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[2003:ea:8f06:ee00:bcdf:534e:d44f:409]) by smtp.googlemail.com with ESMTPSA id d13sm1104293wmb.39.2020.05.01.14.29.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 01 May 2020 14:29:22 -0700 (PDT) Subject: [PATCH net-next 1/2] timer: add fsleep for flexible sleeping From: Heiner Kallweit To: Thomas Gleixner , Jonathan Corbet , Realtek linux nic maintainers , David Miller Cc: "netdev@vger.kernel.org" , Linux Kernel Mailing List , linux-doc@vger.kernel.org References: <8e3c56ca-b43f-3877-0104-a1a279d5a6c5@gmail.com> Message-ID: <5e3c3f78-344c-ae03-b6ae-ea55e402c1e7@gmail.com> Date: Fri, 1 May 2020 23:27:21 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <8e3c56ca-b43f-3877-0104-a1a279d5a6c5@gmail.com> 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 Sleeping for a certain amount of time requires use of different functions, depending on the time period. Documentation/timers/timers-howto.rst explains when to use which function, and also checkpatch checks for some potentially problematic cases. So let's create a helper that automatically chooses the appropriate sleep function -> fsleep(), for flexible sleeping If the delay is a constant, then the compiler should be able to ensure that the new helper doesn't create overhead. If the delay is not constant, then the new helper can save some code. Signed-off-by: Heiner Kallweit --- Documentation/timers/timers-howto.rst | 3 +++ include/linux/delay.h | 11 +++++++++++ 2 files changed, 14 insertions(+) diff --git a/Documentation/timers/timers-howto.rst b/Documentation/timers/timers-howto.rst index 7e3167bec..afb0a43b8 100644 --- a/Documentation/timers/timers-howto.rst +++ b/Documentation/timers/timers-howto.rst @@ -110,3 +110,6 @@ NON-ATOMIC CONTEXT: short, the difference is whether the sleep can be ended early by a signal. In general, just use msleep unless you know you have a need for the interruptible variant. + + FLEXIBLE SLEEPING (any delay, uninterruptible) + * Use fsleep diff --git a/include/linux/delay.h b/include/linux/delay.h index 8e6828094..cb1d508ca 100644 --- a/include/linux/delay.h +++ b/include/linux/delay.h @@ -65,4 +65,15 @@ static inline void ssleep(unsigned int seconds) msleep(seconds * 1000); } +/* see Documentation/timers/timers-howto.rst for the thresholds */ +static inline void fsleep(unsigned long usecs) +{ + if (usecs <= 10) + udelay(usecs); + else if (usecs <= 20000) + usleep_range(usecs, 2 * usecs); + else + msleep(DIV_ROUND_UP(usecs, 1000)); +} + #endif /* defined(_LINUX_DELAY_H) */ -- 2.26.2