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

[Sudip Mukherjee]

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@xxxxxxxxxxxxxxx>
> > ---
> >
> > 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