Use sigtimedwait(2) for signals handling in primary process.
This fixes various races and eliminates use of pthread* API in signal handler. Pointed out by: kib With help from: jilles MFC after: 2 weeks Obtained from: Wheel Systems Sp. z o.o. http://www.wheelsystems.com
This commit is contained in:
Pawel Jakub Dawidek
parent
ff6bb1f8b3
commit
6d0c801ea9
@ -46,6 +46,7 @@ __FBSDID("$FreeBSD$");
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#include <fcntl.h>
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#include <libgeom.h>
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#include <pthread.h>
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#include <signal.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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@ -132,8 +133,6 @@ static pthread_cond_t sync_cond;
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* The lock below allows to synchornize access to remote connections.
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*/
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static pthread_rwlock_t *hio_remote_lock;
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static pthread_mutex_t hio_guard_lock;
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static pthread_cond_t hio_guard_cond;
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/*
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* Lock to synchronize metadata updates. Also synchronize access to
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@ -152,13 +151,9 @@ static pthread_mutex_t metadata_lock;
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*/
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#define HAST_NCOMPONENTS 2
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/*
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* Number of seconds to sleep between keepalive packets.
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* Number of seconds to sleep between reconnect retries or keepalive packets.
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*/
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#define KEEPALIVE_SLEEP 10
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/*
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* Number of seconds to sleep between reconnect retries.
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*/
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#define RECONNECT_SLEEP 5
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#define RETRY_SLEEP 10
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#define ISCONNECTED(res, no) \
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((res)->hr_remotein != NULL && (res)->hr_remoteout != NULL)
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@ -230,7 +225,11 @@ static void *ggate_send_thread(void *arg);
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static void *sync_thread(void *arg);
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static void *guard_thread(void *arg);
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static void sighandler(int sig);
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static void
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dummy_sighandler(int sig __unused)
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{
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/* Nothing to do. */
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}
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static void
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cleanup(struct hast_resource *res)
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@ -319,6 +318,7 @@ init_environment(struct hast_resource *res __unused)
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{
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struct hio *hio;
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unsigned int ii, ncomps;
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sigset_t mask;
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/*
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* In the future it might be per-resource value.
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@ -389,8 +389,6 @@ init_environment(struct hast_resource *res __unused)
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TAILQ_INIT(&hio_done_list);
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mtx_init(&hio_done_list_lock);
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cv_init(&hio_done_list_cond);
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mtx_init(&hio_guard_lock);
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cv_init(&hio_guard_cond);
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mtx_init(&metadata_lock);
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/*
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@ -431,10 +429,10 @@ init_environment(struct hast_resource *res __unused)
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/*
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* Turn on signals handling.
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*/
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signal(SIGINT, sighandler);
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signal(SIGTERM, sighandler);
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signal(SIGHUP, sighandler);
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signal(SIGCHLD, sighandler);
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/* Because SIGCHLD is ignored by default, setup dummy handler for it. */
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PJDLOG_VERIFY(signal(SIGCHLD, dummy_sighandler) != SIG_ERR);
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PJDLOG_VERIFY(sigfillset(&mask) == 0);
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PJDLOG_VERIFY(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
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}
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static void
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@ -893,16 +891,6 @@ remote_close(struct hast_resource *res, int ncomp)
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* Stop synchronization if in-progress.
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*/
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sync_stop();
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/*
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* Wake up guard thread (if we are not called from within guard thread),
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* so it can immediately start reconnect.
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*/
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if (!mtx_owned(&hio_guard_lock)) {
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mtx_lock(&hio_guard_lock);
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cv_signal(&hio_guard_cond);
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mtx_unlock(&hio_guard_lock);
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}
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}
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/*
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@ -1733,35 +1721,6 @@ sync_thread(void *arg __unused)
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return (NULL);
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}
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static void
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sighandler(int sig)
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{
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bool unlock;
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switch (sig) {
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case SIGINT:
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case SIGTERM:
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sigexit_received = true;
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break;
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case SIGHUP:
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sighup_received = true;
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break;
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case SIGCHLD:
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sigchld_received = true;
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break;
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default:
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assert(!"invalid condition");
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}
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/*
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* Racy, but if we cannot obtain hio_guard_lock here, we don't
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* want to risk deadlock.
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*/
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unlock = mtx_trylock(&hio_guard_lock);
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cv_signal(&hio_guard_cond);
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if (unlock)
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mtx_unlock(&hio_guard_lock);
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}
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static void
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config_reload(void)
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{
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@ -1973,48 +1932,48 @@ guard_thread(void *arg)
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{
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struct hast_resource *res = arg;
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unsigned int ii, ncomps;
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struct timespec timeout;
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time_t lastcheck, now;
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int timeout;
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sigset_t mask;
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int signo;
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ncomps = HAST_NCOMPONENTS;
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lastcheck = time(NULL);
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PJDLOG_VERIFY(sigemptyset(&mask) == 0);
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PJDLOG_VERIFY(sigaddset(&mask, SIGHUP) == 0);
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PJDLOG_VERIFY(sigaddset(&mask, SIGINT) == 0);
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PJDLOG_VERIFY(sigaddset(&mask, SIGTERM) == 0);
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PJDLOG_VERIFY(sigaddset(&mask, SIGCHLD) == 0);
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timeout.tv_nsec = 0;
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signo = -1;
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for (;;) {
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if (sigexit_received) {
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switch (signo) {
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case SIGHUP:
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config_reload();
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break;
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case SIGINT:
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case SIGTERM:
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sigexit_received = true;
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primary_exitx(EX_OK,
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"Termination signal received, exiting.");
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break;
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default:
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break;
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}
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if (sighup_received) {
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sighup_received = false;
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config_reload();
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}
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hook_check(sigchld_received);
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if (sigchld_received)
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sigchld_received = false;
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hook_check(signo == SIGCHLD);
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pjdlog_debug(2, "remote_guard: Checking connections.");
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mtx_lock(&hio_guard_lock);
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timeout = KEEPALIVE_SLEEP;
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for (ii = 0; ii < ncomps; ii++) {
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if (!ISCONNECTED(res, ii)) {
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timeout = RECONNECT_SLEEP;
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break;
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}
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}
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now = time(NULL);
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if (lastcheck + timeout <= now) {
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timeout = KEEPALIVE_SLEEP;
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for (ii = 0; ii < ncomps; ii++) {
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if (lastcheck + RETRY_SLEEP <= now) {
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for (ii = 0; ii < ncomps; ii++)
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guard_one(res, ii);
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if (!ISCONNECTED(res, ii))
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timeout = RECONNECT_SLEEP;
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}
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lastcheck = now;
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}
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/* Sleep only if a signal wasn't delivered in the meantime. */
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if (!sigexit_received && !sighup_received && !sigchld_received)
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cv_timedwait(&hio_guard_cond, &hio_guard_lock, timeout);
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mtx_unlock(&hio_guard_lock);
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timeout.tv_sec = RETRY_SLEEP;
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signo = sigtimedwait(&mask, NULL, &timeout);
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}
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/* NOTREACHED */
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return (NULL);
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