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Date: Wed, 13 Jan 2016 23:41:37 +0300
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Felipe Ferreri Tonello <eu@felipetonello.com>
Cc: Michal Nazarewicz <mina86@mina86.com>, Felipe Balbi <balbi@ti.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Robert Baldyga <r.baldyga@samsung.com>,
        Andrzej Pietrasiewicz <andrzej.p@samsung.com>,
        Pawel Szewczyk <p.szewczyk@samsung.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv2 1/2] usb: gadget: f_midi: use flexible array member for
 gmidi_in_port elements
Message-ID: <20160113204137.GC4399@mwanda>
References: <1452311230-21431-1-git-send-email-mina86@mina86.com>
 <569696CE.1000707@felipetonello.com>
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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