linux-kernel - Re: [PATCH] arch: x86: kernel: Add missing of_node

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Date:   Wed, 15 Jun 2022 10:26:16 -0600
From:   Rob Herring <robh@...nel.org>
To:     Liang He <windhl@....com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Frank Rowand <frank.rowand@...y.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arch: x86: kernel: Add missing of_node_put() in devicetree.c

On Wed, Jun 15, 2022 at 9:03 AM Liang He <windhl@....com> wrote:
>
> In dtb_setup_hpet(), of_find_compatible_node() will return a node
> pointer with refcount incremented. We should use of_node_put() when it
> is not used anymore.
>
> Signed-off-by: Liang He <windhl@....com>
> ---
>  arch/x86/kernel/devicetree.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
> index 5cd51f25f446..6a386424ddf7 100644
> --- a/arch/x86/kernel/devicetree.c
> +++ b/arch/x86/kernel/devicetree.c
> @@ -120,6 +120,9 @@ static void __init dtb_setup_hpet(void)
>         if (!dn)
>                 return;
>         ret = of_address_to_resource(dn, 0, &r);
> +
> +       of_node_put(dn);
> +

You don't want a put on success. If you are using the device, then you
want to hold a reference to it.

I would guess that if you have an error here and don't have your
timer, you're not going to finish booting anyways.

Finally, wouldn't dtb_lapic_setup() and dtb_add_ioapic() also need a
similar change? But again, if those aren't initialized, you probably
aren't getting very far.


>         if (ret) {
>                 WARN_ON(1);
>                 return;
> --
> 2.25.1
>