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2024-11-28ntp: Remove invalid cast in time offset mathMarcelo Dalmas
Due to an unsigned cast, adjtimex() returns the wrong offest when using ADJ_MICRO and the offset is negative. In this case a small negative offset returns approximately 4.29 seconds (~ 2^32/1000 milliseconds) due to the unsigned cast of the negative offset. This cast was added when the kernel internal struct timex was changed to use type long long for the time offset value to address the problem of a 64bit/32bit division on 32bit systems. The correct cast would have been (s32), which is correct as time_offset can only be in the range of [INT_MIN..INT_MAX] because the shift constant used for calculating it is 32. But that's non-obvious. Remove the cast and use div_s64() to cure the issue. [ tglx: Fix white space damage, use div_s64() and amend the change log ] Fixes: ead25417f82e ("timex: use __kernel_timex internally") Signed-off-by: Marcelo Dalmas <marcelo.dalmas@ge.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/SJ0P101MB03687BF7D5A10FD3C49C51E5F42E2@SJ0P101MB0368.NAMP101.PROD.OUTLOOK.COM
2024-10-02ntp: Move pps monitors into ntp_dataThomas Gleixner
Finalize the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-21-2d52f4e13476@linutronix.de
2024-10-02ntp: Move pps_freq/stabil into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-20-2d52f4e13476@linutronix.de
2024-10-02ntp: Move pps_shift/intcnt into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-19-2d52f4e13476@linutronix.de
2024-10-02ntp: Move pps_fbase into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-18-2d52f4e13476@linutronix.de
2024-10-02ntp: Move pps_jitter into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-17-2d52f4e13476@linutronix.de
2024-10-02ntp: Move pps_ft into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-16-2d52f4e13476@linutronix.de
2024-10-02ntp: Move pps_valid into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-15-2d52f4e13476@linutronix.de
2024-10-02ntp: Move ntp_next_leap_sec into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-14-2d52f4e13476@linutronix.de
2024-10-02ntp: Move time_adj/ntp_tick_adj into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-13-2d52f4e13476@linutronix.de
2024-10-02ntp: Move time_freq/reftime into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-12-2d52f4e13476@linutronix.de
2024-10-02ntp: Move time_max/esterror into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-11-2d52f4e13476@linutronix.de
2024-10-02ntp: Move time_offset/constant into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-10-2d52f4e13476@linutronix.de
2024-10-02ntp: Move tick_stat* into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-9-2d52f4e13476@linutronix.de
2024-10-02ntp: Move tick_length* into ntp_dataThomas Gleixner
Continue the conversion from static variables to struct based data. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-8-2d52f4e13476@linutronix.de
2024-10-02ntp: Introduce struct ntp_dataThomas Gleixner
All NTP data is held in static variables. That prevents the NTP code from being reuasble for non-system time timekeepers, e.g. per PTP clock timekeeping. Introduce struct ntp_data and move tick_usec into it for a start. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-7-2d52f4e13476@linutronix.de
2024-10-02ntp: Read reference time only onceThomas Gleixner
The reference time is required twice in ntp_update_offset(). It will not change in the meantime as the calling code holds the timekeeper lock. Read it only once and store it into a local variable. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-6-2d52f4e13476@linutronix.de
2024-10-02ntp: Convert functions with only two states to boolThomas Gleixner
is_error_status() and ntp_synced() return whether a state is set or not. Both functions use unsigned int for it even if it would be a perfect job for a bool. Use bool instead of unsigned int. And while at it, move ntp_synced() function to the place where it is used. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-5-2d52f4e13476@linutronix.de
2024-10-02ntp: Cleanup formatting of codeAnna-Maria Behnsen
Code is partially formatted in a creative way which makes reading harder. Examples are function calls over several lines where the indentation does not start at the same height then the open bracket after the function name. Improve formatting but do not make a functional change. Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-4-2d52f4e13476@linutronix.de
2024-10-02ntp: Clean up commentsThomas Gleixner
