X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Ffatal-signal.c;h=1770457f3dee50f64d4ca1e1174fc5afd6782c08;hb=f80022d9df98d29ee41176a4bc6cb91025da84b8;hp=64b045d37d992ac7657193819161b77a023b9f58;hpb=d8b30702057c18dac2f35fd766ef5d2a12786eae;p=sliver-openvswitch.git diff --git a/lib/fatal-signal.c b/lib/fatal-signal.c index 64b045d37..1770457f3 100644 --- a/lib/fatal-signal.c +++ b/lib/fatal-signal.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009 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 @@ -26,12 +25,20 @@ #include #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 }; @@ -40,7 +47,8 @@ static sigset_t fatal_signal_set; /* Hooks to call upon catching a signal */ struct hook { - void (*func)(void *aux); + void (*hook_cb)(void *aux); + void (*cancel_cb)(void *aux); void *aux; bool run_at_exit; }; @@ -51,9 +59,6 @@ static size_t n_hooks; static int signal_fds[2]; static volatile sig_atomic_t stored_sig_nr = SIG_ATOMIC_MAX; -/* Disabled by fatal_signal_fork()? */ -static bool disabled; - static void fatal_signal_init(void); static void atexit_handler(void); static void call_hooks(int sig_nr); @@ -68,11 +73,7 @@ fatal_signal_init(void) inited = true; - if (pipe(signal_fds)) { - ovs_fatal(errno, "could not create pipe"); - } - set_nonblocking(signal_fds[0]); - set_nonblocking(signal_fds[1]); + xpipe_nonblocking(signal_fds); sigemptyset(&fatal_signal_set); for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) { @@ -80,31 +81,39 @@ fatal_signal_init(void) 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' to be called when a process termination signal is raised. - * If 'run_at_exit' is true, 'hook' is also called during normal process - * termination, e.g. when exit() is called or when main() returns. +/* 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. * - * The hook is not called immediately from the signal handler but rather the + * '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. */ + * on signal handler functions. + * + * 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 + * the child terminates, not when the parent does. When fatal_signal_fork() is + * called, it calls the 'cancel_cb' function if it is nonnull, passing 'aux', + * to notify that the hook has been canceled. This allows the hook to free + * memory, etc. */ void -fatal_signal_add_hook(void (*func)(void *aux), void *aux, bool run_at_exit) +fatal_signal_add_hook(void (*hook_cb)(void *aux), void (*cancel_cb)(void *aux), + void *aux, bool run_at_exit) { fatal_signal_init(); - assert(n_hooks < MAX_HOOKS); - hooks[n_hooks].func = func; + + 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++; @@ -126,12 +135,30 @@ 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 = stored_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]; + + 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 @@ -144,15 +171,14 @@ fatal_signal_run(void) void fatal_signal_wait(void) { + fatal_signal_init(); poll_fd_wait(signal_fds[0], POLLIN); } static void atexit_handler(void) { - if (!disabled) { - call_hooks(0); - } + call_hooks(0); } static void @@ -167,15 +193,21 @@ call_hooks(int sig_nr) for (i = 0; i < n_hooks; i++) { struct hook *h = &hooks[i]; if (sig_nr || h->run_at_exit) { - h->func(h->aux); + h->hook_cb(h->aux); } } } } -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())? */ +static bool added_hook; static void unlink_files(void *aux); +static void cancel_files(void *aux); static void do_unlink_files(void); /* Registers 'file' to be unlinked when the program terminates via exit() or a @@ -183,15 +215,12 @@ static void do_unlink_files(void); void fatal_signal_add_file_to_unlink(const char *file) { - static bool added_hook = false; if (!added_hook) { added_hook = true; - fatal_signal_add_hook(unlink_files, NULL, 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); } /* Unregisters 'file' from being unlinked when the program terminates via @@ -199,12 +228,7 @@ fatal_signal_add_file_to_unlink(const char *file) void fatal_signal_remove_file_to_unlink(const char *file) { - struct shash_node *node; - - node = shash_find(&files, file); - if (node) { - shash_delete(&files, node); - } + sset_find_and_delete(&files, file); } /* Like fatal_signal_remove_file_to_unlink(), but also unlinks 'file'. @@ -214,7 +238,7 @@ fatal_signal_unlink_file_now(const char *file) { int 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); @@ -223,38 +247,48 @@ fatal_signal_unlink_file_now(const char *file) } static void -unlink_files(void *aux UNUSED) +unlink_files(void *aux OVS_UNUSED) { - do_unlink_files(); + do_unlink_files(); +} + +static void +cancel_files(void *aux OVS_UNUSED) +{ + 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); } } -/* Disables the fatal signal hook mechanism. Following a fork, one of the - * resulting processes can call this function to allow it to terminate without - * triggering fatal signal processing or removing files. Fatal signal - * processing is still enabled in the other process. */ +/* Clears all of the fatal signal hooks without executing them. If any of the + * hooks passed a 'cancel_cb' function to fatal_signal_add_hook(), then those + * functions will be called, allowing them to free resources, etc. + * + * Following a fork, one of the resulting processes can call this function to + * allow it to terminate without calling the hooks registered before calling + * this function. New hooks registered after calling this function will take + * effect normally. */ void fatal_signal_fork(void) { size_t i; - disabled = true; - - for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) { - int sig_nr = fatal_signals[i]; - if (signal(sig_nr, SIG_DFL) == SIG_IGN) { - signal(sig_nr, SIG_IGN); + for (i = 0; i < n_hooks; i++) { + struct hook *h = &hooks[i]; + if (h->cancel_cb) { + h->cancel_cb(h->aux); } } + n_hooks = 0; /* Raise any signals that we have already received with the default * handler. */