From 24c242ec7abb3d21fa0b1da6bb251521dc1717b5 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Mon, 25 Jan 2021 15:30:39 +0100 Subject: ntp: Use freezable workqueue for RTC synchronization The bug fixed by commit e3fab2f3de081e98 ("ntp: Fix RTC synchronization on 32-bit platforms") revealed an underlying issue: RTC synchronization may happen anytime, even while the system is partially suspended. On systems where the RTC is connected to an I2C bus, the I2C bus controller may already or still be suspended, triggering a WARNING during suspend or resume from s2ram: WARNING: CPU: 0 PID: 124 at drivers/i2c/i2c-core.h:54 __i2c_transfer+0x634/0x680 i2c i2c-6: Transfer while suspended [...] Workqueue: events_power_efficient sync_hw_clock [...] (__i2c_transfer) (i2c_transfer) (regmap_i2c_read) ... (da9063_rtc_set_time) (rtc_set_time) (sync_hw_clock) (process_one_work) Fix this race condition by using the freezable instead of the normal power-efficient workqueue. Signed-off-by: Geert Uytterhoeven Signed-off-by: Thomas Gleixner Acked-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/20210125143039.1051912-1-geert+renesas@glider.be --- kernel/time/ntp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 87389b9e21ab..5247afd7f345 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -502,7 +502,7 @@ static struct hrtimer sync_hrtimer; static enum hrtimer_restart sync_timer_callback(struct hrtimer *timer) { - queue_work(system_power_efficient_wq, &sync_work); + queue_work(system_freezable_power_efficient_wq, &sync_work); return HRTIMER_NORESTART; } @@ -668,7 +668,7 @@ void ntp_notify_cmos_timer(void) * just a pointless work scheduled. */ if (ntp_synced() && !hrtimer_is_queued(&sync_hrtimer)) - queue_work(system_power_efficient_wq, &sync_work); + queue_work(system_freezable_power_efficient_wq, &sync_work); } static void __init ntp_init_cmos_sync(void) -- cgit