Merge "Reduce race when connecting to an existing content provider." into nyc-dev

4 files changed, 55 insertions, 4 deletions

diff --git a/core/java/android/os/Process.java b/core/java/android/os/Process.java
index 4506f51fe38a..f664e70cf7be 100644
--- a/core/java/android/os/Process.java
+++ b/core/java/android/os/Process.java
@@ -1184,6 +1184,8 @@ public class Process {
     /** @hide */
     public static final int PROC_QUOTES = 0x400;
     /** @hide */
+    public static final int PROC_CHAR = 0x800;
+    /** @hide */
     public static final int PROC_OUT_STRING = 0x1000;
     /** @hide */
     public static final int PROC_OUT_LONG = 0x2000;
diff --git a/core/jni/android_util_Process.cpp b/core/jni/android_util_Process.cpp
index f7a5e8a07fc0..3d952b0f713f 100644
--- a/core/jni/android_util_Process.cpp
+++ b/core/jni/android_util_Process.cpp
@@ -832,6 +832,7 @@ enum {
     PROC_COMBINE = 0x100,
     PROC_PARENS = 0x200,
     PROC_QUOTES = 0x400,
+    PROC_CHAR = 0x800,
     PROC_OUT_STRING = 0x1000,
     PROC_OUT_LONG = 0x2000,
     PROC_OUT_FLOAT = 0x4000,
@@ -933,8 +934,13 @@ jboolean android_os_Process_parseProcLineArray(JNIEnv* env, jobject clazz,
                 floatsData[di] = strtof(buffer+start, &end);
             }
             if ((mode&PROC_OUT_LONG) != 0 && di < NL) {
-                char* end;
-                longsData[di] = strtoll(buffer+start, &end, 10);
+                if ((mode&PROC_CHAR) != 0) {
+                    // Caller wants single first character returned as one long.
+                    longsData[di] = buffer[start];
+                } else {
+                    char* end;
+                    longsData[di] = strtoll(buffer+start, &end, 10);
+                }
             }
             if ((mode&PROC_OUT_STRING) != 0 && di < NS) {
                 jstring str = env->NewStringUTF(buffer+start);
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 159a1bf89800..09a518553997 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -273,6 +273,10 @@ import static android.content.pm.PackageManager.MATCH_SYSTEM_ONLY;
 import static android.content.pm.PackageManager.MATCH_UNINSTALLED_PACKAGES;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.content.res.Configuration.UI_MODE_TYPE_TELEVISION;
+import static android.os.Process.PROC_CHAR;
+import static android.os.Process.PROC_OUT_LONG;
+import static android.os.Process.PROC_PARENS;
+import static android.os.Process.PROC_SPACE_TERM;
 import static android.provider.Settings.Global.ALWAYS_FINISH_ACTIVITIES;
 import static android.provider.Settings.Global.DEBUG_APP;
 import static android.provider.Settings.Global.DEVELOPMENT_ENABLE_FREEFORM_WINDOWS_SUPPORT;
@@ -6412,7 +6416,7 @@ public final class ActivityManagerService extends ActivityManagerNative
         EventLog.writeEvent(EventLogTags.AM_PROC_BOUND, app.userId, app.pid, app.processName);
 
         app.makeActive(thread, mProcessStats);
-        app.curAdj = app.setAdj = ProcessList.INVALID_ADJ;
+        app.curAdj = app.setAdj = app.verifiedAdj = ProcessList.INVALID_ADJ;
         app.curSchedGroup = app.setSchedGroup = ProcessList.SCHED_GROUP_DEFAULT;
         app.forcingToForeground = null;
         updateProcessForegroundLocked(app, false, false);
@@ -10535,6 +10539,30 @@ public final class ActivityManagerService extends ActivityManagerNative
         }
     }
 
+    private static final int[] PROCESS_STATE_STATS_FORMAT = new int[] {
+            PROC_SPACE_TERM,
+            PROC_SPACE_TERM|PROC_PARENS,
+            PROC_SPACE_TERM|PROC_CHAR|PROC_OUT_LONG,        // 3: process state
+    };
+
+    private final long[] mProcessStateStatsLongs = new long[1];
+
+    boolean isProcessAliveLocked(ProcessRecord proc) {
+        if (proc.procStatFile == null) {
+            proc.procStatFile = "/proc/" + proc.pid + "/stat";
+        }
+        mProcessStateStatsLongs[0] = 0;
+        if (!Process.readProcFile(proc.procStatFile, PROCESS_STATE_STATS_FORMAT, null,
+                mProcessStateStatsLongs, null)) {
+            if (DEBUG_OOM_ADJ) Slog.d(TAG, "UNABLE TO RETRIEVE STATE FOR " + proc.procStatFile);
+            return false;
+        }
+        final long state = mProcessStateStatsLongs[0];
+        if (DEBUG_OOM_ADJ) Slog.d(TAG, "RETRIEVED STATE FOR " + proc.procStatFile + ": "
+                + (char)state);
+        return state != 'Z' && state != 'X' && state != 'x' && state != 'K';
+    }
+
     private ContentProviderHolder getContentProviderImpl(IApplicationThread caller,
             String name, IBinder token, boolean stable, int userId) {
         ContentProviderRecord cpr;
@@ -10622,7 +10650,16 @@ public final class ActivityManagerService extends ActivityManagerNative
                 }
 
