linux-kernel - Re: [PATCH v3] ipc: Update semtimedop() to use hrtimer

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Message-ID: <5FEE7AB6-7560-4998-A7A3-B60A4B32E1DE@oracle.com>
Date:   Thu, 28 Apr 2022 22:23:40 +0000
From:   Prakash Sangappa <prakash.sangappa@...cle.com>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     Davidlohr Bueso <dave@...olabs.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "manfred@...orfullife.com" <manfred@...orfullife.com>
Subject: Re: [PATCH v3] ipc: Update semtimedop() to use hrtimer



> On Apr 28, 2022, at 3:02 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> 
> On Thu, Apr 28 2022 at 13:50, Davidlohr Bueso wrote:
>> On Thu, 28 Apr 2022, Prakash Sangappa wrote:
>>> -		if (timeout)
>>> -			jiffies_left = schedule_timeout(jiffies_left);
>>> -		else
>>> -			schedule();
>>> +		timed_out = !schedule_hrtimeout_range(exp,
>>> +				current->timer_slack_ns, HRTIMER_MODE_ABS);
>> 
>> I'm wondering if the slack parameter instead of passing the timer_slack_ns
>> value immediately, we should do a rt_task() check and pass zero if so.
> 
> We should have a wrapper function which takes care of that instead of
> having checks all over the place.

Ok  it can be an inline function in sched.h which returns appropriate 
slack time. Use that in  futex_wait() and sigtimedwait() also in addition to 
semtimedop() & mqueue codepath?

Should that be a separate patch?

Thanks,
-Prakash

> 
> Thanks,
> 
>        tglx