linux-kernel - Re: [resend, PATCH v2 1/1] kexec: Remove unused code in kimage_load_cma

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Message-ID: <aNLd_6CO6YMvm2MN@80a9970eed1e>
Date: Tue, 23 Sep 2025 10:50:55 -0700
From: Justinien Bouron <jbouron@...zon.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC: <kexec@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<llvm@...ts.linux.dev>, Andrew Morton <akpm@...ux-foundation.org>, Baoquan He
	<bhe@...hat.com>, Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers
	<nick.desaulniers+lkml@...il.com>, Bill Wendling <morbo@...gle.com>, "Justin
 Stitt" <justinstitt@...gle.com>, Justinien Bouron <jbouron@...zon.com>
Subject: Re: [resend, PATCH v2 1/1] kexec: Remove unused code in
 kimage_load_cma_segment()

On Tue, Sep 16, 2025 at 02:51:09PM +0200, Andy Shevchenko wrote:
> clang is not happy about set but unused variable:
> 
> kernel/kexec_core.c:745:16: error: variable 'maddr' set but not used [-Werror,-Wunused-but-set-variable]
>   745 |         unsigned long maddr;
>       |                       ^
> 1 error generated.
> 
> Fix the compilation breakage (`make W=1` build) by removing unused variable.
> 
> As Nathan noted, GCC 16 produces the similar warning;
> 
> Fixes: f4fecb50d6e1 ("kexec_core: remove superfluous page offset handling in segment loading")
FYI the commit this patch is fixing (i.e. f4fecb50d6e1) is going to need a
second revision as well (I haven't submitted it yet, still working on it), this
means that your "Fixes:" tag will need to be changed again, requiring a 3rd
revision.

I am not sure what is the proper way forward here. Should I:
    - Send my v2, without fixing the unused variable and then you send your v3
      with the updated "Fixes:" tag pointing to my v2.
    - OR fixing the unused variable in my v2 (i.e. "absorb" this patch in my
      v2).
In the latter case, I am not sure how I am supposed to credit the work in this
case? Do I need to add another "Signed-off-by: Andy Shevchenko" besides mine?

I'm still learning the ropes on how to contribute through the mailing list so I
would be grateful if you could share your input on what's the proper way forward
here.

Best,
Justinien
> Reviewed-by: Nathan Chancellor <nathan@...nel.org>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
> 
> v2: fixed Fixes (Nathan), added a note about GCC (Nathan), added tag (Nathan)
> 
>  kernel/kexec_core.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 5357ed39e9d1..32722926bc7e 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -742,7 +742,6 @@ static int kimage_load_cma_segment(struct kimage *image, int idx)
>  	struct kexec_segment *segment = &image->segment[idx];
>  	struct page *cma = image->segment_cma[idx];
>  	char *ptr = page_address(cma);
> -	unsigned long maddr;
>  	size_t ubytes, mbytes;
>  	int result = 0;
>  	unsigned char __user *buf = NULL;
> @@ -754,7 +753,6 @@ static int kimage_load_cma_segment(struct kimage *image, int idx)
>  		buf = segment->buf;
>  	ubytes = segment->bufsz;
>  	mbytes = segment->memsz;
> -	maddr = segment->mem;
>  
>  	/* Then copy from source buffer to the CMA one */
>  	while (mbytes) {
> @@ -782,7 +780,6 @@ static int kimage_load_cma_segment(struct kimage *image, int idx)
>  		}
>  
>  		ptr    += mchunk;
> -		maddr  += mchunk;
>  		mbytes -= mchunk;
>  
>  		cond_resched();
> -- 
> 2.50.1
>