X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Ffatal-signal.c;h=e980f4be96b41f38b54e306f8f4a379f74078ffb;hb=015ac88281952a1b43ad46e9e6300db1c6e3647b;hp=c7e87dbe9fbca7bfb976f0bc921620efcaf508c5;hpb=279c9e030818e039bb1c26be76e2cc1e8f6b13a6;p=sliver-openvswitch.git diff --git a/lib/fatal-signal.c b/lib/fatal-signal.c index c7e87dbe9..e980f4be9 100644 --- a/lib/fatal-signal.c +++ b/lib/fatal-signal.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks. + * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -15,7 +15,6 @@ */ #include #include "fatal-signal.h" -#include #include #include #include @@ -24,6 +23,7 @@ #include #include #include +#include "ovs-thread.h" #include "poll-loop.h" #include "shash.h" #include "sset.h" @@ -32,14 +32,17 @@ #include "util.h" #include "vlog.h" +#include "type-props.h" + +#ifndef SIG_ATOMIC_MAX +#define SIG_ATOMIC_MAX TYPE_MAXIMUM(sig_atomic_t) +#endif + VLOG_DEFINE_THIS_MODULE(fatal_signal); /* Signals to catch. */ static const int fatal_signals[] = { SIGTERM, SIGINT, SIGHUP, SIGALRM }; -/* Signals to catch as a sigset_t. */ -static sigset_t fatal_signal_set; - /* Hooks to call upon catching a signal */ struct hook { void (*hook_cb)(void *aux); @@ -54,11 +57,16 @@ static size_t n_hooks; static int signal_fds[2]; static volatile sig_atomic_t stored_sig_nr = SIG_ATOMIC_MAX; -static void fatal_signal_init(void); +static struct ovs_mutex mutex; + static void atexit_handler(void); static void call_hooks(int sig_nr); -static void +/* Initializes the fatal signal handling module. Calling this function is + * optional, because calling any other function in the module will also + * initialize it. However, in a multithreaded program, the module must be + * initialized while the process is still single-threaded. */ +void fatal_signal_init(void) { static bool inited = false; @@ -66,35 +74,33 @@ fatal_signal_init(void) if (!inited) { size_t i; + assert_single_threaded(); inited = true; - xpipe(signal_fds); - set_nonblocking(signal_fds[0]); - set_nonblocking(signal_fds[1]); + ovs_mutex_init_recursive(&mutex); + xpipe_nonblocking(signal_fds); - sigemptyset(&fatal_signal_set); for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) { int sig_nr = fatal_signals[i]; struct sigaction old_sa; - sigaddset(&fatal_signal_set, sig_nr); xsigaction(sig_nr, NULL, &old_sa); if (old_sa.sa_handler == SIG_DFL && signal(sig_nr, fatal_signal_handler) == SIG_ERR) { - VLOG_FATAL("signal failed (%s)", strerror(errno)); + VLOG_FATAL("signal failed (%s)", ovs_strerror(errno)); } } atexit(atexit_handler); } } -/* Registers 'hook_cb' to be called when a process termination signal is - * raised. If 'run_at_exit' is true, 'hook_cb' is also called during normal - * process termination, e.g. when exit() is called or when main() returns. +/* Registers 'hook_cb' to be called from inside poll_block() following a fatal + * signal. 'hook_cb' does not need to be async-signal-safe. In a + * multithreaded program 'hook_cb' might be called from any thread, with + * threads other than the one running 'hook_cb' in unknown states. * - * 'hook_cb' is not called immediately from the signal handler but rather the - * next time the poll loop iterates, so it is freed from the usual restrictions - * on signal handler functions. + * If 'run_at_exit' is true, 'hook_cb' is also called during normal process + * termination, e.g. when exit() is called or when main() returns. * * If the current process forks, fatal_signal_fork() may be called to clear the * parent process's fatal signal hooks, so that 'hook_cb' is only called when @@ -108,12 +114,14 @@ fatal_signal_add_hook(void (*hook_cb)(void *aux), void (*cancel_cb)(void *aux), { fatal_signal_init(); - assert(n_hooks < MAX_HOOKS); + ovs_mutex_lock(&mutex); + ovs_assert(n_hooks < MAX_HOOKS); hooks[n_hooks].hook_cb = hook_cb; hooks[n_hooks].cancel_cb = cancel_cb; hooks[n_hooks].aux = aux; hooks[n_hooks].run_at_exit = run_at_exit; n_hooks++; + ovs_mutex_unlock(&mutex); } /* Handles fatal signal number 'sig_nr'. @@ -146,18 +154,27 @@ fatal_signal_handler(int sig_nr) void fatal_signal_run(void) { - int sig_nr; + sig_atomic_t sig_nr; fatal_signal_init(); sig_nr = stored_sig_nr; if (sig_nr != SIG_ATOMIC_MAX) { + char namebuf[SIGNAL_NAME_BUFSIZE]; + + ovs_mutex_lock(&mutex); + + VLOG_WARN("terminating with signal %d (%s)", + (int)sig_nr, signal_name(sig_nr, namebuf, sizeof namebuf)); call_hooks(sig_nr); /* Re-raise the signal with the default handling so that the program * termination status reflects that we were killed by this signal */ signal(sig_nr, SIG_DFL); raise(sig_nr); + + ovs_mutex_unlock(&mutex); + NOT_REACHED(); } } @@ -208,12 +225,16 @@ static void do_unlink_files(void); void fatal_signal_add_file_to_unlink(const char *file) { + fatal_signal_init(); + + ovs_mutex_lock(&mutex); if (!added_hook) { added_hook = true; fatal_signal_add_hook(unlink_files, cancel_files, NULL, true); } sset_add(&files, file); + ovs_mutex_unlock(&mutex); } /* Unregisters 'file' from being unlinked when the program terminates via @@ -221,7 +242,11 @@ fatal_signal_add_file_to_unlink(const char *file) void fatal_signal_remove_file_to_unlink(const char *file) { + fatal_signal_init(); + + ovs_mutex_lock(&mutex); sset_find_and_delete(&files, file); + ovs_mutex_unlock(&mutex); } /* Like fatal_signal_remove_file_to_unlink(), but also unlinks 'file'. @@ -229,13 +254,21 @@ fatal_signal_remove_file_to_unlink(const char *file) int fatal_signal_unlink_file_now(const char *file) { - int error = unlink(file) ? errno : 0; + int error; + + fatal_signal_init(); + + ovs_mutex_lock(&mutex); + + error = unlink(file) ? errno : 0; if (error) { - VLOG_WARN("could not unlink \"%s\" (%s)", file, strerror(error)); + VLOG_WARN("could not unlink \"%s\" (%s)", file, ovs_strerror(error)); } fatal_signal_remove_file_to_unlink(file); + ovs_mutex_unlock(&mutex); + return error; } @@ -275,6 +308,8 @@ fatal_signal_fork(void) { size_t i; + assert_single_threaded(); + for (i = 0; i < n_hooks; i++) { struct hook *h = &hooks[i]; if (h->cancel_cb) {