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Date:   Wed, 11 Apr 2018 10:17:24 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Jia-Ju Bai <baijiaju1990@gmail.com>
Cc:     devel@driverdev.osuosl.org, samuel@sortiz.org,
        netdev@vger.kernel.org, johan@kernel.org,
        linux-kernel@vger.kernel.org, arvind.yadav.cs@gmail.com,
        davem@davemloft.net
Subject: Re: [PATCH 1/2] staging: irda: Replace mdelay with usleep_range in
 stir421x_fw_upload
Message-ID: <20180411081724.GA4155@kroah.com>
References: <1523410174-1553-1-git-send-email-baijiaju1990@gmail.com>
 <20180411064135.GA28354@kroah.com>
 <d65d1116-7ffd-e289-5379-cc052782700d@gmail.com>
 <20180411080311.GB2137@kroah.com>
 <ecf21a6e-0e99-55dc-54be-3bd633bedbc5@gmail.com>
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On Wed, Apr 11, 2018 at 04:11:00PM +0800, Jia-Ju Bai wrote:
> 
> 
> On 2018/4/11 16:03, Greg KH wrote:
> > On Wed, Apr 11, 2018 at 03:17:10PM +0800, Jia-Ju Bai wrote:
> > > 
> > > On 2018/4/11 14:41, Greg KH wrote:
> > > > On Wed, Apr 11, 2018 at 09:29:34AM +0800, Jia-Ju Bai wrote:
> > > > > stir421x_fw_upload() is never called in atomic context.
> > > > > 
> > > > > The call chain ending up at stir421x_fw_upload() is:
> > > > > [1] stir421x_fw_upload() <- stir421x_patch_device() <- irda_usb_probe()
> > > > > 
> > > > > irda_usb_probe() is set as ".probe" in struct usb_driver.
> > > > > This function is not called in atomic context.
> > > > > 
> > > > > Despite never getting called from atomic context, stir421x_fw_upload()
> > > > > calls mdelay() to busily wait.
> > > > > This is not necessary and can be replaced with usleep_range() to
> > > > > avoid busy waiting.
> > > > > 
> > > > > This is found by a static analysis tool named DCNS written by myself.
> > > > > And I also manually check it.
> > > > > 
> > > > > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
> > > > > ---
> > > > >    drivers/staging/irda/drivers/irda-usb.c | 2 +-
> > > > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > > > Please, at the very least, work off of Linus's tree.  There is no
> > > > drivers/staging/irda/ anymore :)
> > > > 
> > > Okay, sorry.
> > > Could you please recommend me a right tree or its git address?
> > Have you looked in the MAINTAINERS file?  Worst case, always use
> > linux-next.
> > 
> > greg k-h
> 
> Oh, sorry, I did notice the git tree in the MAINTAINERS file.
> I always used linux-stable.

linux-stable is almost never the tree to use as it is almost always
12000 patches behind what is in Linus's tree and about 20000 changes
behind linux-next.

thanks,

greg k-h