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Date: Fri, 12 Jan 2024 09:26:54 +0100
From: Greg KH <gregkh@linuxfoundation.org>
To: Xu Yang <xu.yang_2@nxp.com>
Cc: benjamin.tissoires@redhat.com, hdegoede@redhat.com,
	ivan.orlov0322@gmail.com, heikki.krogerus@linux.intel.com,
	linux-usb@vger.kernel.org, linux-imx@nxp.com, jun.li@nxp.com
Subject: Re: [PATCH] usb: roles: try to get/put all relevant modules
Message-ID: <2024011220-asleep-dragster-1e39@gregkh>
References: <20240112080108.1147450-1-xu.yang_2@nxp.com>
 <2024011213-situated-augmented-64a4@gregkh>
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In-Reply-To: <2024011213-situated-augmented-64a4@gregkh>

On Fri, Jan 12, 2024 at 09:24:11AM +0100, Greg KH wrote:
> On Fri, Jan 12, 2024 at 04:01:08PM +0800, Xu Yang wrote:
> > +void usb_role_switch_get_modules(struct device *dev)
> > +{
> > +	while (dev) {
> > +		if (dev->driver)
> > +			WARN_ON(!try_module_get(dev->driver->owner));
> 
> You just crashed all systems that have panic-on-warn enabled, which is
> by far (i.e. in the billions) the huge majority of Linux systems in the
> world.
> 
> If this is something that can fail, then properly handle the issue,
> don't just give up and say "let's fill the kernel log with a mess and
> reboot the box!".

Ah, I see now you are just moving the code, but please, let's fix this
properly, don't persist in the wrong code here.

thanks,

greg k-h