Watchdog now records kernel stacks when it fires

The kernel threads are appended to the usual /data/anr/traces.txt file
and dropboxed along with the usual Dalvik stack dumps.

Change-Id: I120f1f5ee54c965efe9ac0c7f40fdef56385f1fa
NOTE: this change depends on the kernel publishing /proc/$PID/stack

1 files changed, 111 insertions, 0 deletions

diff --git a/core/jni/android_server_Watchdog.cpp b/core/jni/android_server_Watchdog.cpp
new file mode 100644
index 0000000..2a90db7
--- /dev/null
+++ b/core/jni/android_server_Watchdog.cpp
@@ -0,0 +1,111 @@
+/*
+ ** Copyright 2010, The Android Open Source Project
+ **
+ ** Licensed under the Apache License, Version 2.0 (the "License");
+ ** you may not use this file except in compliance with the License.
+ ** You may obtain a copy of the License at
+ **
+ **     http://www.apache.org/licenses/LICENSE-2.0
+ **
+ ** Unless required by applicable law or agreed to in writing, software
+ ** distributed under the License is distributed on an "AS IS" BASIS,
+ ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ ** See the License for the specific language governing permissions and
+ ** limitations under the License.
+ */
+
+#define LOG_TAG "Watchdog_N"
+#include <utils/Log.h>
+
+#include <sys/types.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <string.h>
+#include <errno.h>
+
+#include "jni.h"
+#include "JNIHelp.h"
+#include <android_runtime/AndroidRuntime.h>
+
+static void dumpOneStack(int tid, int outFd) {
+    char buf[64];
+
+    snprintf(buf, sizeof(buf), "/proc/%d/stack", tid);
+    int stackFd = open(buf, O_RDONLY);
+    if (stackFd >= 0) {
+        // header for readability
+        strncat(buf, ":\n", sizeof(buf) - strlen(buf) - 1);
+        write(outFd, buf, strlen(buf));
+
+        // copy the stack dump text
+        int nBytes;
+        while ((nBytes = read(stackFd, buf, sizeof(buf))) > 0) {
+            write(outFd, buf, nBytes);
+        }
+
+        // footer and done
+        write(outFd, "\n", 1);
+        close(stackFd);
+    } else {
+        LOGE("Unable to open stack of tid %d : %d (%s)", tid, errno, strerror(errno));
+    }
+}
+
+static void dumpKernelStacks(JNIEnv* env, jobject clazz, jstring pathStr) {
+    char buf[128];
+    DIR* taskdir;
+
+    LOGI("dumpKernelStacks");
+    if (!pathStr) {
+        jniThrowException(env, "java/lang/IllegalArgumentException", "Null path");
+        return;
+    }
+
+    const char *path = env->GetStringUTFChars(pathStr, NULL);
+
+    int outFd = open(path, O_WRONLY | O_APPEND | O_CREAT);
+    if (outFd < 0) {
+        LOGE("Unable to open stack dump file: %d (%s)", errno, strerror(errno));
+        goto done;
+    }
+
+    snprintf(buf, sizeof(buf), "\n----- begin pid %d kernel stacks -----\n", getpid());
+    write(outFd, buf, strlen(buf));
+
+    // look up the list of all threads in this process
+    snprintf(buf, sizeof(buf), "/proc/%d/task", getpid());
+    taskdir = opendir(buf);
+    if (taskdir != NULL) {
+        struct dirent * ent;
+        while ((ent = readdir(taskdir)) != NULL) {
+            int tid = atoi(ent->d_name);
+            if (tid > 0 && tid <= 65535) {
+                // dump each stack trace
+                dumpOneStack(tid, outFd);
+            }
+        }
+        closedir(taskdir);
+    }
+
+    snprintf(buf, sizeof(buf), "----- end pid %d kernel stacks -----\n", getpid());
+    write(outFd, buf, strlen(buf));
+
+    close(outFd);
+done:
+    env->ReleaseStringUTFChars(pathStr, path);
+}
+
+// ----------------------------------------
+
+namespace android {
+
+static const JNINativeMethod g_methods[] = {
+    { "native_dumpKernelStacks", "(Ljava/lang/String;)V", (void*)dumpKernelStacks },
+};
+
+int register_android_server_Watchdog(JNIEnv* env) {
+    return AndroidRuntime::registerNativeMethods(env, "com/android/server/Watchdog",
+                                                 g_methods, NELEM(g_methods));
+}
+
+}