linux-kernel - Re: [PATCH] ata: pata_it821x: Replace mdelay with usleep_range in it821x_firmware

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Message-ID: <20180125153115.GF17457@devbig577.frc2.facebook.com>
Date:   Thu, 25 Jan 2018 07:31:15 -0800
From:   Tejun Heo <tj@...nel.org>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     b.zolnierkie@...sung.com, linux-ide@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ata: pata_it821x: Replace mdelay with usleep_range in
 it821x_firmware_command

On Thu, Jan 25, 2018 at 06:32:59PM +0800, Jia-Ju Bai wrote:
> After checking all possible call chains to it821x_firmware_command here,
> my tool finds that it821x_firmware_command 
> is never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> And it821x_firmware_command calls kmalloc(GFP_KERNEL), 
> so it proves again that it821x_firmware_command 
> can call functions which can sleep.
> Thus mdelay can be replaced with usleep_range to avoid busy wait.
> 
> This is found by a static analysis tool named DCNS written by myself.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>

Applied to libata/for-4.16.

Thanks.

-- 
tejun