linux-kernel - Re: [PATCH v2] greybus/operation: Drop reference when message has been sent

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Message-ID: <YEjWQObSkj6QbXZP@hovoldconsulting.com>
Date:   Wed, 10 Mar 2021 15:22:56 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Cc:     elder@...nel.org, gregkh@...uxfoundation.org,
        greybus-dev@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] greybus/operation: Drop reference when message has
 been sent

On Wed, Mar 10, 2021 at 06:17:36AM -0800, Lv Yunlong wrote:
> In gb_operation_response_send, get an extra reference
> before gb_message_send() with this comment "/* Reference will
> be dropped when message has been sent. */". Therefore, we
> should drop the got reference not only in the error branch,
> but also in the complete branch.
> 
> Signed-off-by: Lv Yunlong <lyl2019@...l.ustc.edu.cn>
> ---
>  drivers/greybus/operation.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/greybus/operation.c b/drivers/greybus/operation.c
> index 8459e9bc0749..500b3fe53a04 100644
> --- a/drivers/greybus/operation.c
> +++ b/drivers/greybus/operation.c
> @@ -855,6 +855,10 @@ static int gb_operation_response_send(struct gb_operation *operation,
>  	if (ret)
>  		goto err_put_active;
>  
> +	/*Drop reference after message send completes. */
> +	gb_operation_put_active(operation);
> +	gb_operation_put(operation);

No, this is broken.

The reference is dropped in greybus_message_sent().

Johan