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From: Thomas Gleixner <tglx@linutronix.de>
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To: John Stultz <jstultz@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Stephen Boyd <sboyd@kernel.org>,
 Anna-Maria Behnsen <anna-maria@linutronix.de>, Frederic Weisbecker
 <frederic@kernel.org>, Shuah Khan <shuah@kernel.org>, Miroslav Lichvar
 <mlichvar@redhat.com>, linux-kselftest@vger.kernel.org,
 kernel-team@android.com, Lei Chen <lei.chen@smartx.com>
Subject: Re: [RFC PATCH 1/2] time/timekeeping: Fix possible inconsistencies
 in _COARSE clockids
In-Reply-To: <CANDhNCrxmoK98pmL-ynPVu9tMpyrjMXZ_L7-R0nV2r=YGMg0OA@mail.gmail.com>
References: <CANDhNCoueki=keYNcNr4eXqgLFPh3VupDJC0hFqxm4FNKfGzYg@mail.gmail.com>
 <20250315003800.3054684-1-jstultz@google.com> <877c4q5c9i.ffs@tglx>
 <CANDhNCqzHYJfaap5-TYPmtbaPm6AkS85hKdeSnprhEqMCAYcPw@mail.gmail.com>
 <874izs66el.ffs@tglx>
 <CANDhNCrxmoK98pmL-ynPVu9tMpyrjMXZ_L7-R0nV2r=YGMg0OA@mail.gmail.com>
Date: Fri, 21 Mar 2025 17:17:07 +0100
Message-ID: <877c4i2wak.ffs@tglx>
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On Thu, Mar 20 2025 at 19:01, John Stultz wrote:
> On Sun, Mar 16, 2025 at 9:56=E2=80=AFPM Thomas Gleixner <tglx@linutronix.=
de> wrote:
>> #define TK_CLEAR_NTP            (1 << 0)
>> #define TK_CLOCK_WAS_SET        (1 << 1)
>>
>> So it clears NTP instead. Not really what you want either. :)
>
> Hey Thomas,
>    Sorry for the slow reply here.   So I agree with you that we don't
> want to set clock_set above, that was my mistake. But this last bit I
> don't think is right, as timekeeping advance() just returns a bool
> (return !!clock_set;), which is used to decide to call clock_was_set()
> or not  - not the argument passed to clock_was_set().

timekeeping_advance() also uses the clock_set internally.

      clock_set |=3D ....
      timekeeping_update_from_shadow(..., clock_set);

timekeeping_update_from_shadow() evaluates the TK... bits.

Thanks,

        tglx