linux-kernel - Re: [PATCH] kernel: x86: tboot: Replace mdelay with usleep_range in tboot_wait_for

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Message-ID: <fc5e01ed-e360-5d48-01ea-dbcafb6cf7f9@gmail.com>
Date:   Wed, 24 Jan 2018 21:37:46 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     ning.sun@...el.com, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, tboot-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kernel: x86: tboot: Replace mdelay with usleep_range in
 tboot_wait_for_aps


On 2018/1/24 19:47, Thomas Gleixner wrote:
> On Wed, 24 Jan 2018, Jia-Ju Bai wrote:
>
>> The function tboot_wait_for_aps is not called in atomic context.
>> Thus mdelay can be replaced with usleep_range, to reduce busy wait.
> And how did you establish that it's not called in atomic context?
>
> Thanks,
>
> 	tglx

It is reported by a static analysis tool written by myself.
This tool finds that mdelay in tboot_wait_for_aps is not called by 
holding a spinlock or in an interrupt handler, thus mdelay can be replaced.


Thanks,
Jia-Ju Bai