Usage of different comment formatting makes fast reading and parsing the code harder. There are several multi-line comments which do not follow the coding style by starting with a line only containing '/*'. There are also comments which do not start with capitals. Clean up all those comments to be consistent and remove comments which document the obvious. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-3-2d52f4e13476@linutronix.de
2024-10-02ntp: Make tick_usec staticThomas Gleixner
There are no users of tick_usec outside of the NTP core code. Therefore make tick_usec static. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-2-2d52f4e13476@linutronix.de
2024-10-02ntp: Remove unused tick_nsecThomas Gleixner
tick_nsec is only updated in the NTP core, but there are no users. Remove it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-1-2d52f4e13476@linutronix.de
2024-09-10ntp: Make sure RTC is synchronized when time goes backwardsBenjamin ROBIN
sync_hw_clock() is normally called every 11 minutes when time is synchronized. This issue is that this periodic timer uses the REALTIME clock, so when time moves backwards (the NTP server jumps into the past), the timer expires late. If the timer expires late, which can be days later, the RTC will no longer be updated, which is an issue if the device is abruptly powered OFF during this period. When the device will restart (when powered ON), it will have the date prior to the ADJ_SETOFFSET call. A normal NTP server should not jump in the past like that, but it is possible... Another way of reproducing this issue is to use phc2sys to synchronize the REALTIME clock with, for example, an IRIG timecode with the source always starting at the same date (not synchronized). Also, if the time jump in the future by less than 11 minutes, the RTC may not be updated immediately (minor issue). Consider the following scenario: - Time is synchronized, and sync_hw_clock() was just called (the timer expires in 11 minutes). - A time jump is realized in the future by a couple of minutes. - The time is synchronized again. - Users may expect that RTC to be updated as soon as possible, and not after 11 minutes (for the same reason, if a power loss occurs in this period). Cancel periodic timer on any time jump (ADJ_SETOFFSET) greater than or equal to 1s. The timer will be relaunched at the end of do_adjtimex() if NTP is still considered synced. Otherwise the timer will be relaunched later when NTP is synced. This way, when the time is synchronized again, the RTC is updated after less than 2 seconds. Signed-off-by: Benjamin ROBIN <dev@benjarobin.fr> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/all/20240908140836.203911-1-dev@benjarobin.fr
2024-08-05ntp: Safeguard against time_constant overflowJustin Stitt
Using syzkaller with the recently reintroduced signed integer overflow sanitizer produces this UBSAN report: UBSAN: signed-integer-overflow in ../kernel/time/ntp.c:738:18 9223372036854775806 + 4 cannot be represented in type 'long' Call Trace: handle_overflow+0x171/0x1b0 __do_adjtimex+0x1236/0x1440 do_adjtimex+0x2be/0x740 The user supplied time_constant value is incremented by four and then clamped to the operating range. Before commit eea83d896e31 ("ntp: NTP4 user space bits update") the user supplied value was sanity checked to be in the operating range. That change removed the sanity check and relied on clamping after incrementing which does not work correctly when the user supplied value is in the overflow zone of the '+ 4' operation. The operation requires CAP_SYS_TIME and the side effect of the overflow is NTP getting out of sync. Similar to the fixups for time_maxerror and time_esterror, clamp the user space supplied value to the operating range. [ tglx: Switch to clamping ] Fixes: eea83d896e31 ("ntp: NTP4 user space bits update") Signed-off-by: Justin Stitt <justinstitt@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20240517-b4-sio-ntp-c-v2-1-f3a80096f36f@google.com Closes: https://github.com/KSPP/linux/issues/352
2024-08-05ntp: Clamp maxerror and esterror to operating rangeJustin Stitt
