https://github.com/torvalds/linux
Revision 24c242ec7abb3d21fa0b1da6bb251521dc1717b5 authored by Geert Uytterhoeven on 25 January 2021, 14:30:39 UTC, committed by Thomas Gleixner on 05 February 2021, 17:03:13 UTC
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 <geert+renesas@glider.be>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20210125143039.1051912-1-geert+renesas@glider.be

1 parent ebb22a0
History
Tip revision: 24c242ec7abb3d21fa0b1da6bb251521dc1717b5 authored by Geert Uytterhoeven on 25 January 2021, 14:30:39 UTC
ntp: Use freezable workqueue for RTC synchronization
Tip revision: 24c242e
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.clang-format -rw-r--r-- 16.3 KB
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