On mer., 2013-05-08 at 13:36 -0500, Benjamin Marzinski wrote:
> This patch changes how multipath's signal handlers work. Instead of
> having sighup and sigusr1 acquire locks and call functions directly,
> they now both simply set atomic variables. These two signals are
> blocked in child(), and all other threads inherit this sigmask. The
> only place in all the multipath code that doesn't block these signals
> is now the ppoll() call by the uxlsnr thread. When it is interrupted
> by a signal, the uxlsnr thread does the actual processing work.
>
> Instead of sigend using mutex locks and condition variables to tell
> the child() function to exit, it now uses a signal_handler safe
> semaphore that child() waits on and exit_daemon() increments.
>
> This patch also switches all the sigprocmask() calls to
> pthread_sigmask()
>
Applied.
Thanks,
Christophe Varoqui
www.opensvc.com
> Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
> ---
> libmultipath/file.c | 4 +--
> libmultipath/lock.c | 9 -----
> libmultipath/lock.h | 1 -
> libmultipath/log_pthread.c | 22 ------------
> libmultipath/waiter.c | 2 --
> multipathd/cli_handlers.c | 4 +--
> multipathd/main.c | 90 +++++++++++++++++++++-------------------------
> multipathd/main.h | 3 +-
> multipathd/uxlsnr.c | 21 +++++++----
> multipathd/uxlsnr.h | 3 ++
> 10 files changed, 65 insertions(+), 94 deletions(-)
>
> diff --git a/libmultipath/file.c b/libmultipath/file.c
> index 5ee46dc..74cde64 100644
> --- a/libmultipath/file.c
> +++ b/libmultipath/file.c
> @@ -98,7 +98,7 @@ lock_file(int fd, char *file_name)
> sigaddset(&set, SIGALRM);
>
> sigaction(SIGALRM, &act, &oldact);
> - sigprocmask(SIG_UNBLOCK, &set, &oldset);
> + pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
>
> alarm(FILE_TIMEOUT);
> err = fcntl(fd, F_SETLKW, &lock);
> @@ -112,7 +112,7 @@ lock_file(int fd, char *file_name)
> condlog(0, "%s is locked. Giving up.", file_name);
> }
>
> - sigprocmask(SIG_SETMASK, &oldset, NULL);
> + pthread_sigmask(SIG_SETMASK, &oldset, NULL);
> sigaction(SIGALRM, &oldact, NULL);
> return err;
> }
> diff --git a/libmultipath/lock.c b/libmultipath/lock.c
> index 4439a51..6ce9a74 100644
> --- a/libmultipath/lock.c
> +++ b/libmultipath/lock.c
> @@ -1,16 +1,7 @@
> #include <pthread.h>
> -#include <signal.h>
> #include "lock.h"
> #include <stdio.h>
>
> -void block_signal (int signum, sigset_t *old)
> -{
> - sigset_t set;
> - sigemptyset(&set);
> - sigaddset(&set, signum);
> - pthread_sigmask(SIG_BLOCK, &set, old);
> -}
> -
> void cleanup_lock (void * data)
> {
> unlock ((*(struct mutex_lock *)data));
> diff --git a/libmultipath/lock.h b/libmultipath/lock.h
> index 6897a74..04ef78d 100644
> --- a/libmultipath/lock.h
> +++ b/libmultipath/lock.h
> @@ -29,6 +29,5 @@ struct mutex_lock {
> #endif
>
> void cleanup_lock (void * data);
> -void block_signal(int signum, sigset_t *old);
>
> #endif /* _LOCK_H */
> diff --git a/libmultipath/log_pthread.c b/libmultipath/log_pthread.c
> index b8f9119..47d75a1 100644
> --- a/libmultipath/log_pthread.c
> +++ b/libmultipath/log_pthread.c
> @@ -22,26 +22,13 @@ pthread_cond_t logev_cond;
>
> int logq_running;
>
> -static void
> -sigusr1 (int sig)
> -{
> - pthread_mutex_lock(&logq_lock);
> - log_reset("multipathd");
> - pthread_mutex_unlock(&logq_lock);
> -}
> -
