linux-kernel - Re: [PATCH 1/2] hp100: Fix a possible sleep-in-atomic bug in hp100_login_to_vg

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Message-ID: <4d287eef-76ad-3379-af6b-858bf497e515@gmail.com>
Date:   Thu, 14 Dec 2017 11:31:06 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     perex@...ex.cz, floeff@...hematik.uni-stuttgart.de,
        acme@...ectiva.com.br, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] hp100: Fix a possible sleep-in-atomic bug in
 hp100_login_to_vg_hub

Sorry, I made a mistake in last e-mail.

Maybe "mdelay(1000/HZ)" or "udelay(1000000/HZ)" .
Which one do you think is right?


Thanks,
Jia-Ju Bai

On 2017/12/14 11:13, Jia-Ju Bai wrote:
> Thanks for reply :)
> I think I should use "udelay(100000/HZ)" instead, do you think it is 
> right?
>
>
> Thanks,
> Jia-Ju Bai
>
>
> On 2017/12/14 5:20, David Miller wrote:
>> I want you to review all of your patches and resend them after you
>> have checked them carefully.
>>
>> The first patch I even looked at, this one, is buggy.
>>
>> You changed a schedule_timeout_interruptible(1) into a udelay(10)
>>
>> That's not right.
>>
>> schedule_timeout_interruptible() takes a "jiffies" argument, which
>> is a completely different unit than udelay() takes.  You would have
>> to scale the argument to udelay() in some way using HZ.
>>
>> Furthermore, the udelay argument you would come up with would
>> be way too long to be appropirate in this atomic context.
>>
>> That's why the code tries to use a sleeping timeout, a long wait is
>> necessary here.
>