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Commit 6d0dd1a2 authored by wangmingming1's avatar wangmingming1 Committed by Elliott Hughes
Browse files

zygote: use async signal safe log to record child process death 

Bug: https://issuetracker.google.com/issues/119713191


Test: open/close apps, observe the child process death log
Test: run monkey
Change-Id: Ia121f44c00f715367446dfe97de6df1f7fa6bdfe
Signed-off-by: default avatarwangmingming1 <wangmingming1@xiaomi.com>
parent 0b3cef86

core/jni/Android.bp

+2 −1
Original line number Diff line number Diff line
@@ -225,6 +225,7 @@ cc_library_shared { 
    ],



    static_libs: [

        "libasync_safe",

        "libgif",

        "libseccomp_policy",

        "libgrallocusage",

core/jni/com_android_internal_os_Zygote.cpp

+16 −15
Original line number Diff line number Diff line
@@ -25,6 +25,8 @@ 


#define LOG_TAG "Zygote"



#include <async_safe/log.h>



// sys/mount.h has to come before linux/fs.h due to redefinition of MS_RDONLY, MS_BIND, etc

#include <sys/mount.h>

#include <linux/fs.h>
@@ -296,27 +298,23 @@ static void SigChldHandler(int /*signal_number*/) { 
  int saved_errno = errno;



  while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {

     // Log process-death status that we care about.  In general it is

     // not safe to call LOG(...) from a signal handler because of

     // possible reentrancy.  However, we know a priori that the

     // current implementation of LOG() is safe to call from a SIGCHLD

     // handler in the zygote process.  If the LOG() implementation

     // changes its locking strategy or its use of syscalls within the

     // lazy-init critical section, its use here may become unsafe.

     // Log process-death status that we care about.

    if (WIFEXITED(status)) {

      ALOGI("Process %d exited cleanly (%d)", pid, WEXITSTATUS(status));

      async_safe_format_log(ANDROID_LOG_INFO, LOG_TAG,

                            "Process %d exited cleanly (%d)", pid, WEXITSTATUS(status));

    } else if (WIFSIGNALED(status)) {

      ALOGI("Process %d exited due to signal (%d)", pid, WTERMSIG(status));

      if (WCOREDUMP(status)) {

        ALOGI("Process %d dumped core.", pid);

      }

      async_safe_format_log(ANDROID_LOG_INFO, LOG_TAG,

                            "Process %d exited due to signal %d (%s)%s", pid,

                            WTERMSIG(status), strsignal(WTERMSIG(status)),

                            WCOREDUMP(status) ? "; core dumped" : "");

    }



    // If the just-crashed process is the system_server, bring down zygote

    // so that it is restarted by init and system server will be restarted

    // from there.

    if (pid == gSystemServerPid) {

      ALOGE("Exit zygote because system server (%d) has terminated", pid);

      async_safe_format_log(ANDROID_LOG_ERROR, LOG_TAG,

                            "Exit zygote because system server (pid %d) has terminated", pid);

      kill(getpid(), SIGKILL);

    }
@@ -329,14 +327,17 @@ static void SigChldHandler(int /*signal_number*/) { 
  // Note that we shouldn't consider ECHILD an error because

  // the secondary zygote might have no children left to wait for.

  if (pid < 0 && errno != ECHILD) {

    ALOGW("Zygote SIGCHLD error in waitpid: %s", strerror(errno));

    async_safe_format_log(ANDROID_LOG_WARN, LOG_TAG,

                          "Zygote SIGCHLD error in waitpid: %s", strerror(errno));

  }



  if (blastulas_removed > 0) {

    if (write(gBlastulaPoolEventFD, &blastulas_removed, sizeof(blastulas_removed)) == -1) {

      // If this write fails something went terribly wrong.  We will now kill

      // the zygote and let the system bring it back up.

      ALOGE("Zygote failed to write to blastula pool event FD: %s", strerror(errno));

      async_safe_format_log(ANDROID_LOG_ERROR, LOG_TAG,

                            "Zygote failed to write to blastula pool event FD: %s",

                            strerror(errno));

      kill(getpid(), SIGKILL);

    }

  }