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Message-ID: <20231020083449.3393191f@jic23-huawei>
Date: Fri, 20 Oct 2023 08:34:49 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Herve Codina <herve.codina@...tlin.com>
Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>,
Peter Rosin <peda@...ntia.se>,
Stephen Warren <swarren@...dia.com>,
Rob Herring <robh@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Wolfram Sang <wsa@...nel.org>, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org,
Allan Nielsen <allan.nielsen@...rochip.com>,
Horatiu Vultur <horatiu.vultur@...rochip.com>,
Steen Hegelund <steen.hegelund@...rochip.com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v2 1/3] i2c: muxes: i2c-mux-pinctrl: Use
of_get_i2c_adapter_by_node()
On Thu, 19 Oct 2023 12:10:14 +0200
Herve Codina <herve.codina@...tlin.com> wrote:
> i2c-mux-pinctrl 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
> underflow of the parent module refcount.
>
> Use the dedicated function, of_get_i2c_adapter_by_node(), to handle
> correctly the module refcount.
>
> Fixes: c4aee3e1b0de ("i2c: mux: pinctrl: remove platform_data")
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> Acked-by: Peter Rosin <peda@...ntia.se>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> ---
> drivers/i2c/muxes/i2c-mux-pinctrl.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/muxes/i2c-mux-pinctrl.c b/drivers/i2c/muxes/i2c-mux-pinctrl.c
> index 18236b9fa14a..6ebca7bfd8a2 100644
> --- a/drivers/i2c/muxes/i2c-mux-pinctrl.c
> +++ b/drivers/i2c/muxes/i2c-mux-pinctrl.c
> @@ -62,7 +62,7 @@ static struct i2c_adapter *i2c_mux_pinctrl_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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