Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Arnd Bergmann <arnd@kernel.org>,
        OPENSOURCE Lukas Hannen 
        <lukas.hannen@opensource.tttech-industrial.com>
Cc:     "EMC: linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "# 3.4.x" <stable@vger.kernel.org>
Subject: Re: [PATCH 5.14 298/334] time: Handle negative seconds correctly in
 timespec64_to_ns()
In-Reply-To: <CAK8P3a0Cnr7LjWmXqSbhnc_jyjseCCztxLv8+v5ojhLXJ+_MyQ@mail.gmail.com>
References: <20210913131113.390368911@linuxfoundation.org>
 <20210913131123.500712780@linuxfoundation.org>
 <CAK8P3a0z5jE=Z3Ps5bFTCFT7CHZR1JQ8VhdntDJAfsUxSPCcEw@mail.gmail.com>
 <AM0PR01MB5410E0963A0AF9A525509DB2EEDC9@AM0PR01MB5410.eurprd01.prod.exchangelabs.com>
 <CAK8P3a0Cnr7LjWmXqSbhnc_jyjseCCztxLv8+v5ojhLXJ+_MyQ@mail.gmail.com>
Date:   Fri, 17 Sep 2021 00:38:41 +0200
Message-ID: <871r5o9mdq.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Thu, Sep 16 2021 at 22:57, Arnd Bergmann wrote:
> On Thu, Sep 16, 2021 at 6:50 PM OPENSOURCE Lukas Hannen
> <lukas.hannen@opensource.tttech-industrial.com> wrote:
> I did stumble over one small detail:
>
>         if (ts->tv_sec <= KTIME_SEC_MIN)
>                 return KTIME_MIN;
>
> I think this is not entirely correct for the case of tv_sec==KTIME_SEC_MIN
> with a nonzero tv_nsec, as we now round down to the full second. Not sure
> if that's worth changing, as we also round up for any value between
> KTIME_SEC_MAX*NSEC_PER_SEC and KTIME_MAX, or between
> KTIME_MIN and KTIME_SEC_MIN*NSEC_PER_SEC.
> In practice I guess we care very little about the last nanosecond in the corner
> cases.

It's completely irrelevant whether the result is off by one second
related to the 292 years limit.

Thanks,

        tglx