netdev - Re: [PATCH 1/2] staging: irda: Replace mdelay with usleep_range in stir421x_fw

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Message-ID: <20180411081724.GA4155@kroah.com>
Date:   Wed, 11 Apr 2018 10:17:24 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     devel@...verdev.osuosl.org, samuel@...tiz.org,
        netdev@...r.kernel.org, johan@...nel.org,
        linux-kernel@...r.kernel.org, arvind.yadav.cs@...il.com,
        davem@...emloft.net
Subject: Re: [PATCH 1/2] staging: irda: Replace mdelay with usleep_range in
 stir421x_fw_upload

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@...il.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