Re: [PATCH 3/3] i2c: muxes: i2c-mux-gpmux: Use of_get_i2c_adapter_by_node()

[Herve Codina]

Hi Peter,

On Thu, 19 Oct 2023 11:26:41 +0200
Peter Rosin <peda@xxxxxxxxxx> wrote:

> Hi!
> 
> 2023-10-19 at 09:35, Herve Codina wrote:
> > i2c-mux-gpmux uses the pair of_find_i2c_adapter_by_node() /
> > i2c_put_adapter(). These pair alone is not correct to properly lock the
> > I2C parent adapter.
> > 
> > Indeed, i2c_put_adapter() decrements the module refcount while
> > of_find_i2c_adapter_by_node() does not increment it. This leads to an
> > overflow over zero of the parent adapter user counter.  
> 
> Perhaps "... underflow of the parent module refcount."?

Yes, will be changed in the next iteration.

> 
> > 
> > Use the dedicated function, of_get_i2c_adapter_by_node(), to handle
> > correctly the module refcount.
> > 
> > Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>  
> 
> Good find, and sorry about that!
> 
> Fixes: ac8498f0ce53 ("i2c: i2c-mux-gpmux: new driver")
> Acked-by: Peter Rosin <peda@xxxxxxxxxx>

Will be added in the next iteration.

Thanks for the review,
Hervé