[dm-devel] [PATCH 2/2] multipathd, libmultipathd: Make delays independent of clock jumps
Bart Van Assche
bart.vanassche at sandisk.com
Thu Sep 29 21:29:17 UTC 2016
Time synchronization software like ntpd can adjust the clock
forwards and backwards. Avoid that the duration of a delay is
influenced by clock jumps initiated by time synchronization
software.
Signed-off-by: Bart Van Assche <bart.vanassche at sandisk.com>
Cc: Mike Christie <mchristi at redhat.com>
---
libmultipath/Makefile | 2 +-
libmultipath/checkers/rbd.c | 12 +++++-------
libmultipath/checkers/tur.c | 20 +++++++++-----------
libmultipath/time-util.c | 42 ++++++++++++++++++++++++++++++++++++++++++
libmultipath/time-util.h | 13 +++++++++++++
multipathd/cli.c | 6 ++----
multipathd/main.c | 39 +++++++++++++++++++++++----------------
multipathd/uxlsnr.c | 19 +++++++++++--------
8 files changed, 106 insertions(+), 47 deletions(-)
create mode 100644 libmultipath/time-util.c
create mode 100644 libmultipath/time-util.h
diff --git a/libmultipath/Makefile b/libmultipath/Makefile
index 92f130c..495cebe 100644
--- a/libmultipath/Makefile
+++ b/libmultipath/Makefile
@@ -47,7 +47,7 @@ endif
OBJS = memory.o parser.o vector.o devmapper.o callout.o \
hwtable.o blacklist.o util.o dmparser.o config.o \
structs.o discovery.o propsel.o dict.o \
- pgpolicies.o debug.o defaults.o uevent.o \
+ pgpolicies.o debug.o defaults.o uevent.o time-util.o \
switchgroup.o uxsock.o print.o alias.o log_pthread.o \
log.o configure.o structs_vec.o sysfs.o prio.o checkers.o \
lock.o waiter.o file.o wwids.o prioritizers/alua_rtpg.o
diff --git a/libmultipath/checkers/rbd.c b/libmultipath/checkers/rbd.c
index 41259c3..bfec2c9 100644
--- a/libmultipath/checkers/rbd.c
+++ b/libmultipath/checkers/rbd.c
@@ -27,6 +27,7 @@
#include "../libmultipath/debug.h"
#include "../libmultipath/uevent.h"
+#include "../libmultipath/time-util.h"
struct rbd_checker_context;
typedef int (thread_fn)(struct rbd_checker_context *ct, char *msg);
@@ -75,7 +76,7 @@ int libcheck_init(struct checker * c)
return 1;
memset(ct, 0, sizeof(struct rbd_checker_context));
ct->holders = 1;
- pthread_cond_init(&ct->active, NULL);
+ pthread_cond_init_mono(&ct->active);
pthread_mutex_init(&ct->lock, NULL);
pthread_spin_init(&ct->hldr_lock, PTHREAD_PROCESS_PRIVATE);
c->context = ct;
@@ -538,12 +539,9 @@ static void *rbd_thread(void *ctx)
static void rbd_timeout(struct timespec *tsp)
{
- struct timeval now;
-
- gettimeofday(&now, NULL);
- tsp->tv_sec = now.tv_sec;
- tsp->tv_nsec = now.tv_usec * 1000;
- tsp->tv_nsec += 1000000; /* 1 millisecond */
+ clock_gettime(CLOCK_MONOTONIC, tsp);
+ tsp->tv_nsec += 1000 * 1000; /* 1 millisecond */
+ normalize_timespec(tsp);
}
static int rbd_exec_fn(struct checker *c, thread_fn *fn)
diff --git a/libmultipath/checkers/tur.c b/libmultipath/checkers/tur.c
index 94e4190..ac272d4 100644
--- a/libmultipath/checkers/tur.c
+++ b/libmultipath/checkers/tur.c
@@ -20,6 +20,7 @@
#include "../libmultipath/debug.h"