                 checkTime(startTime, "getContentProviderImpl: before updateOomAdj");
+                final int verifiedAdj = cpr.proc.verifiedAdj;
                 boolean success = updateOomAdjLocked(cpr.proc);
+                // XXX things have changed so updateOomAdjLocked doesn't actually tell us
+                // if the process has been successfully adjusted.  So to reduce races with
+                // it, we will check whether the process still exists.  Note that this doesn't
+                // completely get rid of races with LMK killing the process, but should make
+                // them much smaller.
+                if (success && verifiedAdj != cpr.proc.setAdj && !isProcessAliveLocked(cpr.proc)) {
+                    success = false;
+                }
                 maybeUpdateProviderUsageStatsLocked(r, cpr.info.packageName, name);
                 checkTime(startTime, "getContentProviderImpl: after updateOomAdj");
                 if (DEBUG_PROVIDER) Slog.i(TAG_PROVIDER, "Adjust success: " + success);
@@ -10648,6 +10685,8 @@ public final class ActivityManagerService extends ActivityManagerNative
                     }
                     providerRunning = false;
                     conn = null;
+                } else {
+                    cpr.proc.verifiedAdj = cpr.proc.setAdj;
                 }
 
                 Binder.restoreCallingIdentity(origId);
@@ -20082,6 +20121,7 @@ public final class ActivityManagerService extends ActivityManagerNative
                     "Set " + app.pid + " " + app.processName + " adj " + app.curAdj + ": "
                     + app.adjType);
             app.setAdj = app.curAdj;
+            app.verifiedAdj = ProcessList.INVALID_ADJ;
         }
 
         if (app.setSchedGroup != app.curSchedGroup) {
diff --git a/services/core/java/com/android/server/am/ProcessRecord.java b/services/core/java/com/android/server/am/ProcessRecord.java
index 691fd2abe0b3..8911a3e94979 100644
--- a/services/core/java/com/android/server/am/ProcessRecord.java
+++ b/services/core/java/com/android/server/am/ProcessRecord.java
@@ -75,6 +75,7 @@ final class ProcessRecord {
     ProcessState baseProcessTracker;
     BatteryStatsImpl.Uid.Proc curProcBatteryStats;
     int pid;                    // The process of this application; 0 if none
+    String procStatFile;        // path to /proc/<pid>/stat
     int[] gids;                 // The gids this process was launched with
     String requiredAbi;         // The ABI this process was launched with
     String instructionSet;      // The instruction set this process was launched with
@@ -93,6 +94,7 @@ final class ProcessRecord {
     int setRawAdj;              // Last set OOM unlimited adjustment for this process
     int curAdj;                 // Current OOM adjustment for this process
     int setAdj;                 // Last set OOM adjustment for this process
+    int verifiedAdj;            // The last adjustment that was verified as actually being set
     int curSchedGroup;          // Currently desired scheduling class
     int setSchedGroup;          // Last set to background scheduling class
     int trimMemoryLevel;        // Last selected memory trimming level
@@ -441,7 +443,7 @@ final class ProcessRecord {
         pkgList.put(_info.packageName, new ProcessStats.ProcessStateHolder(_info.versionCode));
         maxAdj = ProcessList.UNKNOWN_ADJ;
         curRawAdj = setRawAdj = ProcessList.INVALID_ADJ;
-        curAdj = setAdj = ProcessList.INVALID_ADJ;
+        curAdj = setAdj = verifiedAdj = ProcessList.INVALID_ADJ;
         persistent = false;
         removed = false;
         lastStateTime = lastPssTime = nextPssTime = SystemClock.uptimeMillis();
@@ -449,6 +451,7 @@ final class ProcessRecord {
 
     public void setPid(int _pid) {
         pid = _pid;
+        procStatFile = null;
         shortStringName = null;
         stringName = null;
     }