Re: [PATCH] clocksource: hyper-v: unexport __init-annotated hv_init_clocksource()

[Wei Liu]

On Mon, Jun 06, 2022 at 02:02:38PM +0900, Masahiro Yamada wrote:
> EXPORT_SYMBOL and __init is a bad combination because the .init.text
> section is freed up after the initialization. Hence, modules cannot
> use symbols annotated __init. The access to a freed symbol may end up
> with kernel panic.
> 
> modpost used to detect it, but it has been broken for a decade.
> 
> Recently, I fixed modpost so it started to warn it again, then this
> showed up in linux-next builds.
> 
> There are two ways to fix it:
> 
>   - Remove __init
>   - Remove EXPORT_SYMBOL
> 
> I chose the latter for this case because the only in-tree call-site,
> arch/x86/kernel/cpu/mshyperv.c is never compiled as modular.
> (CONFIG_HYPERVISOR_GUEST is boolean)
> 
> Fixes: dd2cb348613b ("clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic")
> Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>

Applied to hyperv-fixes. Thanks.