@@ -786,8 +786,9 @@ static long hardpps_update_freq(struct pps_normtime freq_norm)
time_status |= STA_PPSERROR;
pps_errcnt++;
pps_dec_freq_interval();
- pr_err("hardpps: PPSERROR: interval too long - %ld s\n",
- freq_norm.sec);
+ printk_deferred(KERN_ERR
+ "hardpps: PPSERROR: interval too long - %ld s\n",
+ freq_norm.sec);
return 0;
}
@@ -800,7 +801,8 @@ static long hardpps_update_freq(struct pps_normtime freq_norm)
delta = shift_right(ftemp - pps_freq, NTP_SCALE_SHIFT);
pps_freq = ftemp;
if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) {
- pr_warning("hardpps: PPSWANDER: change=%ld\n", delta);
+ printk_deferred(KERN_WARNING
+ "hardpps: PPSWANDER: change=%ld\n", delta);
time_status |= STA_PPSWANDER;
pps_stbcnt++;
pps_dec_freq_interval();
@@ -844,8 +846,9 @@ static void hardpps_update_phase(long error)
* the time offset is updated.
*/
if (jitter > (pps_jitter << PPS_POPCORN)) {
- pr_warning("hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
- jitter, (pps_jitter << PPS_POPCORN));
+ printk_deferred(KERN_WARNING
+ "hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
+ jitter, (pps_jitter << PPS_POPCORN));
time_status |= STA_PPSJITTER;
pps_jitcnt++;
} else if (time_status & STA_PPSTIME) {
@@ -902,7 +905,7 @@ void __hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
time_status |= STA_PPSJITTER;
/* restart the frequency calibration interval */
pps_fbase = *raw_ts;
- pr_err("hardpps: PPSJITTER: bad pulse\n");
+ printk_deferred(KERN_ERR "hardpps: PPSJITTER: bad pulse\n");
return;
}
@@ -852,8 +852,9 @@ static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
struct timespec *delta)
{
if (!timespec_valid_strict(delta)) {
- printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
- "sleep delta value!\n");
+ printk_deferred(KERN_WARNING
+ "__timekeeping_inject_sleeptime: Invalid "
+ "sleep delta value!\n");
return;
}
tk_xtime_add(tk, delta);
@@ -1157,7 +1158,7 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
if (unlikely(tk->clock->maxadj &&
(tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) {
- printk_once(KERN_WARNING
+ printk_once_deferred(KERN_WARNING
"Adjusting %s more than 11%% (%ld vs %ld)\n",
tk->clock->name, (long)tk->mult + adj,
(long)tk->clock->mult + tk->clock->maxadj);
Jiri Bohac pointed out that there are rare but potential deadlock possibilities when calling printk while holding the timekeeping seqlock. This is due to printk() triggering console sem wakeup, which can cause scheduling code to trigger hrtimers which may try to read the time. Specifically, as Jiri pointed out, that path is: printk vprintk_emit console_unlock up(&console_sem) __up wake_up_process try_to_wake_up ttwu_do_activate ttwu_activate activate_task enqueue_task enqueue_task_fair hrtick_update hrtick_start_fair hrtick_start_fair get_time ktime_get --> endless loop on read_seqcount_retry(&timekeeper_seq, ...) This patch tries to avoid this issue by using printk_deferred (previously named printk_sched) which should defer printing via a irq_work_queue. Cc: Jan Kara <jack@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jiri Bohac <jbohac@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Steven Rostedt <rostedt@goodmis.org> Reported-by: Jiri Bohac <jbohac@suse.cz> Signed-off-by: John Stultz <john.stultz@linaro.org> --- kernel/time/ntp.c | 15 +++++++++------ kernel/time/timekeeping.c | 7 ++++--- 2 files changed, 13 insertions(+), 9 deletions(-)