netdev - Re: [PATCH V2 net-next] net: wwan: t7xx: Add port for modem logging

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Date:   Sun, 2 Oct 2022 15:38:47 +0200
From:   Loic Poulain <loic.poulain@...aro.org>
To:     m.chetan.kumar@...ux.intel.com
Cc:     netdev@...r.kernel.org, kuba@...nel.org, davem@...emloft.net,
        johannes@...solutions.net, ryazanov.s.a@...il.com,
        krishna.c.sudi@...el.com, linuxwwan@...el.com,
        Moises Veleta <moises.veleta@...ux.intel.com>,
        Devegowda Chandrashekar <chandrashekar.devegowda@...el.com>,
        Ricardo Martinez <ricardo.martinez@...ux.intel.com>
Subject: Re: [PATCH V2 net-next] net: wwan: t7xx: Add port for modem logging

On Fri, 30 Sept 2022 at 15:55, <m.chetan.kumar@...ux.intel.com> wrote:
>
> From: Moises Veleta <moises.veleta@...ux.intel.com>
>
> The Modem Logging (MDL) port provides an interface to collect modem
> logs for debugging purposes. MDL is supported by the relay interface,
> and the mtk_t7xx port infrastructure. MDL allows user-space apps to
> control logging via mbim command and to collect logs via the relay
> interface, while port infrastructure facilitates communication between
> the driver and the modem.
>
> Signed-off-by: Moises Veleta <moises.veleta@...ux.intel.com>
> Signed-off-by: M Chetan Kumar <m.chetan.kumar@...ux.intel.com>
> Signed-off-by: Devegowda Chandrashekar <chandrashekar.devegowda@...el.com>
> Acked-by: Ricardo Martinez <ricardo.martinez@...ux.intel.com>
> --
> v2
>  * Removed debugfs control port.
>  * Initialize in Notify function upon handshake completion.
>  * Remove trace write function, MBIM will send commands.
> ---
>  drivers/net/wwan/Kconfig                |   1 +
>  drivers/net/wwan/t7xx/Makefile          |   3 +
>  drivers/net/wwan/t7xx/t7xx_hif_cldma.c  |   2 +
>  drivers/net/wwan/t7xx/t7xx_port.h       |   5 ++
>  drivers/net/wwan/t7xx/t7xx_port_proxy.c |  12 +++
>  drivers/net/wwan/t7xx/t7xx_port_proxy.h |   4 +
>  drivers/net/wwan/t7xx/t7xx_port_trace.c | 112 ++++++++++++++++++++++++
>  7 files changed, 139 insertions(+)
>  create mode 100644 drivers/net/wwan/t7xx/t7xx_port_trace.c
>

[...]

> +
> +static void t7xx_port_trace_md_state_notify(struct t7xx_port *port, unsigned int state)
> +{
> +       struct rchan *relaych;
> +
> +       if (state != MD_STATE_READY || port->relaych)
> +               return;
> +
> +       port->debugfs_wwan_dir = wwan_get_debugfs_dir(port->dev);
> +       if (IS_ERR(port->debugfs_wwan_dir))
> +               port->debugfs_wwan_dir = NULL;

Why continuing here despite the error? Is it a possible valid scenario?

> +
> +       port->debugfs_dir = debugfs_create_dir(KBUILD_MODNAME, port->debugfs_wwan_dir);
> +       if (IS_ERR_OR_NULL(port->debugfs_dir)) {
> +               wwan_put_debugfs_dir(port->debugfs_wwan_dir);

port->debugfs_wwan_dir can be NULL here...

> +               dev_err(port->dev, "Unable to create debugfs for trace");
> +               return;
> +       }
> +
> +       relaych = relay_open("relay_ch", port->debugfs_dir, T7XX_TRC_SUB_BUFF_SIZE,
> +                            T7XX_TRC_N_SUB_BUFF, &relay_callbacks, NULL);
> +       if (!relaych)
> +               goto err_rm_debugfs_dir;
> +
> +       port->relaych = relaych;
> +       return;
> +
> +err_rm_debugfs_dir:
> +       debugfs_remove_recursive(port->debugfs_dir);
> +       wwan_put_debugfs_dir(port->debugfs_wwan_dir);

same here.

> +       dev_err(port->dev, "Unable to create trace port %s", port->port_conf->name);
> +}
> +
> +struct port_ops t7xx_trace_port_ops = {
> +       .recv_skb = t7xx_trace_port_recv_skb,
> +       .uninit = t7xx_trace_port_uninit,
> +       .md_state_notify = t7xx_port_trace_md_state_notify,
> +};
> --
> 2.34.1
>