| Message ID | 20231019073533.386563-4-herve.codina@bootlin.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Fix i2c mux module refcount issues | expand |
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);
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);
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. 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> --- drivers/i2c/muxes/i2c-mux-gpmux.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)