X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Ffatal-signal.c;h=b4c5ee6acac26f6565cfaca322e9f1edd090f036;hb=d017eeb9f9ebcb46c24a67fd301b3e36cd26a04e;hp=f6f913ebc0b1d2aa19923240344f40c88df37384;hpb=a0bc29a541fc7dc6e20137d5558e2094d614e6ab;p=sliver-openvswitch.git diff --git a/lib/fatal-signal.c b/lib/fatal-signal.c index f6f913ebc..b4c5ee6ac 100644 --- a/lib/fatal-signal.c +++ b/lib/fatal-signal.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009, 2010 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 @@ -24,20 +23,26 @@ #include #include #include +#include "ovs-thread.h" #include "poll-loop.h" #include "shash.h" +#include "sset.h" +#include "signals.h" #include "socket-util.h" #include "util.h" - -#define THIS_MODULE VLM_fatal_signal #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); @@ -52,11 +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; @@ -64,39 +74,33 @@ fatal_signal_init(void) if (!inited) { size_t i; + assert_single_threaded(); inited = true; - if (pipe(signal_fds)) { - ovs_fatal(errno, "could not create pipe"); - } - set_nonblocking(signal_fds[0]); - set_nonblocking(signal_fds[1]); + ovs_mutex_init(&mutex, PTHREAD_MUTEX_RECURSIVE); + 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); - if (sigaction(sig_nr, NULL, &old_sa)) { - ovs_fatal(errno, "sigaction"); - } + xsigaction(sig_nr, NULL, &old_sa); if (old_sa.sa_handler == SIG_DFL && signal(sig_nr, fatal_signal_handler) == SIG_ERR) { - ovs_fatal(errno, "signal"); + 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 @@ -110,12 +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'. @@ -134,21 +140,41 @@ fatal_signal_handler(int sig_nr) stored_sig_nr = sig_nr; } +/* Check whether a fatal signal has occurred and, if so, call the fatal signal + * hooks and exit. + * + * This function is called automatically by poll_block(), but specialized + * programs that may not always call poll_block() on a regular basis should + * also call it periodically. (Therefore, any function with "block" in its + * name should call fatal_signal_run() each time it is called, either directly + * or through poll_block(), because such functions can only used by specialized + * programs that can afford to block outside their main loop around + * poll_block().) + */ 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(); } } @@ -183,8 +209,8 @@ call_hooks(int sig_nr) } } -/* Files to delete on exit. (The 'data' member of each node is unused.) */ -static struct shash files = SHASH_INITIALIZER(&files); +/* Files to delete on exit. */ +static struct sset files = SSET_INITIALIZER(&files); /* Has a hook function been registered with fatal_signal_add_hook() (and not * cleared by fatal_signal_fork())? */ @@ -199,14 +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); } - if (!shash_find(&files, file)) { - shash_add(&files, file, NULL); - } + sset_add(&files, file); + ovs_mutex_unlock(&mutex); } /* Unregisters 'file' from being unlinked when the program terminates via @@ -214,12 +242,11 @@ fatal_signal_add_file_to_unlink(const char *file) void fatal_signal_remove_file_to_unlink(const char *file) { - struct shash_node *node; + fatal_signal_init(); - node = shash_find(&files, file); - if (node) { - shash_delete(&files, node); - } + 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'. @@ -227,36 +254,44 @@ 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; } static void unlink_files(void *aux OVS_UNUSED) { - do_unlink_files(); + do_unlink_files(); } static void cancel_files(void *aux OVS_UNUSED) { - shash_clear(&files); + sset_clear(&files); added_hook = false; } static void do_unlink_files(void) { - struct shash_node *node; + const char *file; - SHASH_FOR_EACH (node, &files) { - unlink(node->name); + SSET_FOR_EACH (file, &files) { + unlink(file); } } @@ -273,6 +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) {