[RFC PATCH v2 05/35] drivers: base: Print a warning instead of panic() when register_cpu() fails

[Russell King (Oracle)]

On Wed, Sep 13, 2023 at 04:37:53PM +0000, James Morse wrote:
> loongarch, mips, parisc, riscv and sh all print a warning if
> register_cpu() returns an error. Architectures that use
> GENERIC_CPU_DEVICES call panic() instead.
> 
> Errors in this path indicate something is wrong with the firmware
> description of the platform, but the kernel is able to keep running.
> 
> Downgrade this to a warning to make it easier to debug this issue.
> 
> This will allow architectures that switching over to GENERIC_CPU_DEVICES
> to drop their warning, but keep the existing behaviour.
> 
> Signed-off-by: James Morse <james.morse at arm.com>

Assuming other architectures do similar to x86 (which only return the
error code from register_cpu()), the only error that would occur here
is if device_register() fails, which would be catastophic, and I
suspect the system would fail to boot anyway.

Downgrading the panic to a warning at least gives us a chance that
the system may come up sufficiently to examine what happened, so I
think this makes sense:

Reviewed-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>

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