Re: [PATCH] i2c: i2c-core: do not use bus internal data

Sudip Mukherjee
2016-03-07T17:18:14Z

On Monday 07 March 2016 10:27 PM, Greg KH wrote:
> On Mon, Mar 07, 2016 at 05:19:17PM +0530, Sudip Mukherjee wrote:
>> The variable p is a data structure which is used by the driver core
>> internally and it is not expected that busses will be directly accessing
>> these driver core internal only data.
>>
>> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
>> ---
>>
>> Reference of Greg's comment about it at:
>> https://lkml.org/lkml/2016/3/5/171
>>
>> drivers/i2c/i2c-core.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
>> index 2949ab3..2f31fb5 100644
>> --- a/drivers/i2c/i2c-core.c
>> +++ b/drivers/i2c/i2c-core.c
>> @@ -73,6 +73,7 @@ static struct device_type i2c_client_type;
>> static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
>>
>> static struct static_key i2c_trace_msg = STATIC_KEY_INIT_FALSE;
>> +static bool is_registered;
>>
>> void i2c_transfer_trace_reg(void)
>> {
>> @@ -1529,7 +1530,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
>> int res = 0;
>>
>> /* Can't register until after driver model init */
>> - if (unlikely(WARN_ON(!i2c_bus_type.p))) {
>> + if (unlikely(WARN_ON(!is_registered))) {
>> res = -EAGAIN;
>> goto out_list;
>> }
>
> Minor nit, likely/unlikely should only be used on very "hot paths" where
> the difference if it is not included can be measured. the "register a
> device" path is not "hot" at all.

I can submit a patch afterwards to remove the "unlikely" if that is ok
with Wolfram.

regards
sudip