linux-kernel - Re: [PATCH 3/3] [media] cx231xx: only unregister successfully registered i2c adapters

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Message-ID: <24c02947-3812-1a1b-f6b7-dc5a3ff69d66@axentia.se>
Date:   Wed, 9 Aug 2017 16:43:03 +0200
From:   Peter Rosin <peda@...ntia.se>
To:     Mauro Carvalho Chehab <mchehab@...pensource.com>
Cc:     linux-kernel@...r.kernel.org,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org
Subject: Re: [PATCH 3/3] [media] cx231xx: only unregister successfully
 registered i2c adapters

On 2017-08-09 16:27, Mauro Carvalho Chehab wrote:
> Em Mon, 31 Jul 2017 15:38:52 +0200
> Peter Rosin <peda@...ntia.se> escreveu:
> 
>> This prevents potentially scary debug messages from the i2c core.
>>
>> Signed-off-by: Peter Rosin <peda@...ntia.se>
>> ---
>>  drivers/media/usb/cx231xx/cx231xx-core.c | 3 +++
>>  drivers/media/usb/cx231xx/cx231xx-i2c.c  | 3 ++-
>>  2 files changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/usb/cx231xx/cx231xx-core.c b/drivers/media/usb/cx231xx/cx231xx-core.c
>> index 46646ecd2dbc..f372ad3917a8 100644
>> --- a/drivers/media/usb/cx231xx/cx231xx-core.c
>> +++ b/drivers/media/usb/cx231xx/cx231xx-core.c
>> @@ -1311,6 +1311,7 @@ int cx231xx_dev_init(struct cx231xx *dev)
>>  	dev->i2c_bus[0].i2c_period = I2C_SPEED_100K;	/* 100 KHz */
>>  	dev->i2c_bus[0].i2c_nostop = 0;
>>  	dev->i2c_bus[0].i2c_reserve = 0;
>> +	dev->i2c_bus[0].i2c_rc = -ENODEV;
>>  
>>  	/* External Master 2 Bus */
>>  	dev->i2c_bus[1].nr = 1;
>> @@ -1318,6 +1319,7 @@ int cx231xx_dev_init(struct cx231xx *dev)
>>  	dev->i2c_bus[1].i2c_period = I2C_SPEED_100K;	/* 100 KHz */
>>  	dev->i2c_bus[1].i2c_nostop = 0;
>>  	dev->i2c_bus[1].i2c_reserve = 0;
>> +	dev->i2c_bus[1].i2c_rc = -ENODEV;
>>  
>>  	/* Internal Master 3 Bus */
>>  	dev->i2c_bus[2].nr = 2;
>> @@ -1325,6 +1327,7 @@ int cx231xx_dev_init(struct cx231xx *dev)
>>  	dev->i2c_bus[2].i2c_period = I2C_SPEED_100K;	/* 100kHz */
>>  	dev->i2c_bus[2].i2c_nostop = 0;
>>  	dev->i2c_bus[2].i2c_reserve = 0;
>> +	dev->i2c_bus[2].i2c_rc = -ENODEV;
>>  
>>  	/* register I2C buses */
>>  	errCode = cx231xx_i2c_register(&dev->i2c_bus[0]);
>> diff --git a/drivers/media/usb/cx231xx/cx231xx-i2c.c b/drivers/media/usb/cx231xx/cx231xx-i2c.c
>> index 3e49517cb5e0..8ce6b815d16d 100644
>> --- a/drivers/media/usb/cx231xx/cx231xx-i2c.c
>> +++ b/drivers/media/usb/cx231xx/cx231xx-i2c.c
>> @@ -553,7 +553,8 @@ int cx231xx_i2c_register(struct cx231xx_i2c *bus)
>>   */
>>  void cx231xx_i2c_unregister(struct cx231xx_i2c *bus)
>>  {
>> -	i2c_del_adapter(&bus->i2c_adap);
>> +	if (!bus->i2c_rc)
>> +		i2c_del_adapter(&bus->i2c_adap);
> 
> That doesn't sound right. what happens if i2c_rc is 1 or 2?
> 
> IMHO, the right would would be, instead:
> 
> 	if (bus->i2c_rc >= 0)
> 		i2c_del_adapter(&bus->i2c_adap);

In theory, yes. But in practice i2c_add_adapter never returns >0, and is
also documented so.

Let me know if you still want an update. In that case I'll also fix the
precedent present in the context of patch 1/3, i.e.

	if (0 != bus->i2c_rc)
		...

Cheers,
peda