linux-kernel - Re: [Issue] timer callback registered with mod

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Message-ID: <87mto2dvl9.ffs@tglx>
Date:   Fri, 24 Sep 2021 14:08:50 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     maninder1.s@...sung.com, "fweisbec@...il.com" <fweisbec@...il.com>,
        "mingo@...nel.org" <mingo@...nel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Vaneet Narang <v.narang@...sung.com>,
        AMIT SAHRAWAT <a.sahrawat@...sung.com>,
        Chung-Ki Woo <chungki0201.woo@...sung.com>
Subject: Re: [Issue] timer callback registered with mod_timer is getting
 called beforetime

On Fri, Sep 24 2021 at 12:23, Maninder Singh wrote:
?
> As we checekd code if CPU responsible for updating jiffies value(lets
> say CPU0) has interrupts disabled for 60 ms and in mean time other
> CPU(CPU1) registers new timer for (jiffies + x) value. its callback
> will be called before time.

So you run some stuff for 60ms with interrupts disabled and now you are
asking what's wrong?

The answer is simply: Keeping interrupts disabled for 60ms is wrong.

Anything else is just a symptom.

Thanks,

        tglx