* message) {
     android::base::StderrLogger(id, severity, tag, file, line, message);
 #if !ADB_HOST
-    gLogdLogger(id, severity, tag, file, line, message);
+    // Only print logs of INFO or higher to logcat, so that `adb logcat` with adbd tracing on
+    // doesn't result in exponential logging.
+    if (severity >= android::base::INFO) {
+        gLogdLogger(id, severity, tag, file, line, message);
+    }
 #endif
 }
 
@@ -137,11 +141,15 @@ static void setup_trace_mask() {
             // -1 is used for the special values "1" and "all" that enable all
             // tracing.
             adb_trace_mask = ~0;
-            return;
+            break;
         } else {
             adb_trace_mask |= 1 << flag->second;
         }
     }
+
+    if (adb_trace_mask != 0) {
+        android::base::SetMinimumLogSeverity(android::base::VERBOSE);
+    }
 }
 
 void adb_trace_init(char** argv) {

adb/adb_trace.h

@@ -43,11 +43,11 @@ enum AdbTrace {
 #define VLOG_IS_ON(TAG) \
     ((adb_trace_mask & (1 << (TAG))) != 0)
 
-#define VLOG(TAG)         \
+#define VLOG(TAG)                 \
     if (LIKELY(!VLOG_IS_ON(TAG))) \
-        ;                 \
-    else                  \
-        LOG(INFO)
+        ;                         \
+    else                          \
+        LOG(DEBUG)
 
 // You must define TRACE_TAG before using this macro.
 #define D(...) \