Re: [PATCH v2 6/8] clk: clocking-wizard: Use dev_err_probe() when mapping registers

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:

New issues:
- [Medium] Wrapping `devm_platform_ioremap_resource()` in `dev_err_probe()` causes redundant double error logging, and the commit message's justification regarding deferred-probe behavior is factually incorrect.

Pre-existing issues:
- [High] Registering the exact same `struct notifier_block` instance (`clk_wzrd->nb`) to two different clock notifier chains corrupts the SRCU linked lists.
--

--- Patch [6]: [PATCH v2 6/8] clk: clocking-wizard: Use dev_err_probe() when mapping registers ---
commit 62924401e7cb937dd4102855b2b6f8bf68175467
Author: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>

clk: clocking-wizard: Use dev_err_probe() when mapping registers

This commit updates the error handling for mapping registers in the clock
wizard driver. It replaces a direct return of the error code with a call
to dev_err_probe().

> Align the devm_platform_ioremap_resource() error path with clk_in1 and
> s_axi_aclk handling for consistent logging and deferred-probe behavior.

[Severity: Medium]
Is this description accurate regarding deferred-probe behavior?

Since devm_platform_ioremap_resource() never returns -EPROBE_DEFER, could
the commit message be more precise about what deferred-probe behavior is
expected here?

> diff --git a/drivers/clk/xilinx/clk-xlnx-clock-wizard.c b/drivers/clk/xilinx/clk-xlnx-clock-wizard.c
> index fe73ee02b54ee..381e396aef0e7 100644
> --- a/drivers/clk/xilinx/clk-xlnx-clock-wizard.c
> +++ b/drivers/clk/xilinx/clk-xlnx-clock-wizard.c
> @@ -1277,7 +1277,8 @@ static int clk_wzrd_probe(struct platform_device *pdev)
>  
>  		clk_wzrd->base = devm_platform_ioremap_resource(pdev, 0);
>  		if (IS_ERR(clk_wzrd->base))
> -			return PTR_ERR(clk_wzrd->base);
> +			return dev_err_probe(&pdev->dev, PTR_ERR(clk_wzrd->base),
> +					     "failed to map registers\n");

[Severity: Medium]
Does wrapping devm_platform_ioremap_resource() with dev_err_probe() cause
redundant error logging?

Because devm_platform_ioremap_resource() calls __devm_ioremap_resource()
internally, which natively utilizes dev_err_probe() to print detailed error
messages for all its failure modes, would this exact same failure end up
being logged twice?

[Severity: High]
This is a pre-existing issue, but does registering the same notifier block
instance to two different clock notifier chains corrupt the SRCU linked
lists?

Looking at clk_wzrd_probe(), the driver attempts to register the exact same
notifier block instance to both clk_in1 and axi_clk:

drivers/clk/xilinx/clk-xlnx-clock-wizard.c:clk_wzrd_probe() {
    ...
    clk_wzrd->nb.notifier_call = clk_wzrd_clk_notifier;

    ret = devm_clk_notifier_register(&pdev->dev, clk_wzrd->clk_in1,
                                     &clk_wzrd->nb);
    if (ret)
        dev_warn(&pdev->dev,
                 "unable to register clock notifier\n");

    ret = devm_clk_notifier_register(&pdev->dev, clk_wzrd->axi_clk,
                                     &clk_wzrd->nb);
    ...
}

Because a notifier_block structure contains a next pointer used to link it
into a singly-linked list, does registering it to the second clock's chain
overwrite the next pointer and corrupt the first clock's notifier list?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260709111403.1579159-1-shubhrajyoti.datta@amd.com?part=6