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Date: Tue, 14 Apr 2015 15:53:49 +0800
From: Ding Tianhong <dingtianhong@huawei.com>
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To: Thomas Gleixner <tglx@linutronix.de>, Arnd Bergmann <arnd@arndb.de>
CC: LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Zhangfei Gao <zhangfei.gao@linaro.org>,
        Dan Carpenter <dan.carpenter@oracle.com>, <netdev@vger.kernel.org>
Subject: Re: [patch 4/5] net: hip04: Make tx coalesce timer actually work
References: <20150413210009.682000343@linutronix.de> <9614284.QjZ4xls6zV@wuerfel> <alpine.DEB.2.11.1504132338080.3845@nanos> <3040901.Bp3bfgc1te@wuerfel> <alpine.DEB.2.11.1504140007570.3845@nanos>
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On 2015/4/14 6:08, Thomas Gleixner wrote:
> On Tue, 14 Apr 2015, Arnd Bergmann wrote:
>> On Monday 13 April 2015 23:42:03 Thomas Gleixner wrote:
>>>>
>>>> Question: this looks to me like it sets both the minimum and maximum
>>>> time to priv->tx_coalesce_usecs/2, when the intention was to set
>>>> the minimum to priv->tx_coalesce_usecs/2 and the maximum to
>>>> priv->tx_coalesce_usecs. Am I missing something subtle here, or did
>>>> you just misread my original intention from the botched code?
>>>
>>> Yes, I missed that. Simple fix for this is:
>>>
>>>   unsigned long t_ns = priv->tx_coalesce_usecs * NSEC_PER_USEC / 2;
>>>   
>>>   hrtimer_start_range_ns(&priv->tx_coalesce_timer, ns_to_ktime(t_ns),
>>>                          t_ns, HRTIMER_MODE_REL);
>>
>> Ah, good. I have to admit that I'd probably make the same mistake
>> again if I was to do this for another driver and you hadn't sent
>> the fix. The hrtimer_set_expires_range() function just looked like
>> it had been designed for the use case I was interested in ;-).
>>
>> Any idea how to prevent the next person from making the same mistake?
> 
> Yes. Documentation :)
> 
Looks good to me, thanks everyone.

Ding

> Thanks,
> 
> 	tglx
> 
> .
>