> void log_safe (int prio, const char * fmt, va_list ap)
> {
> - sigset_t old;
> -
> if (log_thr == (pthread_t)0) {
> syslog(prio, fmt, ap);
> return;
> }
>
> - block_signal(SIGUSR1, &old);
> - block_signal(SIGHUP, NULL);
> -
> pthread_mutex_lock(&logq_lock);
> log_enqueue(prio, fmt, ap);
> pthread_mutex_unlock(&logq_lock);
> @@ -49,8 +36,6 @@ void log_safe (int prio, const char * fmt, va_list ap)
> pthread_mutex_lock(&logev_lock);
> pthread_cond_signal(&logev_cond);
> pthread_mutex_unlock(&logev_lock);
> -
> - pthread_sigmask(SIG_SETMASK, &old, NULL);
> }
>
> void log_thread_flush (void)
> @@ -81,15 +66,8 @@ static void flush_logqueue (void)
>
> static void * log_thread (void * et)
> {
> - struct sigaction sig;
> int running;
>
> - sig.sa_handler = sigusr1;
> - sigemptyset(&sig.sa_mask);
> - sig.sa_flags = 0;
> - if (sigaction(SIGUSR1, &sig, NULL) < 0)
> - logdbg(stderr, "Cannot set signal handler");
> -
> pthread_mutex_lock(&logev_lock);
> logq_running = 1;
> pthread_mutex_unlock(&logev_lock);
> diff --git a/libmultipath/waiter.c b/libmultipath/waiter.c
> index da71543..5094290 100644
> --- a/libmultipath/waiter.c
> +++ b/libmultipath/waiter.c
> @@ -157,8 +157,6 @@ void *waitevent (void *et)
> waiter = (struct event_thread *)et;
> pthread_cleanup_push(free_waiter, et);
>
> - block_signal(SIGUSR1, NULL);
> - block_signal(SIGHUP, NULL);
> while (1) {
> r = waiteventloop(waiter);
>
> diff --git a/multipathd/cli_handlers.c b/multipathd/cli_handlers.c
> index ac648ad..7b1cb62 100644
> --- a/multipathd/cli_handlers.c
> +++ b/multipathd/cli_handlers.c
> @@ -939,8 +939,8 @@ int
> cli_shutdown (void * v, char ** reply, int * len, void * data)
> {
> condlog(3, "shutdown (operator)");
> -
> - return exit_daemon(0);
> + exit_daemon();
> + return 0;
> }
>
> int
> diff --git a/multipathd/main.c b/multipathd/main.c
> index eb4bc8a..0fa1b17 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -17,6 +17,7 @@
> #include <limits.h>
> #include <linux/oom.h>
> #include <libudev.h>
> +#include <semaphore.h>
> #include <mpath_persist.h>
>
> /*
> @@ -51,6 +52,7 @@
> #include <prio.h>
> #include <pgpolicies.h>
> #include <uevent.h>
> +#include <log.h>
>
> #include "main.h"
> #include "pidfile.h"
> @@ -81,13 +83,11 @@ struct mpath_event_param
>
> unsigned int mpath_mx_alloc_len;
>
> -pthread_cond_t exit_cond = PTHREAD_COND_INITIALIZER;
> -pthread_mutex_t exit_mutex = PTHREAD_MUTEX_INITIALIZER;
> -
> int logsink;
> enum daemon_status running_state;
> pid_t daemon_pid;
>
> +static sem_t exit_sem;
> /*
> * global copy of vecs for use in sig handlers
> */
> @@ -833,9 +833,6 @@ out:
> static void *
> ueventloop (void * ap)
> {
> - block_signal(SIGUSR1, NULL);
> - block_signal(SIGHUP, NULL);
> -
> if (uevent_listen())
> condlog(0, "error starting uevent listener");
>
> @@ -845,9 +842,6 @@ ueventloop (void * ap)
> static void *
> uevqloop (void * ap)
> {
> - block_signal(SIGUSR1, NULL);
> - block_signal(SIGHUP, NULL);
> -
> if (uevent_dispatch(&uev_trigger, ap))
> condlog(0, "error starting uevent dispatcher");
>
> @@ -856,9 +850,6 @@ uevqloop (void * ap)
> static void *
> uxlsnrloop (void * ap)
> {
> - block_signal(SIGUSR1, NULL);
> - block_signal(SIGHUP, NULL);
> -
> if (cli_init())
> return NULL;
>
> @@ -908,18 +899,10 @@ uxlsnrloop (void * ap)
> return NULL;
> }
>
> -int
> -exit_daemon (int status)
