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Date:   Thu, 23 Jun 2022 07:53:12 +0200
From:   Johan Hovold <johan@kernel.org>
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] Input: usbtouchscreen - suppress empty array warnings
Message-ID: <YrP/yOkM0q877HGu@hovoldconsulting.com>
References: <20220620084628.20894-1-johan@kernel.org>
 <20220620084628.20894-2-johan@kernel.org>
 <YrOkIMJK3G3VkhLk@google.com>
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On Wed, Jun 22, 2022 at 04:22:08PM -0700, Dmitry Torokhov wrote:
> Hi Johan,
> 
> On Mon, Jun 20, 2022 at 10:46:27AM +0200, Johan Hovold wrote:
> > When compile-testing the USB touchscreen driver without enabling any of
> > the device type options the usbtouch_dev_info array ends up being empty,
> > something which triggers compiler warning with -Warray-bounds
> > (gcc-11.3.0).
> > 
> > drivers/input/touchscreen/usbtouchscreen.c: In function 'usbtouch_probe':
> > drivers/input/touchscreen/usbtouchscreen.c:1668:16:warning: array subscript <unknown> is outside array bounds of 'struct usbtouch_device_info[0]' [-Warray-bounds]
> >  1668 |         type = &usbtouch_dev_info[id->driver_info];
> > 
> > Suppress the warnings by making sure that the array is always non-empty.
> 
> Does it still warn if you add a check for type, something like
> 
> 	if (type >= ARRAY_SIZE(usbtouch_device_info))
> 		return -ENODEV;
> 
> ?

It seems 

	if (id->driver_info >= ARRAY_SIZE(usbtouch_dev_info))
                return -ENODEV;

indeed does the trick. I'll send a v2.

Johan