linux-kernel - Re: [PATCH bpf-next 1/9] firmware/psci: fix missing '%u' format literal in kthread_create_on

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Message-Id: <302ead12-9bb1-4c22-adf5-c89c2e6d059e@app.fastmail.com>
Date: Fri, 30 Aug 2024 16:31:08 -0700
From: "Daniel Xu" <dxu@...uu.xyz>
To: "Alexander Lobakin" <aleksander.lobakin@...el.com>,
 "Alexei Starovoitov" <ast@...nel.org>,
 "Daniel Borkmann" <daniel@...earbox.net>,
 "Andrii Nakryiko" <andrii@...nel.org>
Cc: "Lorenzo Bianconi" <lorenzo@...nel.org>,
 "John Fastabend" <john.fastabend@...il.com>,
 "Jesper Dangaard Brouer" <hawk@...nel.org>,
 "Martin KaFai Lau" <martin.lau@...ux.dev>,
 "David Miller" <davem@...emloft.net>, "Eric Dumazet" <edumazet@...gle.com>,
 "Jakub Kicinski" <kuba@...nel.org>, "Paolo Abeni" <pabeni@...hat.com>,
 "bpf@...r.kernel.org" <bpf@...r.kernel.org>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next 1/9] firmware/psci: fix missing '%u' format literal in
 kthread_create_on_cpu()

On Fri, Aug 30, 2024, at 9:25 AM, Alexander Lobakin wrote:
> kthread_create_on_cpu() always requires format string to contain one
> '%u' at the end, as it automatically adds the CPU ID when passing it
> to kthread_create_on_node(). The former doesn't marked as __printf()
> as it's not printf-like itself, which effectively hides this from
> the compiler.
> If you convert this function to printf-like, you'll see the following:
>
> In file included from drivers/firmware/psci/psci_checker.c:15:
> drivers/firmware/psci/psci_checker.c: In function 'suspend_tests':
> drivers/firmware/psci/psci_checker.c:401:48: warning: too many 
> arguments for format [-Wformat-extra-args]
>      401 |                                                
> "psci_suspend_test");
>          |                                                
> ^~~~~~~~~~~~~~~~~~~
> drivers/firmware/psci/psci_checker.c:400:32: warning: data argument not 
> used by format string [-Wformat-extra-args]
>      400 |                                                (void 
> *)(long)cpu, cpu,
>          |                                                              
>      ^
>      401 |                                                
> "psci_suspend_test");
>          |                                                
> ~~~~~~~~~~~~~~~~~~~
>
> Add the missing format literal to fix this. Now the corresponding
> kthread will be named as "psci_suspend_test-<cpuid>", as it's meant by
> kthread_create_on_cpu().
>
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: 
> https://lore.kernel.org/oe-kbuild-all/202408141012.KhvKaxoh-lkp@intel.com
> Closes: 
> https://lore.kernel.org/oe-kbuild-all/202408141243.eQiEOQQe-lkp@intel.com
> Fixes: ea8b1c4a6019 ("drivers: psci: PSCI checker module")
> Cc: stable@...r.kernel.org # 4.10+
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@...el.com>
> ---
>  drivers/firmware/psci/psci_checker.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/psci/psci_checker.c 
> b/drivers/firmware/psci/psci_checker.c
> index 116eb465cdb4..ecc511c745ce 100644
> --- a/drivers/firmware/psci/psci_checker.c
> +++ b/drivers/firmware/psci/psci_checker.c
> @@ -398,7 +398,7 @@ static int suspend_tests(void)
> 
>  		thread = kthread_create_on_cpu(suspend_test_thread,
>  					       (void *)(long)cpu, cpu,
> -					       "psci_suspend_test");
> +					       "psci_suspend_test-%u");
>  		if (IS_ERR(thread))
>  			pr_err("Failed to create kthread on CPU %d\n", cpu);
>  		else
> -- 
> 2.46.0

Acked-by: Daniel Xu <dxu@...uu.xyz>