> +void
> +exit_daemon (void)
> {
> - if (status != 0)
> - fprintf(stderr, "bad exit status. see daemon.log\n");
> -
> - if (running_state != DAEMON_SHUTDOWN) {
> - pthread_mutex_lock(&exit_mutex);
> - pthread_cond_signal(&exit_cond);
> - pthread_mutex_unlock(&exit_mutex);
> - }
> - return status;
> + sem_post(&exit_sem);
> }
>
> const char *
> @@ -1282,7 +1265,6 @@ checkerloop (void *ap)
> struct path *pp;
> int count = 0;
> unsigned int i;
> - sigset_t old;
>
> mlockall(MCL_CURRENT | MCL_FUTURE);
> vecs = (struct vectors *)ap;
> @@ -1296,7 +1278,6 @@ checkerloop (void *ap)
> }
>
> while (1) {
> - block_signal(SIGHUP, &old);
> pthread_cleanup_push(cleanup_lock, &vecs->lock);
> lock(vecs->lock);
> pthread_testcancel();
> @@ -1320,7 +1301,6 @@ checkerloop (void *ap)
> }
>
> lock_cleanup_pop(vecs->lock);
> - pthread_sigmask(SIG_SETMASK, &old, NULL);
> sleep(1);
> }
> return NULL;
> @@ -1480,36 +1460,56 @@ signal_set(int signo, void (*func) (int))
> return (osig.sa_handler);
> }
>
> +void
> +handle_signals(void)
> +{
> + if (reconfig_sig && running_state == DAEMON_RUNNING) {
> + condlog(2, "reconfigure (signal)");
> + pthread_cleanup_push(cleanup_lock,
> + &gvecs->lock);
> + lock(gvecs->lock);
> + pthread_testcancel();
> + reconfigure(gvecs);
> + lock_cleanup_pop(gvecs->lock);
> + }
> + if (log_reset_sig) {
> + condlog(2, "reset log (signal)");
> + pthread_mutex_lock(&logq_lock);
> + log_reset("multipathd");
> + pthread_mutex_unlock(&logq_lock);
> + }
> + reconfig_sig = 0;
> + log_reset_sig = 0;
> +}
> +
> static void
> sighup (int sig)
> {
> - condlog(2, "reconfigure (SIGHUP)");
> -
> - if (running_state != DAEMON_RUNNING)
> - return;
> -
> - reconfigure(gvecs);
> -
> -#ifdef _DEBUG_
> - dbg_free_final(NULL);
> -#endif
> + reconfig_sig = 1;
> }
>
> static void
> sigend (int sig)
> {
> - exit_daemon(0);
> + exit_daemon();
> }
>
> static void
> sigusr1 (int sig)
> {
> - condlog(3, "SIGUSR1 received");
> + log_reset_sig = 1;
> }
>
> static void
> signal_init(void)
> {
> + sigset_t set;
> +
> + sigemptyset(&set);
> + sigaddset(&set, SIGHUP);
> + sigaddset(&set, SIGUSR1);
> + pthread_sigmask(SIG_BLOCK, &set, NULL);
> +
> signal_set(SIGHUP, sighup);
> signal_set(SIGUSR1, sigusr1);
> signal_set(SIGINT, sigend);
> @@ -1582,10 +1582,11 @@ child (void * param)
> struct vectors * vecs;
> struct multipath * mpp;
> int i;
> - sigset_t set;
> int rc, pid_rc;
>
> mlockall(MCL_CURRENT | MCL_FUTURE);
> + sem_init(&exit_sem, 0, 0);
> + signal_init();
>
> setup_thread_attr(&misc_attr, 64 * 1024, 1);
> setup_thread_attr(&waiter_attr, 32 * 1024, 1);
> @@ -1645,7 +1646,6 @@ child (void * param)
> if (!vecs)
> exit(1);
>
> - signal_init();
> setscheduler();
> set_oom_adj();
>
> @@ -1688,25 +1688,17 @@ child (void * param)
> }
> pthread_attr_destroy(&misc_attr);
>
> - pthread_mutex_lock(&exit_mutex);
> /* Startup complete, create logfile */
> pid_rc = pidfile_create(DEFAULT_PIDFILE, daemon_pid);
> /* Ignore errors, we can live without */
>
> running_state = DAEMON_RUNNING;
> - pthread_cond_wait(&exit_cond, &exit_mutex);
> - /* Need to block these to avoid deadlocking */
> - sigemptyset(&set);
> - sigaddset(&set, SIGTERM);
> - sigaddset(&set, SIGINT);
> - pthread_sigmask(SIG_BLOCK, &set, NULL);
>
> /*
> * exit path
> */
> + while(sem_wait(&exit_sem) != 0); /* Do nothing */
