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: <c9dffece-0d4b-4b36-af04-4b2031d9f037@pf.is.s.u-tokyo.ac.jp>
Date: Thu, 19 Dec 2024 10:37:52 +0900
From: Joe Hattori <joe@...is.s.u-tokyo.ac.jp>
To: Stephen Boyd <sboyd@...nel.org>, mchehab+huawei@...nel.org
Cc: linux-kernel@...r.kernel.org, krzk@...nel.org
Subject: Re: [PATCH v2] spmi: hisi-spmi-controller: manage the OF node
 reference in device initialization and cleanup

Thank you for your review.

On 12/19/24 04:49, Stephen Boyd wrote:
> 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.

Addressed in the v3 patch.

> 
>>
>> 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?

Yes, setting also the fwnode sounds cleaner. Applied in the v3 patch.

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

Best,
Joe