#include "../libmultipath/sg_include.h"
#include "../libmultipath/uevent.h"
+#include "../libmultipath/time-util.h"
#define TUR_CMD_LEN 6
#define HEAVY_CHECK_COUNT 10
@@ -60,7 +61,7 @@ int libcheck_init (struct checker * c)
ct->state = PATH_UNCHECKED;
ct->fd = -1;
ct->holders = 1;
- pthread_cond_init(&ct->active, NULL);
+ pthread_cond_init_mono(&ct->active);
pthread_mutex_init(&ct->lock, NULL);
pthread_spin_init(&ct->hldr_lock, PTHREAD_PROCESS_PRIVATE);
c->context = ct;
@@ -237,29 +238,26 @@ static void *tur_thread(void *ctx)
static void tur_timeout(struct timespec *tsp)
{
- struct timeval now;
-
- gettimeofday(&now, NULL);
- tsp->tv_sec = now.tv_sec;
- tsp->tv_nsec = now.tv_usec * 1000;
- tsp->tv_nsec += 1000000; /* 1 millisecond */
+ clock_gettime(CLOCK_MONOTONIC, tsp);
+ tsp->tv_nsec += 1000 * 1000; /* 1 millisecond */
+ normalize_timespec(tsp);
}
static void tur_set_async_timeout(struct checker *c)
{
struct tur_checker_context *ct = c->context;
- struct timeval now;
+ struct timespec now;
- gettimeofday(&now, NULL);
+ clock_gettime(CLOCK_MONOTONIC, &now);
ct->time = now.tv_sec + c->timeout;
}
static int tur_check_async_timeout(struct checker *c)
{
struct tur_checker_context *ct = c->context;
- struct timeval now;
+ struct timespec now;
- gettimeofday(&now, NULL);
+ clock_gettime(CLOCK_MONOTONIC, &now);
return (now.tv_sec > ct->time);
}
diff --git a/libmultipath/time-util.c b/libmultipath/time-util.c
new file mode 100644
index 0000000..6d79c0e
--- /dev/null
+++ b/libmultipath/time-util.c
@@ -0,0 +1,42 @@
+#include <assert.h>
+#include <pthread.h>
+#include <time.h>
+#include "time-util.h"
+
+/* Initialize @cond as a condition variable that uses the monotonic clock */
+void pthread_cond_init_mono(pthread_cond_t *cond)
+{
+ pthread_condattr_t attr;
+ int res;
+
+ res = pthread_condattr_init(&attr);
+ assert(res == 0);
+ res = pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
+ assert(res == 0);
+ res = pthread_cond_init(cond, &attr);
+ assert(res == 0);
+ res = pthread_condattr_destroy(&attr);
+ assert(res == 0);
+}
+
+/* Ensure that 0 <= ts->tv_nsec && ts->tv_nsec < 1000 * 1000 * 1000. */
+void normalize_timespec(struct timespec *ts)
+{
+ while (ts->tv_nsec < 0) {
+ ts->tv_nsec += 1000UL * 1000 * 1000;
+ ts->tv_sec--;
+ }
+ while (ts->tv_nsec >= 1000UL * 1000 * 1000) {
+ ts->tv_nsec -= 1000UL * 1000 * 1000;
+ ts->tv_sec++;
+ }
+}
+
+/* Compute *res = *a - *b */
+void timespecsub(const struct timespec *a, const struct timespec *b,
+ struct timespec *res)
+{
+ res->tv_sec = a->tv_sec - b->tv_sec;
+ res->tv_nsec = a->tv_nsec - b->tv_nsec;
+ normalize_timespec(res);
+}
diff --git a/libmultipath/time-util.h b/libmultipath/time-util.h
new file mode 100644
index 0000000..b76d2aa
--- /dev/null
+++ b/libmultipath/time-util.h
@@ -0,0 +1,13 @@
+#ifndef _TIME_UTIL_H_
+#define _TIME_UTIL_H_
+
+#include <pthread.h>
+
+struct timespec;
+
+void pthread_cond_init_mono(pthread_cond_t *cond);
+void normalize_timespec(struct timespec *ts);
