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[73.241.150.58]) by smtp.gmail.com with ESMTPSA id x127sm21687362pfd.86.2020.08.17.17.33.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Aug 2020 17:33:53 -0700 (PDT) Subject: Re: [PATCH 3/3] net: lantiq: Use napi_complete_done() To: Hauke Mehrtens , Eric Dumazet , davem@davemloft.net Cc: kuba@kernel.org, netdev@vger.kernel.org, martin.blumenstingl@googlemail.com References: <20200815183314.404-1-hauke@hauke-m.de> <20200815183314.404-3-hauke@hauke-m.de> <17761534-65b1-e575-5e00-55e6f7e3f7b7@gmail.com> <718dce81-ace3-aaad-0f81-e75e227cd722@hauke-m.de> From: Eric Dumazet Message-ID: <28b6bd3f-761c-9143-e90d-30af5d76e3ed@gmail.com> Date: Mon, 17 Aug 2020 17:33:52 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <718dce81-ace3-aaad-0f81-e75e227cd722@hauke-m.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 8/17/20 2:17 PM, Hauke Mehrtens wrote: > On 8/16/20 8:07 PM, Eric Dumazet wrote: >> >> >> On 8/15/20 11:33 AM, Hauke Mehrtens wrote: >>> Use napi_complete_done() and activate the interrupts when this function >>> returns true. This way the generic NAPI code can take care of activating >>> the interrupts. >>> >>> Signed-off-by: Hauke Mehrtens >>> --- >>> drivers/net/ethernet/lantiq_xrx200.c | 8 ++------ >>> 1 file changed, 2 insertions(+), 6 deletions(-) >>> >>> diff --git a/drivers/net/ethernet/lantiq_xrx200.c b/drivers/net/ethernet/lantiq_xrx200.c >>> index f34e4dc8c661..674ffb2ecd9a 100644 >>> --- a/drivers/net/ethernet/lantiq_xrx200.c >>> +++ b/drivers/net/ethernet/lantiq_xrx200.c >>> @@ -229,10 +229,8 @@ static int xrx200_poll_rx(struct napi_struct *napi, int budget) >>> } >>> } >>> >>> - if (rx < budget) { >>> - napi_complete(&ch->napi); >>> + if (napi_complete_done(&ch->napi, rx)) >>> ltq_dma_enable_irq(&ch->dma); >>> - } >>> >>> return rx; >>> } >>> @@ -271,10 +269,8 @@ static int xrx200_tx_housekeeping(struct napi_struct *napi, int budget) >>> if (netif_queue_stopped(net_dev)) >>> netif_wake_queue(net_dev); >>> >>> - if (pkts < budget) { >>> - napi_complete(&ch->napi); >>> + if (napi_complete_done(&ch->napi, pkts)) >>> ltq_dma_enable_irq(&ch->dma); >>> - } >>> >>> return pkts; >>> } >>> >> >> >> This looks buggy to me. > > Hi Eric, > > Thanks for looking at the patch. > > What exactly looks buggy to you? You removed the " if (rx < budget) " But you must not. Drivers have to keep the test. Something like that seems more correct : diff --git a/drivers/net/ethernet/lantiq_xrx200.c b/drivers/net/ethernet/lantiq_xrx200.c index 1645e4e7ebdbb3c7abff8fe4207273df20f123d4..e3d617d387ed0f5593c3ba81d1d531d463bb5a6e 100644 --- a/drivers/net/ethernet/lantiq_xrx200.c +++ b/drivers/net/ethernet/lantiq_xrx200.c @@ -230,8 +230,8 @@ static int xrx200_poll_rx(struct napi_struct *napi, int budget) } if (rx < budget) { - napi_complete(&ch->napi); - ltq_dma_enable_irq(&ch->dma); + if (napi_complete(&ch->napi, rx)) + ltq_dma_enable_irq(&ch->dma); } return rx; @@ -269,8 +269,8 @@ static int xrx200_tx_housekeeping(struct napi_struct *napi, int budget) netdev_completed_queue(ch->priv->net_dev, pkts, bytes); if (pkts < budget) { - napi_complete(&ch->napi); - ltq_dma_enable_irq(&ch->dma); + if (napi_complete(&ch->napi, pkts)) + ltq_dma_enable_irq(&ch->dma); } return pkts;