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(p200300ea8f0655007ca20fb69bdef4e5.dip0.t-ipconnect.de. [2003:ea:8f06:5500:7ca2:fb6:9bde:f4e5]) by smtp.googlemail.com with ESMTPSA id j10sm869109wmj.7.2021.01.11.13.35.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Jan 2021 13:35:58 -0800 (PST) To: Paul Thomas , Nicolas Ferre , Claudiu Beznea , "David S. Miller" , Jakub Kicinski , Russell King , Palmer Dabbelt , Paul Walmsley , netdev@vger.kernel.org, linux-kernel , linux-riscv@lists.infradead.org References: From: Heiner Kallweit Subject: Re: net: macb: can macb use __napi_schedule_irqoff() instead of __napi_schedule() Message-ID: Date: Mon, 11 Jan 2021 22:35:54 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11.01.2021 20:45, Paul Thomas wrote: > Hello, recently I was doing a lot of tracing/profiling to understand > an issue we were having. Anyway, during this I ran across > __napi_schedule_irqoff() where the comment in dev.c says "Variant of > __napi_schedule() assuming hard irqs are masked". > > It looks like the queue_writel(queue, IDR, bp->rx_intr_mask); call > just before the __napi_schedule() call in macb_main.c is doing this > hard irq masking? So could it change to be like this? > It's unsafe under forced irq threading. There has been a number of discussions about this topic in the past. > --- a/drivers/net/ethernet/cadence/macb_main.c > +++ b/drivers/net/ethernet/cadence/macb_main.c > @@ -1616,7 +1623,7 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id) > > if (napi_schedule_prep(&queue->napi)) { > netdev_vdbg(bp->dev, "scheduling RX softirq\n"); > - __napi_schedule(&queue->napi); > + __napi_schedule_irqoff(&queue->napi); > } > } > > -Paul >