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SubjectRe: [PATCH] net: apm: xgene: force XGene enet driver to re-balance IRQ usage
Date


On 09/17/2018 09:35 PM, David Miller wrote:
> From: Al Stone <ahs3@redhat.com>
> Date: Mon, 17 Sep 2018 17:35:33 -0600
>
>> @@ -866,8 +866,11 @@ static int xgene_enet_napi(struct napi_struct *napi, const int budget)
>> processed = xgene_enet_process_ring(ring, budget);
>>
>> if (processed != budget) {
>> + struct irq_desc *desc = irq_to_desc(ring->irq);
>> +
>> napi_complete_done(napi, processed);

The problem could be that the driver isn't checking the
napi_complete_done() return code. It was changed to return a bool and
the check should be more like:

if ((processed != budget) && napi_complete_done(napi, processed)) {

If it returns false, then the driver will get called for polling again
after having issued enable_irq() and it well then issue the enable_irq()
a second (or more) time without having the matching diable_irq().

Thanks,
Tom

>> - enable_irq(ring->irq);
>> + if (desc && desc->depth > 0)
>> + enable_irq(ring->irq);
>
> I really can't accept a patch that grovels into IRQ layer internals
> to work around a driver's IRQ enable/disable usage problem.
>
> Sorry.
>
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