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([2620:15c:2c1:200:55c7:81e6:c7d8:94b]) by smtp.gmail.com with ESMTPSA id z22-v6sm26992542pgc.67.2018.09.18.16.27.29 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 18 Sep 2018 16:27:29 -0700 (PDT) Subject: Re: [PATCH] net: apm: xgene: force XGene enet driver to re-balance IRQ usage To: Florian Fainelli , ahs3@redhat.com, "Lendacky, Thomas" , David Miller Cc: "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "isubramanian@apm.com" , "kchudgar@apm.com" , "qnguyen@apm.com" References: <20180917233533.28626-1-ahs3@redhat.com> <20180917.193531.1424852853827678152.davem@davemloft.net> <4929e93d-508a-4670-9450-66e4fc85be7e@redhat.com> From: Eric Dumazet Message-ID: Date: Tue, 18 Sep 2018 16:27:28 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/18/2018 04:21 PM, Florian Fainelli wrote: > On 09/18/2018 04:15 PM, Al Stone wrote: >> On 09/18/2018 05:09 PM, Lendacky, Thomas wrote: >>> >>> >>> On 09/17/2018 09:35 PM, David Miller wrote: >>>> From: Al Stone >>>> 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. > > FWIW this is being discussed in this thread as well: > > https://www.spinics.net/lists/netdev/msg523760.html > > there should be an update to drivers that have a ndo_poll_controller() > and don't check napi_complete_done(), though I am not clear who is doing > that yet. That might be tricky. I remember one of the napi_complete_done() change had to be reverted, for some obscure reason. So clearly, doing a mass update (without being able to test the driver on real hardware) might be risky.