linux-kernel - Re: [PATCH] xen: remove incorrect forward declaration

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Message-ID: <57333C1D.8070405@suse.com>
Date:	Wed, 11 May 2016 16:05:17 +0200
From:	Juergen Gross <jgross@...e.com>
To:	Arnd Bergmann <arnd@...db.de>,
	David Vrabel <david.vrabel@...rix.com>
Cc:	Ross Lagerwall <ross.lagerwall@...rix.com>, stable@...r.kernel.org,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	Daniel Kiper <daniel.kiper@...cle.com>,
	Julien Grall <julien.grall@...rix.com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Vitaly Kuznetsov <vkuznets@...hat.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xen: remove incorrect forward declaration

On 11/05/16 15:07, Arnd Bergmann wrote:
> A bugfix patch for the xen balloon driver introduced a forward
> declaration for a static function that is conditionally compiled,
> causing a warning if only the declaration but not the definition
> are there:
> 
> drivers/xen/balloon.c:154:13: error: 'release_memory_resource' declared 'static' but never defined [-Werror=unused-function]
>  static void release_memory_resource(struct resource *resource);
> 
> This removes the declaration again and instead moves the function
> definition to the right place, before its first caller and inside
> of the #ifdef protecting both.
> 
> The patch that introduced the warning is marked for stable
> backports, so if that gets applied to 4.4, so should this one.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> Fixes: dfd74a1edfab ("xen/balloon: Fix crash when ballooning on x86 32 bit PAE")
> Cc: stable@...r.kernel.org

So you've CC'ed Ross, who sent the very same patch just yesterday, but
without the backport request.

Confused,

Juergen

> ---
>  drivers/xen/balloon.c | 28 +++++++++++++---------------
>  1 file changed, 13 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index d46839f51e73..e4db19e88ab1 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -151,8 +151,6 @@ static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
>  static void balloon_process(struct work_struct *work);
>  static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
>  
> -static void release_memory_resource(struct resource *resource);
> -
>  /* When ballooning out (allocating memory to return to Xen) we don't really
>     want the kernel to try too hard since that can trigger the oom killer. */
>  #define GFP_BALLOON \
> @@ -248,6 +246,19 @@ static enum bp_state update_schedule(enum bp_state state)
>  }
>  
>  #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
> +static void release_memory_resource(struct resource *resource)
> +{
> +	if (!resource)
> +		return;
> +
> +	/*
> +	 * No need to reset region to identity mapped since we now
> +	 * know that no I/O can be in this region
> +	 */
> +	release_resource(resource);
> +	kfree(resource);
> +}
> +
>  static struct resource *additional_memory_resource(phys_addr_t size)
>  {
>  	struct resource *res;
> @@ -286,19 +297,6 @@ static struct resource *additional_memory_resource(phys_addr_t size)
>  	return res;
>  }
>  
> -static void release_memory_resource(struct resource *resource)
> -{
> -	if (!resource)
> -		return;
> -
> -	/*
> -	 * No need to reset region to identity mapped since we now
> -	 * know that no I/O can be in this region
> -	 */
> -	release_resource(resource);
> -	kfree(resource);
> -}
> -
>  static enum bp_state reserve_additional_memory(void)
>  {
>  	long credit;
>