linux-kernel - Re: [PATCH] clk: clkdev: don't fail clkdev

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Date: Tue, 28 May 2024 04:21:59 -0700
From: Ron Economos <re@...z.net>
To: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
 linux-clk@...r.kernel.org
Cc: Stephen Boyd <sboyd@...nel.org>,
 Samuel Holland <samuel.holland@...ive.com>,
 Guenter Roeck <linux@...ck-us.net>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 Dinh Nguyen <dinguyen@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
 Michael Turquette <mturquette@...libre.com>,
 Paul Walmsley <paul.walmsley@...ive.com>, Rob Herring <robh@...nel.org>,
 Yang Li <yang.lee@...ux.alibaba.com>, linux-kernel@...r.kernel.org,
 linux-riscv@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
 regressions@...ts.linux.dev
Subject: Re: [PATCH] clk: clkdev: don't fail clkdev_alloc() if over-sized

On 5/28/24 1:15 AM, Russell King (Oracle) wrote:
> Don't fail clkdev_alloc() if the strings are over-sized. In this case,
> the entry will not match during lookup, so its useless. However, since
> code fails if we return NULL leading to boot failure, return a dummy
> entry with the connection and device IDs set to "bad".
>
> Leave the warning so these problems can be found, and the useless
> wasteful clkdev registrations removed.
>
> Fixes: 8d532528ff6a ("clkdev: report over-sized strings when creating clkdev entries")
> Closes: https://lore.kernel.org/linux-clk/7eda7621-0dde-4153-89e4-172e4c095d01@roeck-us.net.
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> ---
>
> Please try this patch, which should allow the platform to boot, bit will
> intentionally issue lots of warnings. There is a separate patch posted
> recently that removes the useless registration with clkdev.
>
>   drivers/clk/clkdev.c | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
> index 6a77d7e201a9..2f83fb97c6fb 100644
> --- a/drivers/clk/clkdev.c
> +++ b/drivers/clk/clkdev.c
> @@ -204,8 +204,15 @@ vclkdev_alloc(struct clk_hw *hw, const char *con_id, const char *dev_fmt,
>   	pr_err("%pV:%s: %s ID is greater than %zu\n",
>   	       &vaf, con_id, failure, max_size);
>   	va_end(ap_copy);
> -	kfree(cla);
> -	return NULL;
> +
> +	/*
> +	 * Don't fail in this case, but as the entry won't ever match just
> +	 * fill it with something that also won't match.
> +	 */
> +	strscpy(cla->con_id, "bad", sizeof(cla->con_id));
> +	strscpy(cla->dev_id, "bad", sizeof(cla->dev_id));
> +
> +	return &cla->cl;
>   }
>   
>   static struct clk_lookup *

Works good. Here's what it looks like on HiFive Unmatched.

[0.389138] riscv-plic c000000.interrupt-controller: mapped 69 interrupts 
with 4 handlers for 9 contexts.
[0.390710] shpchp: Standard Hot Plug PCI Controller Driver version: 0.4
[0.392743] 10000000.clock-controller:corepll: device ID is greater than 24
[0.392792] 10000000.clock-controller:ddrpll: device ID is greater than 24
[0.392820] 10000000.clock-controller:gemgxlpll: device ID is greater 
than 24
[0.392847] 10000000.clock-controller:dvfscorepll: device ID is greater 
than 24
[0.392876] 10000000.clock-controller:hfpclkpll: device ID is greater 
than 24
[0.392903] 10000000.clock-controller:cltxpll: device ID is greater than 24
[0.392929] 10000000.clock-controller:tlclk: device ID is greater than 24
[0.392955] 10000000.clock-controller:pclk: device ID is greater than 24
[0.392981] 10000000.clock-controller:pcie_aux: device ID is greater than 24
[0.394620] Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled
[0.413222] SuperH (H)SCI(F) driver initialized

Tested-by: Ron Economos <re@...z.net>