From: Denys Vlasenko Date: Mon, 25 Jan 2010 18:30:16 +0000 (+0100) Subject: ntpd: explain why scripts can be run in quick succession X-Git-Tag: 1_16_0~3 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=24928ffd8d6eb7f410ea0a7b4530086cecfeea6e;p=oweals%2Fbusybox.git ntpd: explain why scripts can be run in quick succession Signed-off-by: Denys Vlasenko --- diff --git a/examples/var_service/ntpd/ntp.script b/examples/var_service/ntpd/ntp.script index 90299ae8e..76c34bf74 100755 --- a/examples/var_service/ntpd/ntp.script +++ b/examples/var_service/ntpd/ntp.script @@ -1,10 +1,12 @@ #!/bin/sh -exec 2>/dev/null -echo "`tail -n 99 "$0.log"`" >"$0.log" - -exec >>"$0.log" -exec 2>&1 +# Note that there is no provision to prevent several copies of the script +# to be run in quick succession. In fact, it happens rather often +# if initial syncronization results in a step. +# You will see "step" and then "stratum" script runs, sometimes +# as close as only 0.002 seconds apart. +# +# Script should be ready to deal with this. dt=`date '+%Y-%m-%d %H:%M:%S'` @@ -13,17 +15,23 @@ if test x"$stratum" != x"" \ && test 4 -ge "$stratum" \ && test 128 -le "$poll_interval" \ ; then + echo "`tail -n 199 -- "$0.log" 2>/dev/null`" >"$0.log.$$" echo "$dt: $1"\ "freq_drift_ppm=$freq_drift_ppm"\ "offset=$offset"\ "stratum=$stratum"\ "poll_interval=$poll_interval,"\ - "setting hardware clock" + "setting hardware clock"\ + >>"$0.log.$$" + mv -- "$0.log.$$" "$0.log" exec hwclock --systohc fi +echo "`tail -n 199 -- "$0.log" 2>/dev/null`" >"$0.log.$$" echo "$dt: $1"\ "freq_drift_ppm=$freq_drift_ppm"\ "offset=$offset"\ "stratum=$stratum"\ "poll_interval=$poll_interval"\ + >>"$0.log.$$" +mv -- "$0.log.$$" "$0.log" diff --git a/networking/ntpd.c b/networking/ntpd.c index 95dfdb119..04df3fa7f 100644 --- a/networking/ntpd.c +++ b/networking/ntpd.c @@ -735,6 +735,13 @@ send_query_to_peer(peer_t *p) } +/* Note that there is no provision to prevent several run_scripts + * to be done in quick succession. In fact, it happens rather often + * if initial syncronization results in a step. + * You will see "step" and then "stratum" script runs, sometimes + * as close as only 0.002 seconds apart. + * Script should be ready to deal with this. + */ static void run_script(const char *action, double offset) { char *argv[3]; @@ -1185,8 +1192,8 @@ update_local_clock(peer_t *p) abs_offset = fabs(offset); #if 0 - /* If needed, -S script can detect this by looking at $offset - * env var and kill parent */ + /* If needed, -S script can do it by looking at $offset + * env var and killing parent */ /* If the offset is too large, give up and go home */ if (abs_offset > PANIC_THRESHOLD) { bb_error_msg_and_die("offset %f far too big, exiting", offset); @@ -2007,7 +2014,7 @@ int ntpd_main(int argc UNUSED_PARAM, char **argv) nfds = poll(pfd, i, timeout * 1000); gettime1900d(); /* sets G.cur_time */ if (nfds <= 0) { - if (G.cur_time - G.last_script_run > 11*60) { + if (G.script_name && G.cur_time - G.last_script_run > 11*60) { /* Useful for updating battery-backed RTC and such */ run_script("periodic", G.last_update_offset); gettime1900d(); /* sets G.cur_time */