+void timespecsub(const struct timespec *a, const struct timespec *b,
+ struct timespec *res);
+
+#endif /* _TIME_UTIL_H_ */
diff --git a/multipathd/cli.c b/multipathd/cli.c
index 9a19728..e8a9384 100644
--- a/multipathd/cli.c
+++ b/multipathd/cli.c
@@ -454,7 +454,6 @@ parse_cmd (char * cmd, char ** reply, int * len, void * data, int timeout )
struct handler * h;
vector cmdvec = NULL;
struct timespec tmo;
- struct timeval now;
r = get_cmdvec(cmd, &cmdvec);
@@ -476,9 +475,8 @@ parse_cmd (char * cmd, char ** reply, int * len, void * data, int timeout )
/*
* execute handler
*/
- if (gettimeofday(&now, NULL) == 0) {
- tmo.tv_sec = now.tv_sec + timeout;
- tmo.tv_nsec = now.tv_usec * 1000;
+ if (clock_gettime(CLOCK_MONOTONIC, &tmo) == 0) {
+ tmo.tv_sec += timeout;
} else {
tmo.tv_sec = 0;
}
diff --git a/multipathd/main.c b/multipathd/main.c
index 96ef01f..76c049f 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -25,6 +25,11 @@
#include <time.h>
/*
+ * libmultipath
+ */
+#include "time-util.h"
+
+/*
* libcheckers
*/
#include "checkers.h"
@@ -106,7 +111,7 @@ int ignore_new_devs;
enum daemon_status running_state = DAEMON_INIT;
pid_t daemon_pid;
pthread_mutex_t config_lock = PTHREAD_MUTEX_INITIALIZER;
-pthread_cond_t config_cond = PTHREAD_COND_INITIALIZER;
+pthread_cond_t config_cond;
/*
* global copy of vecs for use in sig handlers
@@ -193,7 +198,7 @@ int set_config_state(enum daemon_status state)
if (running_state != DAEMON_IDLE) {
struct timespec ts;
- clock_gettime(CLOCK_REALTIME, &ts);
+ clock_gettime(CLOCK_MONOTONIC, &ts);
ts.tv_sec += 1;
rc = pthread_cond_timedwait(&config_cond,
&config_lock, &ts);
@@ -1744,7 +1749,7 @@ checkerloop (void *ap)
int count = 0;
unsigned int i;
struct itimerval timer_tick_it;
- struct timeval last_time;
+ struct timespec last_time;
struct config *conf;
pthread_cleanup_push(rcu_unregister, NULL);
@@ -1763,24 +1768,23 @@ checkerloop (void *ap)
}
/* Tweak start time for initial path check */
- if (gettimeofday(&last_time, NULL) != 0)
+ if (clock_gettime(CLOCK_MONOTONIC, &last_time) != 0)
last_time.tv_sec = 0;
else
last_time.tv_sec -= 1;
while (1) {
- struct timeval diff_time, start_time, end_time;
+ struct timespec diff_time, start_time, end_time;
int num_paths = 0, ticks = 0, signo, strict_timing, rc = 0;
sigset_t mask;
- if (gettimeofday(&start_time, NULL) != 0)
+ if (clock_gettime(CLOCK_MONOTONIC, &start_time) != 0)
start_time.tv_sec = 0;
if (start_time.tv_sec && last_time.tv_sec) {
- timersub(&start_time, &last_time, &diff_time);
+ timespecsub(&start_time, &last_time, &diff_time);
condlog(4, "tick (%lu.%06lu secs)",
- diff_time.tv_sec, diff_time.tv_usec);
- last_time.tv_sec = start_time.tv_sec;
- last_time.tv_usec = start_time.tv_usec;
+ diff_time.tv_sec, diff_time.tv_nsec / 1000);
+ last_time = start_time;
ticks = diff_time.tv_sec;
} else {
ticks = 1;
@@ -1831,16 +1835,17 @@ checkerloop (void *ap)
lock_cleanup_pop(vecs->lock);
}
- diff_time.tv_usec = 0;
+ diff_time.tv_nsec = 0;
