Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.33 as permitted sender) client-ip=23.128.96.33;
Date:   Thu, 14 Sep 2023 10:52:57 +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 05/35] drivers: base: Print a warning instead of
 panic() when register_cpu() fails
Message-ID: <ZQLX+XEe2gD/btaQ@shell.armlinux.org.uk>
References: <20230913163823.7880-1-james.morse@arm.com>
 <20230913163823.7880-6-james.morse@arm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230913163823.7880-6-james.morse@arm.com>
Sender: Russell King (Oracle) <linux@armlinux.org.uk>
Precedence: bulk

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@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@armlinux.org.uk>

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!