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Date: Wed, 31 Jul 2024 11:16:00 +0200
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Michael Walle <mwalle@kernel.org>
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] usb: gadget: f_acm: make bInterfaceProtocol configurable
Message-ID: <2024073145-treat-winnings-3bb4@gregkh>
References: <20240730194337.2583784-1-mwalle@kernel.org>
 <2024073151-violator-unskilled-6866@gregkh>
 <D33LLE6K8QGH.1BCZM42INRVEX@kernel.org>
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On Wed, Jul 31, 2024 at 10:57:04AM +0200, Michael Walle wrote:
> Hi Greg,
> 
> On Wed Jul 31, 2024 at 10:32 AM CEST, Greg Kroah-Hartman wrote:
> > On Tue, Jul 30, 2024 at 09:43:37PM +0200, Michael Walle wrote:
> > >  struct f_serial_opts {
> > >  	struct usb_function_instance func_inst;
> > >  	u8 port_num;
> > > +	u8 protocol;
> > > +
> > > +	struct mutex lock;
> > > +	int refcnt;
> >
> > Attempting to "roll your own" reference count is almost never a good
> > idea.  If you really need one, please use the proper in-kernel apis for
> > this.  But you need to justify it as well, I didn't see why this was
> > needed at all.
> 
> Honestly, I couldn't grok all that usb gadget magic, so I've looked
> at similar gadgets and took that from there:
>   grep refcnt drivers/usb/gadget/function/ -r
> 
> They are all doing the same, so maybe that code is old or didn't use
> the proper APIs back then.

It's old code, please do things properly.

thanks,

greg k-h