linux-kernel - Re: [RFC PATCH v2 07/35] x86: intel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4f368470-83c1-4140-9d0f-e64db3402865@redhat.com>
Date:   Mon, 18 Sep 2023 13:48:47 +1000
From:   Gavin Shan <gshan@...hat.com>
To:     James Morse <james.morse@....com>, linux-pm@...r.kernel.org,
        loongarch@...ts.linux.dev, linux-acpi@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, kvmarm@...ts.linux.dev
Cc:     x86@...nel.org, Salil Mehta <salil.mehta@...wei.com>,
        Russell King <linux@...linux.org.uk>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        jianyong.wu@....com, justin.he@....com
Subject: Re: [RFC PATCH v2 07/35] x86: intel_epb: Don't rely on link order



On 9/14/23 02:37, 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.
                                      ^^^^^^^^^^
                                      s/derefernce/dereference

Reported by ./scripts/checkpatch.pl --codespell

> 
> 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@....com>
> ---
> subsys_initcall_sync() would be an option, but moving the register_cpu()
> calls into ACPI also means adding a safety net for CPUs that are online
> but not described properly by firmware. This lives in subsys_initcall_sync().
> ---
>   arch/x86/kernel/cpu/intel_epb.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/intel_epb.c b/arch/x86/kernel/cpu/intel_epb.c
> index e4c3ba91321c..f18d35fe27a9 100644
> --- a/arch/x86/kernel/cpu/intel_epb.c
> +++ b/arch/x86/kernel/cpu/intel_epb.c
> @@ -237,4 +237,4 @@ static __init int intel_epb_init(void)
>   	cpuhp_remove_state(CPUHP_AP_X86_INTEL_EPB_ONLINE);
>   	return ret;
>   }
> -subsys_initcall(intel_epb_init);
> +late_initcall(intel_epb_init);

Thanks,
Gavin