linux-kernel - Re: [PATCH] docs: kref: Clarify the use of two kref

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Message-ID: <20200219035818.08ad246f@lwn.net>
Date:   Wed, 19 Feb 2020 03:58:18 -0700
From:   Jonathan Corbet <corbet@....net>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] docs: kref: Clarify the use of two kref_put() in
 example code

On Thu, 13 Feb 2020 18:23:11 +0530
Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org> wrote:

> Eventhough the current documentation explains that the reference count
> gets incremented by both kref_init() and kref_get(), it is often
> misunderstood that only one instance of kref_put() is needed in the
> example code. So let's clarify that a bit.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  Documentation/kref.txt | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/kref.txt b/Documentation/kref.txt
> index 3af384156d7e..c61eea6f1bf2 100644
> --- a/Documentation/kref.txt
> +++ b/Documentation/kref.txt
> @@ -128,6 +128,10 @@ since we already have a valid pointer that we own a refcount for.  The
>  put needs no lock because nothing tries to get the data without
>  already holding a pointer.
>  
> +In the above example, kref_put() will be called 2 times in both success
> +and error paths. This is necessary because the reference count got
> +incremented 2 times by kref_init() and kref_get().

Out of curiosity, where have you seen this misunderstanding happening?
I'm not really opposed to this change, but I don't understand why it's
really needed.

Thanks,

jon