Using syzkaller alongside the newly reintroduced signed integer overflow sanitizer spits out this report: UBSAN: signed-integer-overflow in ../kernel/time/ntp.c:461:16 9223372036854775807 + 500 cannot be represented in type 'long' Call Trace: handle_overflow+0x171/0x1b0 second_overflow+0x2d6/0x500 accumulate_nsecs_to_secs+0x60/0x160 timekeeping_advance+0x1fe/0x890 update_wall_time+0x10/0x30 time_maxerror is unconditionally incremented and the result is checked against NTP_PHASE_LIMIT, but the increment itself can overflow, resulting in wrap-around to negative space. Before commit eea83d896e31 ("ntp: NTP4 user space bits update") the user supplied value was sanity checked to be in the operating range. That change removed the sanity check and relied on clamping in handle_overflow() which does not work correctly when the user supplied value is in the overflow zone of the '+ 500' operation. The operation requires CAP_SYS_TIME and the side effect of the overflow is NTP getting out of sync. Miroslav confirmed that the input value should be clamped to the operating range and the same applies to time_esterror. The latter is not used by the kernel, but the value still should be in the operating range as it was before the sanity check got removed. Clamp them to the operating range. [ tglx: Changed it to clamping and included time_esterror ] Fixes: eea83d896e31 ("ntp: NTP4 user space bits update") Signed-off-by: Justin Stitt <justinstitt@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Miroslav Lichvar <mlichvar@redhat.com> Link: https://lore.kernel.org/all/20240517-b4-sio-ntp-usec-v2-1-d539180f2b79@google.com Closes: https://github.com/KSPP/linux/issues/354
2021-03-22timekeeping, clocksource: Fix various typos in commentsIngo Molnar
Fix ~56 single-word typos in timekeeping & clocksource code comments. Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Stephen Boyd <sboyd@kernel.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: linux-kernel@vger.kernel.org
2021-02-05ntp: Use freezable workqueue for RTC synchronizationGeert Uytterhoeven
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
2021-01-12ntp: Fix RTC synchronization on 32-bit platformsGeert Uytterhoeven
Due to an integer overflow, RTC synchronization now happens every 2s instead of the intended 11 minutes. Fix this by forcing 64-bit arithmetic for the sync period calculation. Annotate the other place which multiplies seconds for consistency as well. Fixes: c9e6189fb03123a7 ("ntp: Make the RTC synchronization more reliable") Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20210111103956.290378-1-geert+renesas@glider.be
2020-12-11ntp: Consolidate the RTC update implementationThomas Gleixner
The code for the legacy RTC and the RTC class based update are pretty much the same. Consolidate the common parts into one function and just invoke the actual setter functions. For RTC class based devices the update code checks whether the offset is valid for the device, which is usually not the case for the first invocation. If it's not the same it stores the correct offset and lets the caller try again. That's not much different from the previous approach where the first invocation had a pretty low probability to actually hit the allowed window. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220542.355743355@linutronix.de
2020-12-11ntp: Make the RTC sync offset less obscureThomas Gleixner
The current RTC set_offset_nsec value is not really intuitive to understand. tsched twrite(t2.tv_sec - 1) t2 (seconds increment) The offset is calculated from twrite based on the assumption that t2 - twrite == 1s. That means for the MC146818 RTC the offset needs to be negative so that the write happens 500ms before t2. It's easier to understand when the whole calculation is based on t2. That avoids negative offsets and the meaning is obvious: t2 - twrite: The time defined by the chip when seconds increment after the write. twrite - tsched: The time for the transport to the point where the chip is updated. ==> set_offset_nsec = t2 - tsched ttransport = twrite - tsched tRTCinc = t2 - twrite ==> set_offset_nsec = ttransport + tRTCinc tRTCinc is a chip property and can be obtained from the data sheet. ttransport depends on how the RTC is connected. It is close to 0 for directly accessible RTCs. For RTCs behind a slow bus, e.g. i2c, it's the time required to send the update over the bus. This can be estimated or even calibrated, but that's a different problem. Adjust the implementation and update comments accordingly. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220542.263204937@linutronix.de
2020-12-11ntp, rtc: Move rtc_set_ntp_time() to ntp codeThomas Gleixner
rtc_set_ntp_time() is not really RTC functionality as the code is just a user of RTC. Move it into the NTP code which allows further cleanups. Requested-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220542.166871172@linutronix.de
2020-12-11ntp: Make the RTC synchronization more reliableThomas Gleixner
