jdk8-mips64-public/hotspot: src/os/bsd/vm/jsig.c@79841fc03469 (annotated)

src/os/bsd/vm/jsig.c@79841fc03469 (annotated)

src/os/bsd/vm/jsig.c

Thu, 02 Jul 2015 07:30:09 -0700

author: dbuck
date: Thu, 02 Jul 2015 07:30:09 -0700
changeset 8034: 79841fc03469
parent 0: f90c822e73f8
permissions: -rw-r--r--

8072147: Preloading libjsig.dylib causes deadlock when signal() is called
Summary: Added check to prevent reentry of signal chaining code
Reviewed-by: dcubed, acorn, dholmes

 /*
  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 /* CopyrightVersion 1.2 */
 /* This is a special library that should be loaded before libc &
  * libthread to interpose the signal handler installation functions:
  * sigaction(), signal(), sigset().
  * Used for signal-chaining. See RFE 4381843.
  */
 #include <signal.h>
 #include <dlfcn.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
 #include <string.h>
 #define MAXSIGNUM 32
 #define MASK(sig) ((unsigned int)1 << sig)
 static struct sigaction sact[MAXSIGNUM]; /* saved signal handlers */
 static unsigned int jvmsigs = 0; /* signals used by jvm */
 static pthread_key_t reentry_flag_key;
 static pthread_once_t reentry_key_init_once = PTHREAD_ONCE_INIT;
 /* used to synchronize the installation of signal handlers */
 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
 static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 static pthread_t tid = 0;
 typedef void (*sa_handler_t)(int);
 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
 typedef sa_handler_t (*signal_t)(int, sa_handler_t);
 typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *);
 static signal_t os_signal = 0; /* os's version of signal()/sigset() */
 static sigaction_t os_sigaction = 0; /* os's version of sigaction() */
 static bool jvm_signal_installing = false;
 static bool jvm_signal_installed = false;
 #define check_status(cmd) \
   do { \
     int status = (cmd); \
     if (status != 0) { \
       printf("error %s (%d) in " #cmd "\n", strerror(status), status); \
       exit(1); \
     } \
   } while (0)
 static void signal_lock() {
   pthread_mutex_lock(&mutex);
   /* When the jvm is installing its set of signal handlers, threads
    * other than the jvm thread should wait */
   if (jvm_signal_installing) {
     if (tid != pthread_self()) {
       pthread_cond_wait(&cond, &mutex);
     }
   }
 }
 static void signal_unlock() {
   pthread_mutex_unlock(&mutex);
 }
 static void reentry_tls_init() {
     // value for reentry_flag_key will default to NULL (false)
     check_status(pthread_key_create(&reentry_flag_key, NULL));
 }
 static sa_handler_t call_os_signal(int sig, sa_handler_t disp,
                                    bool is_sigset) {
   sa_handler_t res;
   if (os_signal == NULL) {
     if (!is_sigset) {
       os_signal = (signal_t)dlsym(RTLD_NEXT, "signal");
     } else {
       os_signal = (signal_t)dlsym(RTLD_NEXT, "sigset");
     }
     if (os_signal == NULL) {
       printf("%s\n", dlerror());
       exit(0);
     }
   }
   check_status(pthread_once(&reentry_key_init_once, reentry_tls_init));
   // set reentry_flag_key to non-NULL to show reentry
   check_status(pthread_setspecific(reentry_flag_key, &res));
   res = (*os_signal)(sig, disp);
   check_status(pthread_setspecific(reentry_flag_key, NULL));
   return res;
 }
 static void save_signal_handler(int sig, sa_handler_t disp) {
   sigset_t set;
   sact[sig].sa_handler = disp;
   sigemptyset(&set);
   sact[sig].sa_mask = set;
   sact[sig].sa_flags = 0;
 }
 static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) {
   sa_handler_t oldhandler;
   bool sigused;
   signal_lock();
   sigused = (MASK(sig) & jvmsigs) != 0;
   if (jvm_signal_installed && sigused) {
     /* jvm has installed its signal handler for this signal. */
     /* Save the handler. Don't really install it. */
     oldhandler = sact[sig].sa_handler;
     save_signal_handler(sig, disp);
     signal_unlock();
     return oldhandler;
   } else if (jvm_signal_installing) {
     /* jvm is installing its signal handlers. Install the new
      * handlers and save the old ones. jvm uses sigaction().
      * Leave the piece here just in case. */
     oldhandler = call_os_signal(sig, disp, is_sigset);
     save_signal_handler(sig, oldhandler);
     /* Record the signals used by jvm */
     jvmsigs |= MASK(sig);
     signal_unlock();
     return oldhandler;
   } else {
     /* jvm has no relation with this signal (yet). Install the
      * the handler. */
     oldhandler = call_os_signal(sig, disp, is_sigset);
     signal_unlock();
     return oldhandler;
   }
 }
 sa_handler_t signal(int sig, sa_handler_t disp) {
   return set_signal(sig, disp, false);
 }
 sa_handler_t sigset(int sig, sa_handler_t disp) {
   printf("sigset() is not supported by BSD");
   exit(0);
  }
 static int call_os_sigaction(int sig, const struct sigaction  *act,
                              struct sigaction *oact) {
   if (os_sigaction == NULL) {
     os_sigaction = (sigaction_t)dlsym(RTLD_NEXT, "sigaction");
     if (os_sigaction == NULL) {
       printf("%s\n", dlerror());
       exit(0);
     }
   }
   return (*os_sigaction)(sig, act, oact);
 }
 int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) {
   int res;
   bool sigused;
   struct sigaction oldAct;
   check_status(pthread_once(&reentry_key_init_once, reentry_tls_init));
   if (pthread_getspecific(reentry_flag_key) != NULL) {
     return call_os_sigaction(sig, act, oact);
   }
   signal_lock();
   sigused = (MASK(sig) & jvmsigs) != 0;
   if (jvm_signal_installed && sigused) {
     /* jvm has installed its signal handler for this signal. */
     /* Save the handler. Don't really install it. */
     if (oact != NULL) {
       *oact = sact[sig];
     }
     if (act != NULL) {
       sact[sig] = *act;
     }
     signal_unlock();
     return 0;
   } else if (jvm_signal_installing) {
     /* jvm is installing its signal handlers. Install the new
      * handlers and save the old ones. */
     res = call_os_sigaction(sig, act, &oldAct);
     sact[sig] = oldAct;
     if (oact != NULL) {
       *oact = oldAct;
     }
     /* Record the signals used by jvm */
     jvmsigs |= MASK(sig);
     signal_unlock();
     return res;
   } else {
     /* jvm has no relation with this signal (yet). Install the
      * the handler. */
     res = call_os_sigaction(sig, act, oact);
     signal_unlock();
     return res;
   }
 }
 /* The three functions for the jvm to call into */
 void JVM_begin_signal_setting() {
   signal_lock();
   jvm_signal_installing = true;
   tid = pthread_self();
   signal_unlock();
 }
 void JVM_end_signal_setting() {
   signal_lock();
   jvm_signal_installed = true;
   jvm_signal_installing = false;
   pthread_cond_broadcast(&cond);
   signal_unlock();
 }
 struct sigaction *JVM_get_signal_action(int sig) {
   /* Does race condition make sense here? */
   if ((MASK(sig) & jvmsigs) != 0) {
     return &sact[sig];
   }
   return NULL;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/os/bsd/vm/jsig.c@79841fc03469 (annotated)

src/os/bsd/vm/jsig.c