> running_state = DAEMON_SHUTDOWN;
> - pthread_sigmask(SIG_UNBLOCK, &set, NULL);
> - block_signal(SIGHUP, NULL);
> lock(vecs->lock);
> if (conf->queue_without_daemon == QUE_NO_DAEMON_OFF)
> vector_foreach_slot(vecs->mpvec, mpp, i)
> diff --git a/multipathd/main.h b/multipathd/main.h
> index 242f5e1..10378ef 100644
> --- a/multipathd/main.h
> +++ b/multipathd/main.h
> @@ -16,7 +16,7 @@ struct prin_resp;
>
> extern pid_t daemon_pid;
>
> -int exit_daemon(int);
> +void exit_daemon(void);
> const char * daemon_status(void);
> int reconfigure (struct vectors *);
> int ev_add_path (struct path *, struct vectors *);
> @@ -35,5 +35,6 @@ int mpath_pr_event_handle(struct path *pp);
> void * mpath_pr_event_handler_fn (void * );
> int update_map_pr(struct multipath *mpp);
> void * mpath_pr_event_handler_fn (void * pathp );
> +void handle_signals(void);
>
> #endif /* MAIN_H */
> diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c
> index 71fc3b4..c0ddd8d 100644
> --- a/multipathd/uxlsnr.c
> +++ b/multipathd/uxlsnr.c
> @@ -8,6 +8,7 @@
> /*
> * A simple domain socket listener
> */
> +#define _GNU_SOURCE
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
> @@ -19,20 +20,21 @@
> #include <sys/socket.h>
> #include <sys/un.h>
> #include <sys/poll.h>
> -
> +#include <signal.h>
> #include <checkers.h>
> -
> #include <memory.h>
> #include <debug.h>
> #include <vector.h>
> #include <structs.h>
> +#include <structs_vec.h>
> #include <uxsock.h>
> #include <defaults.h>
>
> +#include "main.h"
> #include "cli.h"
> #include "uxlsnr.h"
>
> -#define SLEEP_TIME 5000
> +struct timespec sleep_time = {5, 0};
>
> struct client {
> int fd;
> @@ -42,6 +44,8 @@ struct client {
> static struct client *clients;
> static unsigned num_clients;
> struct pollfd *polls;
> +volatile sig_atomic_t reconfig_sig = 0;
> +volatile sig_atomic_t log_reset_sig = 0;
>
> /*
> * handle a new client joining
> @@ -104,6 +108,7 @@ void * uxsock_listen(int (*uxsock_trigger)(char *, char **, int *, void *),
> int rlen;
> char *inbuf;
> char *reply;
> + sigset_t mask;
>
> ux_sock = ux_socket_listen(DEFAULT_SOCKET);
>
> @@ -115,7 +120,9 @@ void * uxsock_listen(int (*uxsock_trigger)(char *, char **, int *, void *),
> pthread_cleanup_push(uxsock_cleanup, NULL);
>
> polls = (struct pollfd *)MALLOC(0);
> -
> + pthread_sigmask(SIG_SETMASK, NULL, &mask);
> + sigdelset(&mask, SIGHUP);
> + sigdelset(&mask, SIGUSR1);
> while (1) {
> struct client *c;
> int i, poll_count;
> @@ -132,11 +139,13 @@ void * uxsock_listen(int (*uxsock_trigger)(char *, char **, int *, void *),
> }
>
> /* most of our life is spent in this call */
> - poll_count = poll(polls, i, SLEEP_TIME);
> + poll_count = ppoll(polls, i, &sleep_time, &mask);
>
> if (poll_count == -1) {
> - if (errno == EINTR)
> + if (errno == EINTR) {
> + handle_signals();
> continue;
> + }
>
> /* something went badly wrong! */
> condlog(0, "poll");
> diff --git a/multipathd/uxlsnr.h b/multipathd/uxlsnr.h
> index c646d5d..8b5a525 100644
> --- a/multipathd/uxlsnr.h
> +++ b/multipathd/uxlsnr.h
> @@ -4,5 +4,8 @@
> void * uxsock_listen(int (*uxsock_trigger)
> (char *, char **, int *, void *),
> void * trigger_data);
> +
> +extern volatile sig_atomic_t reconfig_sig;
> +extern volatile sig_atomic_t log_reset_sig;
> #endif
>
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