Miroslav reported that the periodic RTC synchronization in the NTP code fails more often than not to hit the specified update window. The reason is that the code uses delayed_work to schedule the update which needs to be in thread context as the underlying RTC might be connected via a slow bus, e.g. I2C. In the update function it verifies whether the current time is correct vs. the requirements of the underlying RTC. But delayed_work is using the timer wheel for scheduling which is inaccurate by design. Depending on the distance to the expiry the wheel gets less granular to allow batching and to avoid the cascading of the original timer wheel. See 500462a9de65 ("timers: Switch to a non-cascading wheel") and the code for further details. The code already deals with this by splitting the 660 seconds period into a long 659 seconds timer and then retrying with a smaller delta. But looking at the actual granularities of the timer wheel (which depend on the HZ configuration) the 659 seconds timer ends up in an outer wheel level and is affected by a worst case granularity of: HZ Granularity 1000 32s 250 16s 100 40s So the initial timer can be already off by max 12.5% which is not a big issue as the period of the sync is defined as ~11 minutes. The fine grained second attempt schedules to the desired update point with a timer expiring less than a second from now. Depending on the actual delta and the HZ setting even the second attempt can end up in outer wheel levels which have a large enough granularity to make the correctness check fail. As this is a fundamental property of the timer wheel there is no way to make this more accurate short of iterating in one jiffies steps towards the update point. Switch it to an hrtimer instead which schedules the actual update work. The hrtimer will expire precisely (max 1 jiffie delay when high resolution timers are not available). The actual scheduling delay of the work is the same as before. The update is triggered from do_adjtimex() which is a bit racy but not much more racy than it was before: if (ntp_synced()) queue_delayed_work(system_power_efficient_wq, &sync_work, 0); which is racy when the work is currently executed and has not managed to reschedule itself. This becomes now: if (ntp_synced() && !hrtimer_is_queued(&sync_hrtimer)) queue_work(system_power_efficient_wq, &sync_work, 0); which is racy when the hrtimer has expired and the work is currently executed and has not yet managed to rearm the hrtimer. Not a big problem as it just schedules work for nothing. The new implementation has a safe guard in place to catch the case where the hrtimer is queued on entry to the work function and avoids an extra update attempt of the RTC that way. Reported-by: Miroslav Lichvar <mlichvar@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Miroslav Lichvar <mlichvar@redhat.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220542.062910520@linutronix.de
2019-11-12ntp/y2038: Remove incorrect time_t truncationArnd Bergmann
A cast to 'time_t' was accidentally left in place during the conversion of __do_adjtimex() to 64-bit timestamps, so the resulting value is incorrectly truncated. Remove the cast so the 64-bit time gets propagated correctly. Fixes: ead25417f82e ("timex: use __kernel_timex internally") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20191108203435.112759-2-arnd@arndb.de
2019-06-22ntp: Limit TAI-UTC offsetMiroslav Lichvar
Don't allow the TAI-UTC offset of the system clock to be set by adjtimex() to a value larger than 100000 seconds. This prevents an overflow in the conversion to int, prevents the CLOCK_TAI clock from getting too far ahead of the CLOCK_REALTIME clock, and it is still large enough to allow leap seconds to be inserted at the maximum rate currently supported by the kernel (once per day) for the next ~270 years, however unlikely it is that someone can survive a catastrophic event which slowed down the rotation of the Earth so much. Reported-by: Weikang shi <swkhack@gmail.com> Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Stephen Boyd <sboyd@kernel.org> Link: https://lkml.kernel.org/r/20190618154713.20929-1-mlichvar@redhat.com
2019-05-16Merge branch 'timers-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull time fixes from Ingo Molnar: "A TIA adjtimex interface extension, and a POSIX compliance ABI fix for timespec64 users" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: ntp: Allow TAI-UTC offset to be set to zero y2038: Make CONFIG_64BIT_TIME unconditional
2019-05-09ntp: Allow TAI-UTC offset to be set to zeroMiroslav Lichvar
