linux-kernel - Re: [PATCH v2 1/3] genirq/affinity: Add irq_update_affinity

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Date:   Thu, 19 Nov 2020 19:09:37 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     John Garry <john.garry@...wei.com>, gregkh@...uxfoundation.org,
        rafael@...nel.org, martin.petersen@...cle.com, jejb@...ux.ibm.com
Cc:     linuxarm@...wei.com, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org, maz@...nel.org
Subject: Re: [PATCH v2 1/3] genirq/affinity: Add irq_update_affinity_desc()

On Thu, Nov 19 2020 at 09:31, John Garry wrote:
>>   1) Interrupt does not exist. Definitely a full fail
>> 
>>   2) Interrupt is already started up. Not a good idea on init() and
>>      a clear fail.
>> 
>>   3) Interrupt has already been switched to managed. Double init is not
>>      really a good sign either.
>
> I just tested that and case 3) would be a problem. I don't see us 
> clearing the managed flag when free'ing the interrupt. So with 
> CONFIG_DEBUG_TEST_DRIVER_REMOVE=y, we attempt this affinity update 
> twice, and error from the irqd_affinity_is_managed() check.

That means the interrupt is not deallocated and reallocated, which does
not make sense to me.

Thanks,

        tglx