linux-kernel - Re: [PATCH v2] spmi: hisi-spmi-controller: manage the OF node reference in device initialization and cleanup

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Message-ID: <beb398abfe3082c128b0393f168dcc86.sboyd@kernel.org>
Date: Wed, 18 Dec 2024 11:49:32 -0800
From: Stephen Boyd <sboyd@...nel.org>
To: Joe Hattori <joe@...is.s.u-tokyo.ac.jp>, mchehab+huawei@...nel.org
Cc: linux-kernel@...r.kernel.org, krzk@...nel.org, Joe Hattori <joe@...is.s.u-tokyo.ac.jp>
Subject: Re: [PATCH v2] spmi: hisi-spmi-controller: manage the OF node reference in device initialization and cleanup

Quoting Joe Hattori (2024-12-17 19:39:54)
> spmi_controller_probe() increments the refcount of an OF node, but does
> not release it. Instead, call of_node_get() in spmi_controller_alloc()
> and release it in spmi_ctrl_release() to avoid the reference leak. Also
> remove the lines in spmi_pmic_arb_bus_init() and spmi_controller_probe()
> where a pdev's of_node is stored after spmi_controller_alloc() is
> called.

That last sentence says what is done but doesn't explain why. Please
explain why stashing the of_node in the two drivers are removed.

> 
> This bug was found by an experimental static analysis tool that I am
> developing.
> 
> Fixes: e562cf3aea3e ("spmi: hisi-spmi-controller: move driver from staging")
> Signed-off-by: Joe Hattori <joe@...is.s.u-tokyo.ac.jp>
[...]
> diff --git a/drivers/spmi/spmi.c b/drivers/spmi/spmi.c
> index fb0101da1485..e662a7a78df2 100644
> --- a/drivers/spmi/spmi.c
> +++ b/drivers/spmi/spmi.c
> @@ -36,6 +36,7 @@ static void spmi_ctrl_release(struct device *dev)
>         struct spmi_controller *ctrl = to_spmi_controller(dev);
>  
>         ida_free(&ctrl_ida, ctrl->nr);
> +       of_node_put(dev->of_node);
>         kfree(ctrl);
>  }
>  
> @@ -458,7 +459,7 @@ struct spmi_controller *spmi_controller_alloc(struct device *parent,
>         ctrl->dev.type = &spmi_ctrl_type;
>         ctrl->dev.bus = &spmi_bus_type;
>         ctrl->dev.parent = parent;
> -       ctrl->dev.of_node = parent->of_node;
> +       ctrl->dev.of_node = of_node_get(parent->of_node);

Do we need to use device_set_node() here?

>         spmi_controller_set_drvdata(ctrl, &ctrl[1]);
>