The ADJ_TAI adjtimex mode sets the TAI-UTC offset of the system clock. It is typically set by NTP/PTP implementations and it is automatically updated by the kernel on leap seconds. The initial value is zero (which applications may interpret as unknown), but this value cannot be set by adjtimex. This limitation seems to go back to the original "nanokernel" implementation by David Mills. Change the ADJ_TAI check to accept zero as a valid TAI-UTC offset in order to allow setting it back to the initial value. Fixes: 153b5d054ac2 ("ntp: support for TAI") Suggested-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Link: https://lkml.kernel.org/r/20190417084833.7401-1-mlichvar@redhat.com
2019-04-15ntp: Audit NTP parameters adjustmentOndrej Mosnacek
Emit an audit record every time selected NTP parameters are modified from userspace (via adjtimex(2) or clock_adjtime(2)). These parameters may be used to indirectly change system clock, and thus their modifications should be audited. Such events will now generate records of type AUDIT_TIME_ADJNTPVAL containing the following fields: - op -- which value was adjusted: - offset -- corresponding to the time_offset variable - freq -- corresponding to the time_freq variable - status -- corresponding to the time_status variable - adjust -- corresponding to the time_adjust variable - tick -- corresponding to the tick_usec variable - tai -- corresponding to the timekeeping's TAI offset - old -- the old value - new -- the new value Example records: type=TIME_ADJNTPVAL msg=audit(1530616044.507:7): op=status old=64 new=8256 type=TIME_ADJNTPVAL msg=audit(1530616044.511:11): op=freq old=0 new=49180377088000 The records of this type will be associated with the corresponding syscall records. An overview of parameter changes that can be done via do_adjtimex() (based on information from Miroslav Lichvar) and whether they are audited: __timekeeping_set_tai_offset() -- sets the offset from the International Atomic Time (AUDITED) NTP variables: time_offset -- can adjust the clock by up to 0.5 seconds per call and also speed it up or slow down by up to about 0.05% (43 seconds per day) (AUDITED) time_freq -- can speed up or slow down by up to about 0.05% (AUDITED) time_status -- can insert/delete leap seconds and it also enables/ disables synchronization of the hardware real-time clock (AUDITED) time_maxerror, time_esterror -- change error estimates used to inform userspace applications (NOT AUDITED) time_constant -- controls the speed of the clock adjustments that are made when time_offset is set (NOT AUDITED) time_adjust -- can temporarily speed up or slow down the clock by up to 0.05% (AUDITED) tick_usec -- a more extreme version of time_freq; can speed up or slow down the clock by up to 10% (AUDITED) Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Reviewed-by: Richard Guy Briggs <rgb@redhat.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-02-07timex: use __kernel_timex internallyDeepa Dinamani
struct timex is not y2038 safe. Replace all uses of timex with y2038 safe __kernel_timex. Note that struct __kernel_timex is an ABI interface definition. We could define a new structure based on __kernel_timex that is only available internally instead. Right now, there isn't a strong motivation for this as the structure is isolated to a few defined struct timex interfaces and such a structure would be exactly the same as struct timex. The patch was generated by the following coccinelle script: virtual patch @depends on patch forall@ identifier ts; expression e; @@ ( - struct timex ts; + struct __kernel_timex ts; | - struct timex ts = {}; + struct __kernel_timex ts = {}; | - struct timex ts = e; + struct __kernel_timex ts = e; | - struct timex *ts; + struct __kernel_timex *ts; | (memset \| copy_from_user \| copy_to_user \)(..., - sizeof(struct timex)) + sizeof(struct __kernel_timex)) ) @depends on patch forall@ identifier ts; identifier fn; @@ fn(..., - struct timex *ts, + struct __kernel_timex *ts, ...) { ... } @depends on patch forall@ identifier ts; identifier fn; @@ fn(..., - struct timex *ts) { + struct __kernel_timex *ts) { ... } Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Cc: linux-alpha@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2018-12-28Merge tag 'y2038-for-4.21' of ↵Linus Torvalds
