linux-kernel - Re: [PATCH] base: core: Remove WARN

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Date:   Thu, 12 Jul 2018 10:55:01 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     broonie@...nel.org, p.paillet@...com, linux-kernel@...r.kernel.org,
        m.szyprowski@...sung.com,
        Benjamin Gaignard <benjamin.gaignard@...com>
Subject: Re: [PATCH] base: core: Remove WARN_ON from link dependencies check

On Thu, Jul 12, 2018 at 10:06:23AM +0200, Benjamin Gaignard wrote:
> In some cases the link between between customer and supplier
> already exist. Do not warn about already existing dependencies
> because device_link_add() take care of this case.

Why would a link already exist that is asked to be created again?  What
code path causes this?

> 
> Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
> ---
>  drivers/base/core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index df3e1a44707a..fcdc17f0f349 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -105,7 +105,7 @@ static int device_is_dependent(struct device *dev, void *target)
>  	struct device_link *link;
>  	int ret;
>  
> -	if (WARN_ON(dev == target))
> +	if (dev == target)
>  		return 1;
>  
>  	ret = device_for_each_child(dev, target, device_is_dependent);
> @@ -113,7 +113,7 @@ static int device_is_dependent(struct device *dev, void *target)
>  		return ret;
>  
>  	list_for_each_entry(link, &dev->links.consumers, s_node) {
> -		if (WARN_ON(link->consumer == target))
> +		if (link->consumer == target)
>  			return 1;

Both of these WARN_ON are for valid code?  That feels really odd to me,
I need more explanation here please.

thanks,

greg k-h