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From: "Lendacky, Thomas" <Thomas.Lendacky@amd.com>
To: David Miller <davem@davemloft.net>, "ahs3@redhat.com" <ahs3@redhat.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"isubramanian@apm.com" <isubramanian@apm.com>,
	"kchudgar@apm.com" <kchudgar@apm.com>,
	"qnguyen@apm.com" <qnguyen@apm.com>
Subject: Re: [PATCH] net: apm: xgene: force XGene enet driver to re-balance IRQ usage
Date: Tue, 18 Sep 2018 23:09:57 +0000	[thread overview]
Message-ID: <a5adee73-dde7-d00f-e7ef-1f81dc7c813a@amd.com> (raw)
In-Reply-To: <20180917.193531.1424852853827678152.davem@davemloft.net>



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.
> 

  parent reply	other threads:[~2018-09-18 23:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-17 23:35 [PATCH] net: apm: xgene: force XGene enet driver to re-balance IRQ usage Al Stone
2018-09-18  2:35 ` David Miller
2018-09-18 20:21   ` Al Stone
2018-09-18 23:09   ` Lendacky, Thomas [this message]
2018-09-18 23:15     ` Al Stone
2018-09-18 23:21       ` Florian Fainelli
2018-09-18 23:27         ` Eric Dumazet
2018-09-18 23:56           ` Eric Dumazet
2018-09-19  0:03             ` Florian Fainelli
2018-09-19  2:32               ` Eric Dumazet
2018-09-18 23:25       ` Eric Dumazet

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