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

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Date:   Thu, 19 Nov 2020 19:56:28 +0000
From:   John Garry <john.garry@...wei.com>
To:     Thomas Gleixner <tglx@...utronix.de>, <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()

Hi Thomas,

>>>    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

Thanks,
John