linux-kernel - Re: [RFC PATCH v4 1/1] serial: core: Start managing serial controllers to enable runtime PM

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Message-ID: <3c87186b-336f-6884-a2c-6ee3c9d70@linux.intel.com>
Date:   Thu, 8 Dec 2022 12:48:47 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Tony Lindgren <tony@...mide.com>
cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@...el.com>,
        Jiri Slaby <jirislaby@...nel.org>,
        Johan Hovold <johan@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-serial <linux-serial@...r.kernel.org>,
        linux-omap@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v4 1/1] serial: core: Start managing serial controllers
 to enable runtime PM

On Thu, 8 Dec 2022, Tony Lindgren wrote:

> * Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com> [221208 09:12]:
> > On Wed, 7 Dec 2022, Tony Lindgren wrote:
> > > +	ret = serial_core_add_one_port(drv, port);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	mutex_lock(&port_mutex);
> > > +
> > > +	/* Inititalize a serial core controller device if needed */
> > > +	ctrl_dev = serial_core_ctrl_find(drv, port->dev, port->ctrl_id);
> > > +	if (!ctrl_dev) {
> > > +		ctrl_dev = serial_core_ctrl_device_add(port);
> > > +		if (!ctrl_dev)
> > > +			goto err_remove_port;
> > > +		allocated = true;
> > > +	}
> > > +
> > > +	/* Initialize a serial core port device */
> > > +	ret = serial_core_port_device_add(ctrl_dev, port);
> > 
> > How is ->port_dev supposed to work here?
> > 
> > ->port_dev is not set until in serial_core_port_device_add() but you made
> > serial_core_add_one_port() call before that.
> 
> Hmm do you mean you want to call serial_core_add_one_port() later after
> serial_core_port_device_add()?
> 
> Or are you seeing some uninitialized use of port->port_dev (and not
> port->dev)?

With the other patch on top of this, yes, I did see uninitialized 
port->port_dev already in serial_core_add_one_port()->uart_configure_port().
While that could be solved by removing the pm_runtime_*() calls from 
there, I think it's a generic problem because after 
serial_core_add_one_port() the port can have anything happening on it, no?


-- 
 i.