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([2a01:110f:b59:fd00:c94a:5ae2:2301:3939]) by smtp.gmail.com with ESMTPSA id j6sm4508849edy.87.2020.11.01.08.40.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 01 Nov 2020 08:40:11 -0800 (PST) Subject: Re: [PATCH RFC leds + net-next 2/7] leds: trigger: netdev: simplify the driver by using bit field members To: =?UTF-8?Q?Marek_Beh=c3=ban?= Cc: netdev@vger.kernel.org, linux-leds@vger.kernel.org, Pavel Machek , Dan Murphy , Russell King , Andrew Lunn , Matthias Schiffer , "David S. Miller" , Ben Whitten References: <20201030114435.20169-1-kabel@kernel.org> <20201030114435.20169-3-kabel@kernel.org> <64419e33-ffcd-4082-01bd-3370dae86b4b@gmail.com> <20201031004556.32c61a9d@kernel.org> From: Jacek Anaszewski Message-ID: Date: Sun, 1 Nov 2020 17:40:08 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201031004556.32c61a9d@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 10/31/20 12:45 AM, Marek Behún wrote: > On Fri, 30 Oct 2020 23:37:52 +0100 > Jacek Anaszewski wrote: > >> Hi Marek, >> >> Bitops are guaranteed to be atomic and this was done for a reason. > > Hmm okay... > Sooo, netdev_trig_work cannot be executed at the same time as the > link/linkup/rx/tx changing stuff from netdev_trig_notify, > interval_store or netdev_led_attr_store, because all these functions > ensure cancelation of netdev_trig_work by calling > cancel_delayed_work_sync. Doesn't this somehow prevent the need for > memory barriers provided by atomic bitops? That's true. But unless there is proven decline in performance related to use of bitops, I don't see any gain in removing those from this trigger. They improve code readability. > BTW Jacek what do you think about the other patches? I like the idea, but I'd need to spend more time reviewing it. One thing coming to mind at first glance - it would be good to get rid of blink_set op at this occasion since this is just another case of trigger offloading. It would however need touching many drivers, so that could possibly be done as a follow-up. -- Best regards, Jacek Anaszewski