ssh://gitolite.kernel.org:/pub/scm/linux/kernel/git/arnd/playground Pull y2038 updates from Arnd Bergmann: "More syscalls and cleanups This concludes the main part of the system call rework for 64-bit time_t, which has spread over most of year 2018, the last six system calls being - ppoll - pselect6 - io_pgetevents - recvmmsg - futex - rt_sigtimedwait As before, nothing changes for 64-bit architectures, while 32-bit architectures gain another entry point that differs only in the layout of the timespec structure. Hopefully in the next release we can wire up all 22 of those system calls on all 32-bit architectures, which gives us a baseline version for glibc to start using them. This does not include the clock_adjtime, getrusage/waitid, and getitimer/setitimer system calls. I still plan to have new versions of those as well, but they are not required for correct operation of the C library since they can be emulated using the old 32-bit time_t based system calls. Aside from the system calls, there are also a few cleanups here, removing old kernel internal interfaces that have become unused after all references got removed. The arch/sh cleanups are part of this, there were posted several times over the past year without a reaction from the maintainers, while the corresponding changes made it into all other architectures" * tag 'y2038-for-4.21' of ssh://gitolite.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: timekeeping: remove obsolete time accessors vfs: replace current_kernel_time64 with ktime equivalent timekeeping: remove timespec_add/timespec_del timekeeping: remove unused {read,update}_persistent_clock sh: remove board_time_init() callback sh: remove unused rtc_sh_get/set_time infrastructure sh: sh03: rtc: push down rtc class ops into driver sh: dreamcast: rtc: push down rtc class ops into driver y2038: signal: Add compat_sys_rt_sigtimedwait_time64 y2038: signal: Add sys_rt_sigtimedwait_time32 y2038: socket: Add compat_sys_recvmmsg_time64 y2038: futex: Add support for __kernel_timespec y2038: futex: Move compat implementation into futex.c io_pgetevents: use __kernel_timespec pselect6: use __kernel_timespec ppoll: use __kernel_timespec signal: Add restore_user_sigmask() signal: Add set_user_sigmask()
2018-12-18timekeeping: remove unused {read,update}_persistent_clockArnd Bergmann
After arch/sh has removed the last reference to these functions, we can remove them completely and just rely on the 64-bit time_t based versions. This cleans up a rather ugly use of __weak functions. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: John Stultz <john.stultz@linaro.org>
2018-12-18ntp: Remove duplicated includeYueHaibing
Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: <john.stultz@linaro.org> Cc: <sboyd@kernel.org> Link: https://lkml.kernel.org/r/20181209062225.4344-1-yuehaibing@huawei.com
2018-07-19timekeeping/ntp: Constify some function argumentsOndrej Mosnacek
Add 'const' to some function arguments and variables to make it easier to read the code. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Stephen Boyd <sboyd@kernel.org> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> [jstultz: Also fixup pre-existing checkpatch warnings for prototype arguments with no variable name] Signed-off-by: John Stultz <john.stultz@linaro.org>
2018-07-19ntp: Use kstrtos64 for s64 variableOndrej Mosnacek
...instead of kstrtol with a dirty cast. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Stephen Boyd <sboyd@kernel.org> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2018-07-19ntp: Remove redundant argumentsOndrej Mosnacek
The 'ts' argument of process_adj_status() and process_adjtimex_modes() is unused and can be safely removed. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Stephen Boyd <sboyd@kernel.org> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2018-06-19timekeeping: Use ktime_get_real_ts64() instead of getnstimeofday64()Arnd Bergmann
The two do the same, this moves all users to the newer name for consistency. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: y2038@lists.linaro.org Cc: Stephen Boyd <sboyd@kernel.org> Cc: Miroslav Lichvar <mlichvar@redhat.com> Link: https://lkml.kernel.org/r/20180618140811.2998503-3-arnd@arndb.de
2018-04-06jiffies: Introduce USER_TICK_USEC and redefine TICK_USECRafael J. Wysocki
Since the subsequent changes will need a TICK_USEC definition analogous to TICK_NSEC, rename the existing TICK_USEC as USER_TICK_USEC, update its users and redefine TICK_USEC accordingly. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
