Messages in this thread | | | Date | Thu, 19 Oct 2023 11:26:41 +0200 | Subject | Re: [PATCH 3/3] i2c: muxes: i2c-mux-gpmux: Use of_get_i2c_adapter_by_node() | From | Peter Rosin <> |
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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."?
> > Use the dedicated function, of_get_i2c_adapter_by_node(), to handle > correctly the module refcount. > > Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Good find, and sorry about that!
Fixes: ac8498f0ce53 ("i2c: i2c-mux-gpmux: new driver") Acked-by: Peter Rosin <peda@axentia.se>
Cheers, Peter
> --- > drivers/i2c/muxes/i2c-mux-gpmux.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/i2c/muxes/i2c-mux-gpmux.c b/drivers/i2c/muxes/i2c-mux-gpmux.c > index baccf4bfaf02..8305661e1253 100644 > --- a/drivers/i2c/muxes/i2c-mux-gpmux.c > +++ b/drivers/i2c/muxes/i2c-mux-gpmux.c > @@ -52,7 +52,7 @@ static struct i2c_adapter *mux_parent_adapter(struct device *dev) > dev_err(dev, "Cannot parse i2c-parent\n"); > return ERR_PTR(-ENODEV); > } > - parent = of_find_i2c_adapter_by_node(parent_np); > + parent = of_get_i2c_adapter_by_node(parent_np); > of_node_put(parent_np); > if (!parent) > return ERR_PTR(-EPROBE_DEFER);
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