From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Martin Wilck Date: Tue, 15 Sep 2020 12:46:36 +0200 Subject: [PATCH] multipathd: generalize and fix wait_for_state_change_if() It's unlikely but not impossible that other threads change the state while we're waiting, and if we grab the lock again, it's still not what we wanted. We need to continue waiting until either the condition is met, or time timeout expired. Moreover, generalize this code so that it can also be used in set_config_state(). Reviewed-by: Benjamin Marzinski Signed-off-by: Benjamin Marzinski --- multipathd/main.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/multipathd/main.c b/multipathd/main.c index d081b3e9..1fb0ee62 100644 --- a/multipathd/main.c +++ b/multipathd/main.c @@ -223,6 +223,23 @@ static void config_cleanup(__attribute__((unused)) void *arg) pthread_mutex_unlock(&config_lock); } +#define __wait_for_state_change(condition, ms) \ + ({ \ + struct timespec tmo; \ + int rc = 0; \ + \ + if (condition) { \ + get_monotonic_time(&tmo); \ + tmo.tv_nsec += (ms) * 1000 * 1000; \ + normalize_timespec(&tmo); \ + do \ + rc = pthread_cond_timedwait( \ + &config_cond, &config_lock, &tmo); \ + while (rc == 0 && (condition)); \ + } \ + rc; \ + }) + /* * If the current status is @oldstate, wait for at most @ms milliseconds * for the state to change, and return the new state, which may still be @@ -232,20 +249,14 @@ enum daemon_status wait_for_state_change_if(enum daemon_status oldstate, unsigned long ms) { enum daemon_status st; - struct timespec tmo; if (oldstate == DAEMON_SHUTDOWN) return DAEMON_SHUTDOWN; pthread_mutex_lock(&config_lock); pthread_cleanup_push(config_cleanup, NULL); + __wait_for_state_change(running_state == oldstate, ms); st = running_state; - if (st == oldstate && clock_gettime(CLOCK_MONOTONIC, &tmo) == 0) { - tmo.tv_nsec += ms * 1000 * 1000; - normalize_timespec(&tmo); - (void)pthread_cond_timedwait(&config_cond, &config_lock, &tmo); - st = running_state; - } pthread_cleanup_pop(1); return st; }