(#1899402) detect initial timer state from serialized data #165
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… is changed There is difference between time set by the user and real elapsed time because of accuracy feature. If you change the system date(or time) between these times, the timer drops. You can easily reproduce it with the following command. ----------------------------------------------------------- $ systemd-run --on-active=3s ls; sleep 3; date -s "`date`" ----------------------------------------------------------- In the following command, the problem is rarely reproduced. But it exists. --------------------------------------------------------------------------------------------- $ systemd-run --on-active=3s --timer-property=AccuracySec=1us ls ; sleep 1; date -s "`date`" --------------------------------------------------------------------------------------------- Note : Global AccuracySec value. ---------------------------------------------------------------------- $ cat /etc/systemd/system.conf DefaultTimerAccuracySec=1min ---------------------------------------------------------------------- (cherry picked from commit fee04d7) Related: #1899402
We keep a mark whether a single-shot timer was triggered in the caller's
variable initial. When such a timer elapses while we are
serializing/deserializing the inner state, we consider the timer
incorrectly as elapsed and don't trigger it later.
This patch exploits last_trigger timestamp that we already serialize,
hence we can eliminate the argument initial completely.
A reproducer for OnBootSec= timers:
cat >repro.c <<EOD
/*
* Compile: gcc repro.c -o repro
* Run: ./repro
*/
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
int main(int argc, char *argv[]) {
char command[1024];
int pause;
struct timespec now;
while (1) {
usleep(rand() % 200000); // prevent periodic repeats
clock_gettime(CLOCK_MONOTONIC, &now);
printf("%i\n", now.tv_sec);
system("rm -f $PWD/mark");
snprintf(command, 1024, "systemd-run --user --on-boot=%i --timer-property=AccuracySec=100ms "
"touch $PWD/mark", now.tv_sec + 1);
system(command);
system("systemctl --user list-timers");
pause = (1000000000 - now.tv_nsec)/1000 - 70000; // fiddle to hit the middle of reloading
usleep(pause > 0 ? pause : 0);
system("systemctl --user daemon-reload");
sync();
sleep(2);
if (open("./mark", 0) < 0)
if (errno == ENOENT) {
printf("mark file does not exist\n");
break;
}
}
return 0;
}
EOD
(cherry picked from commit aa1f95d)
Resolves: #1899402
systemd-rhel-bot
changed the title
msekletar
approved these changes
Jun 16, 2021
systemd-rhel-bot
removed
pr/needs-review
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