if (start_time.tv_sec &&
- gettimeofday(&end_time, NULL) == 0) {
- timersub(&end_time, &start_time, &diff_time);
+ clock_gettime(CLOCK_MONOTONIC, &end_time) == 0) {
+ timespecsub(&end_time, &start_time, &diff_time);
if (num_paths) {
unsigned int max_checkint;
condlog(3, "checked %d path%s in %lu.%06lu secs",
num_paths, num_paths > 1 ? "s" : "",
- diff_time.tv_sec, diff_time.tv_usec);
+ diff_time.tv_sec,
+ diff_time.tv_nsec / 1000);
conf = get_multipath_config();
max_checkint = conf->max_checkint;
put_multipath_config(conf);
@@ -1861,10 +1866,10 @@ checkerloop (void *ap)
else {
timer_tick_it.it_interval.tv_sec = 0;
timer_tick_it.it_interval.tv_usec = 0;
- if (diff_time.tv_usec) {
+ if (diff_time.tv_nsec) {
timer_tick_it.it_value.tv_sec = 0;
timer_tick_it.it_value.tv_usec =
- (unsigned long)1000000 - diff_time.tv_usec;
+ 1000ULL * 1000 * 1000 - diff_time.tv_nsec;
} else {
timer_tick_it.it_value.tv_sec = 1;
timer_tick_it.it_value.tv_usec = 0;
@@ -2523,6 +2528,8 @@ main (int argc, char *argv[])
strerror(errno));
umask(umask(077) | 022);
+ pthread_cond_init_mono(&config_cond);
+
udev = udev_new();
while ((arg = getopt(argc, argv, ":dsv:k::Bn")) != EOF ) {
diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c
index 7a9faf3..daaaa99 100644
--- a/multipathd/uxlsnr.c
+++ b/multipathd/uxlsnr.c
@@ -32,6 +32,7 @@
#include "defaults.h"
#include "config.h"
#include "mpath_cmd.h"
+#include "time-util.h"
#include "main.h"
#include "cli.h"
@@ -99,21 +100,22 @@ void free_polls (void)
FREE(polls);
}
-void check_timeout(struct timeval start_time, char *inbuf,
+void check_timeout(struct timespec start_time, char *inbuf,
unsigned int timeout)
{
- struct timeval diff_time, end_time;
+ struct timespec diff_time, end_time;
- if (start_time.tv_sec && gettimeofday(&end_time, NULL) == 0) {
- timersub(&end_time, &start_time, &diff_time);
+ if (start_time.tv_sec &&
+ clock_gettime(CLOCK_MONOTONIC, &end_time) == 0) {
unsigned long msecs;
+ timespecsub(&end_time, &start_time, &diff_time);
msecs = diff_time.tv_sec * 1000 +
- diff_time.tv_usec / 1000;
+ diff_time.tv_nsec / (1000 * 1000);
if (msecs > timeout)
condlog(2, "cli cmd '%s' timeout reached "
"after %lu.%06lu secs", inbuf,
- diff_time.tv_sec, diff_time.tv_usec);
+ diff_time.tv_sec, diff_time.tv_nsec / 1000);
}
}
@@ -220,7 +222,7 @@ void * uxsock_listen(uxsock_trigger_fn uxsock_trigger, void * trigger_data)
/* see if a client wants to speak to us */
for (i = 1; i < num_clients + 1; i++) {
if (polls[i].revents & POLLIN) {
- struct timeval start_time;
+ struct timespec start_time;
c = NULL;
pthread_mutex_lock(&client_lock);
@@ -236,7 +238,8 @@ void * uxsock_listen(uxsock_trigger_fn uxsock_trigger, void * trigger_data)
i, polls[i].fd);
continue;
}
- if (gettimeofday(&start_time, NULL) != 0)
+ if (clock_gettime(CLOCK_MONOTONIC, &start_time)
+ != 0)
start_time.tv_sec = 0;
if (recv_packet(c->fd, &inbuf,
uxsock_timeout) != 0) {
--
2.10.0
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