Date:   Thu, 2 Dec 2021 19:58:14 -0600
From:   Bjorn Andersson <bjorn.andersson@linaro.org>
To:     Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Cc:     Ohad Ben-Cohen <ohad@wizery.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com, julien.massot@iot.bzh
Subject: Re: [PATCH v7 12/12] rpmsg: core: send a ns announcement when a
 default endpoint is created
Message-ID: <Yal5tplvcqDjEeTs@builder.lan>
References: <20211108141937.13016-1-arnaud.pouliquen@foss.st.com>
 <20211108141937.13016-13-arnaud.pouliquen@foss.st.com>
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On Mon 08 Nov 08:19 CST 2021, Arnaud Pouliquen wrote:

> When a channel is created by user space application with the
> RPMSG_CREATE_DEV_IOCTL controls, a ns announcement has to be sent
> (depending on backend) to inform the remote side that a new service
> is available.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> ---
>  drivers/rpmsg/rpmsg_core.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index bdcde57c22f6..63227279397d 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -145,6 +145,9 @@ EXPORT_SYMBOL(rpmsg_destroy_ept);
>   *
>   * This function returns a pointer to an endpoint created and assigned as the default
>   * endpoint of the rpmsg device.
> + * If we need to, we also announce about this channel to the remote
> + * processor. This announcement is needed in case the driver is exposing an rpmsg service that has
> + * been created locally.
>   *
>   * Drivers should provide their @rpdev channel (so the new endpoint would belong
>   * to the same remote processor their channel belongs to), an rx callback
> @@ -161,6 +164,7 @@ struct rpmsg_endpoint *rpmsg_create_default_ept(struct rpmsg_device *rpdev,
>  						struct rpmsg_channel_info chinfo)
>  {
>  	struct rpmsg_endpoint *ept;
> +	int err = 0;
>  
>  	if (WARN_ON(!rpdev))
>  		return NULL;
> @@ -183,6 +187,16 @@ struct rpmsg_endpoint *rpmsg_create_default_ept(struct rpmsg_device *rpdev,
>  	rpdev->ept = ept;
>  	rpdev->src = ept->addr;
>  
> +	if (rpdev->ops->announce_create)
> +		err = rpdev->ops->announce_create(rpdev);
> +	if (err) {
> +		rpmsg_destroy_ept(ept);
> +		rpdev->ept = NULL;
> +		rpdev->src = RPMSG_ADDR_ANY;
> +
> +		return NULL;
> +	}
> +

Unless I'm missing something I think this would be cleaner as:

	if (rpdev->ops->announce_create) {
		err = rpdev->ops->announce_create(rpdev);
		if (err) {
			...;
		}
	}

which also implies that you don't need to zero-initialize err.

Other than that, this looks good and follows what would happen in
rpmsg_dev_probe()...


PS. In rpmsg_dev_probe(), if rpdrv->probe() succeeds but announce_create
returns a failure we will exit the function with an error, which will
just fail really_probe() and we won't ever clean up the device (i.e.
call rpdev->remove()).

Regards,
Bjorn

>  	return ept;
>  }
>  EXPORT_SYMBOL(rpmsg_create_default_ept);
> -- 
> 2.17.1
>