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Date:   Thu, 14 Sep 2023 11:02:15 +0100
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     James Morse <james.morse@arm.com>
Cc:     linux-pm@vger.kernel.org, loongarch@lists.linux.dev,
        linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-riscv@lists.infradead.org, kvmarm@lists.linux.dev,
        x86@kernel.org, Salil Mehta <salil.mehta@huawei.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        jianyong.wu@arm.com, justin.he@arm.com
Subject: Re: [RFC PATCH v2 07/35] x86: intel_epb: Don't rely on link order
Message-ID: <ZQLaJ83D3MA1SOAS@shell.armlinux.org.uk>
References: <20230913163823.7880-1-james.morse@arm.com>
 <20230913163823.7880-8-james.morse@arm.com>
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On Wed, Sep 13, 2023 at 04:37:55PM +0000, James Morse wrote:
> intel_epb_init() is called as a subsys_initcall() to register cpuhp
> callbacks. The callbacks make use of get_cpu_device() which will return
> NULL unless register_cpu() has been called. register_cpu() is called
> from topology_init(), which is also a subsys_initcall().
> 
> This is fragile. Moving the register_cpu() to a different
> subsys_initcall()  leads to a NULL derefernce during boot.
> 
> Make intel_epb_init() a late_initcall(), user-space can't provide a
> policy before this point anyway.
> 
> Signed-off-by: James Morse <james.morse@arm.com>

I think someone knowledgeable from x86 land needs to ack/review this.

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