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

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Message-ID: <4929e93d-508a-4670-9450-66e4fc85be7e@redhat.com>
Date:   Tue, 18 Sep 2018 17:15:31 -0600
From:   Al Stone <ahs3@...hat.com>
To:     "Lendacky, Thomas" <Thomas.Lendacky@....com>,
        David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "isubramanian@....com" <isubramanian@....com>,
        "kchudgar@....com" <kchudgar@....com>,
        "qnguyen@....com" <qnguyen@....com>
Subject: Re: [PATCH] net: apm: xgene: force XGene enet driver to re-balance
 IRQ usage

On 09/18/2018 05:09 PM, Lendacky, Thomas wrote:
> 
> 
> On 09/17/2018 09:35 PM, David Miller wrote:
>> From: Al Stone <ahs3@...hat.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

Aha, that might be.  My apologies -- I play in ACPI but seldom in the network
drivers, so was not fully aware of that change.  I can give that a try.

Thanks for the pointer.

-- 
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Red Hat, Inc.
ahs3@...hat.com
-----------------------------------