2017-11-13Merge branch 'timers-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer updates from Thomas Gleixner: "Yet another big pile of changes: - More year 2038 work from Arnd slowly reaching the point where we need to think about the syscalls themself. - A new timer function which allows to conditionally (re)arm a timer only when it's either not running or the new expiry time is sooner than the armed expiry time. This allows to use a single timer for multiple timeout requirements w/o caring about the first expiry time at the call site. - A new NMI safe accessor to clock real time for the printk timestamp work. Can be used by tracing, perf as well if required. - A large number of timer setup conversions from Kees which got collected here because either maintainers requested so or they simply got ignored. As Kees pointed out already there are a few trivial merge conflicts and some redundant commits which was unavoidable due to the size of this conversion effort. - Avoid a redundant iteration in the timer wheel softirq processing. - Provide a mechanism to treat RTC implementations depending on their hardware properties, i.e. don't inflict the write at the 0.5 seconds boundary which originates from the PC CMOS RTC to all RTCs. No functional change as drivers need to be updated separately. - The usual small updates to core code clocksource drivers. Nothing really exciting" * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (111 commits) timers: Add a function to start/reduce a timer pstore: Use ktime_get_real_fast_ns() instead of __getnstimeofday() timer: Prepare to change all DEFINE_TIMER() callbacks netfilter: ipvs: Convert timers to use timer_setup() scsi: qla2xxx: Convert timers to use timer_setup() block/aoe: discover_timer: Convert timers to use timer_setup() ide: Convert timers to use timer_setup() drbd: Convert timers to use timer_setup() mailbox: Convert timers to use timer_setup() crypto: Convert timers to use timer_setup() drivers/pcmcia: omap1: Fix error in automated timer conversion ARM: footbridge: Fix typo in timer conversion drivers/sgi-xp: Convert timers to use timer_setup() drivers/pcmcia: Convert timers to use timer_setup() drivers/memstick: Convert timers to use timer_setup() drivers/macintosh: Convert timers to use timer_setup() hwrng/xgene-rng: Convert timers to use timer_setup() auxdisplay: Convert timers to use timer_setup() sparc/led: Convert timers to use timer_setup() mips: ip22/32: Convert timers to use timer_setup() ...
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-30timekeeping: Consolidate timekeeping_inject_offset codeArnd Bergmann
The code to check the adjtimex() or clock_adjtime() arguments is spread out across multiple files for presumably only historic reasons. As a preparatation for a rework to get rid of the use of 'struct timeval' and 'struct timespec' in there, this moves all the portions into kernel/time/timekeeping.c and marks them as 'static'. The warp_clock() function here is not as closely related as the others, but I feel it still makes sense to move it here in order to consolidate all callers of timekeeping_inject_offset(). Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Stephen Boyd <stephen.boyd@linaro.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> [jstultz: Whitespace fixup] Signed-off-by: John Stultz <john.stultz@linaro.org>
2017-10-30rtc: Allow rtc drivers to specify the tv_nsec value for ntpJason Gunthorpe
ntp is currently hardwired to try and call the rtc set when wall clock tv_nsec is 0.5 seconds. This historical behaviour works well with certain PC RTCs, but is not universal to all rtc hardware. Change how this works by introducing the driver specific concept of set_offset_nsec, the delay between current wall clock time and the target time to set (with a 0 tv_nsecs). For x86-style CMOS set_offset_nsec should be -0.5 s which causes the last second to be written 0.5 s after it has started. For compat with the old rtc_set_ntp_time, the value is defaulted to + 0.5 s, which causes the next second to be written 0.5s before it starts, as things were before this patch. Testing shows many non-x86 RTCs would like set_offset_nsec ~= 0, so ultimately each RTC driver should set the set_offset_nsec according to its needs, and non x86 architectures should stop using update_persistent_clock64 in order to access this feature. Future patches will revise the drivers as needed. Since CMOS and RTC now have very different handling they are split into two dedicated code paths, sharing the support code, and ifdefs are replaced with IS_ENABLED. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Stephen Boyd <stephen.boyd@linaro.org> Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> Signed-off-by: John Stultz <john.stultz@linaro.org>