linux-kernel - Re: [PATCH] Input: LEDs

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Message-ID: <20150723212254.GA25053@amd>
Date:	Thu, 23 Jul 2015 23:22:54 +0200
From:	Pavel Machek <pavel@....cz>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Vlastimil Babka <vbabka@...e.cz>, Jiri Kosina <jkosina@...e.com>,
	Samuel Thibault <samuel.thibault@...-lyon.org>,
	Pali Rohár <pali.rohar@...il.com>,
	linux-input@...r.kernel.org, rpurdie@...ys.net,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: LEDs - skip unnamed LEDs

On Thu 2015-07-23 13:57:13, Dmitry Torokhov wrote:
> On Thu, Jul 23, 2015 at 08:19:13AM +0200, Pavel Machek wrote:
> > On Wed 2015-07-22 15:02:02, Dmitry Torokhov wrote:
> > > Devices may declare more LEDs than what is known to input-leds
> > > (HID does this for some devices). Instead of showing ugly warnings
> > > on connect and, even worse, oopsing on disconnect, let's simply
> > > ignore LEDs that are not known to us.
> > > 
> > > Reported-by: Vlastimil Babka <vbabka@...e.cz>
> > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > > ---
> > >  drivers/input/input-leds.c |   16 ++++++++++++++--
> > >  1 file changed, 14 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/input/input-leds.c b/drivers/input/input-leds.c
> > > index 074a65e..766bf26 100644
> > > --- a/drivers/input/input-leds.c
> > > +++ b/drivers/input/input-leds.c
> > > @@ -71,6 +71,18 @@ static void input_leds_event(struct input_handle *handle, unsigned int type,
> > >  {
> > >  }
> > >  
> > > +static int input_leds_get_count(struct input_dev *dev)
> > > +{
> > > +	unsigned int led_code;
> > > +	int count = 0;
> > > +
> > > +	for_each_set_bit(led_code, dev->ledbit, LED_CNT)
> > > +		if (input_led_info[led_code].name)
> > > +			count++;
> > > +
> > > +	return count;
> > > +}
> > > +
> > >  static int input_leds_connect(struct input_handler *handler,
> > >  			      struct input_dev *dev,
> > >  			      const struct input_device_id *id)
> > > @@ -81,7 +93,7 @@ static int input_leds_connect(struct input_handler *handler,
> > >  	int led_no;
> > >  	int error;
> > >  
> > > -	num_leds = bitmap_weight(dev->ledbit, LED_CNT);
> > > +	num_leds = input_leds_get_count(dev);
> > >  	if (!num_leds)
> > >  		return -ENXIO;
> > >  
> > > @@ -112,7 +124,7 @@ static int input_leds_connect(struct input_handler *handler,
> > >  		led->handle = &leds->handle;
> > >  		led->code = led_code;
> > >  
> > > -		if (WARN_ON(!input_led_info[led_code].name))
> > > +		if (!input_led_info[led_code].name)
> > >  			continue;
> > >  
> > >  		led->cdev.name = kasprintf(GFP_KERNEL, "%s::%s",
> > >
> > 
> > Are you sure? AFAICT you need to fix err_unregister_leds not to
> > unregister leds with no name...
> 
> Well, if we skip unnamed leds and do not include them into total count
> then we won't need to unregister them.

I don't get it.

If there's unnamed led at index 0, and named one at indexes 1 and
2.. and there's -ENOMEM registering 2, it will try to unregister leds
0 and 1, and crash, no?
								Pavel

-- 
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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