linux-kernel - Re: [PATCHv2 1/2] usb: gadget: f_midi: use flexible array member for gmidi_in

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Message-ID: <20160113204137.GC4399@mwanda>
Date:	Wed, 13 Jan 2016 23:41:37 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Felipe Ferreri Tonello <eu@...ipetonello.com>
Cc:	Michal Nazarewicz <mina86@...a86.com>, Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Robert Baldyga <r.baldyga@...sung.com>,
	Andrzej Pietrasiewicz <andrzej.p@...sung.com>,
	Pawel Szewczyk <p.szewczyk@...sung.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 1/2] usb: gadget: f_midi: use flexible array member for
 gmidi_in_port elements

On Wed, Jan 13, 2016 at 06:26:22PM +0000, Felipe Ferreri Tonello wrote:
> > @@ -1115,26 +1112,16 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
> >  	}
> >  
> >  	/* allocate and initialize one new instance */
> > -	midi = kzalloc(sizeof(*midi), GFP_KERNEL);
> > +	midi = kzalloc(
> > +		sizeof(*midi) + opts->in_ports * sizeof(*midi->in_ports_array),
> > +		GFP_KERNEL);
> 
> Is there a garantee that the compiler will always use in_ports_array at
> the end of the allocated block?
> 

Yes.  It's fine.  Zero size arrays at the end of a struct are normal.

regards,
dan carpenter