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Subject: Re: [PATCH linux-5.2.y-rt only] hrtimer: correct the logic for grab
 expiry lock
To:     Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
        linux-kernel@vger.kernel.org
Cc:     bigeasy@linutronix.de, tglx@linutronix.de, rostedt@goodmis.org,
        linux-rt-users@vger.kernel.org
References: <20200812105053.602-1-zhantao.tang@windriver.com>
 <86790e56-9cec-5cea-8387-f7010b88708b@prevas.dk>
From:   Zhantao Tang <zhantao.tang@windriver.com>
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在 2020/8/12 下午7:45, Rasmus Villemoes 写道:
> On 12/08/2020 12.50, zhantao.tang@windriver.com wrote:
>> From: Zhantao Tang <zhantao.tang@windriver.com>
>>
>> In commit: 47b6de0b7f22 ("hrtimer: Add a missing bracket and hide `migration_base' on !SMP")
>> a inline function is_migration_base() is introduced. But
>> the logic of the hrtimer_grab_expiry_lock was changed.
>>
>> This patch is to correct it.
>>
> Yup, same patch sent back in April, which also had a fixes tag for 5.2.
>
> https://lore.kernel.org/lkml/20200428144026.5882-1-rasmus.villemoes@prevas.dk/
>
> It got picked up for 4.19-rt, dunno why it wasn't for 5.2-rt.

Yes， currently 5.2 rt kernel not fix the issue.

And I checked the 4.19 rt kernel, but  did not find the implementation 
of hrtimer_grab_expiry_lock().

It used hrtimer_wait_for_timer() and the logic is OK.


Thanks,

Zhantao

>
> Rasmus