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

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Date:   Thu, 19 Nov 2020 22:03:49 +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 19:56, John Garry wrote:
>>>>    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.
>> 
>
> Just mentioning a couple of things here, which could be a clue to what 
> is going on:
> - the device is behind mbigen secondary irq controller
> - the flow in the LLDD is to allocate all 128 interrupts during probe, 
> but we only register handlers for a subset with device managed API

Right, but if the driver is removed then the interrupts should be
deallocated, right?

Thanks,

        tglx