linux-kernel - Re: [PATCH v2 06/11] driver core: fw_devlink: Allow marking a fwnode link as being part of a cycle

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Message-ID: <Y9OaaC806Ywg7rM9@smile.fi.intel.com>
Date:   Fri, 27 Jan 2023 11:33:28 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Cristian Marussi <cristian.marussi@....com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Magnus Damm <magnus.damm@...il.com>,
        Len Brown <lenb@...nel.org>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Tony Lindgren <tony@...mide.com>,
        Linux Kernel Functional Testing <lkft@...aro.org>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        Abel Vesa <abel.vesa@...aro.org>,
        Alexander Stein <alexander.stein@...tq-group.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        John Stultz <jstultz@...gle.com>,
        Doug Anderson <dianders@...omium.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Maxim Kiselev <bigunclemax@...il.com>,
        Maxim Kochetkov <fido_max@...ox.ru>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Luca Weiss <luca.weiss@...rphone.com>,
        Colin Foster <colin.foster@...advantage.com>,
        Martin Kepplinger <martin.kepplinger@...i.sm>,
        Jean-Philippe Brucker <jpb@...nel.org>,
        kernel-team@...roid.com, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-gpio@...r.kernel.org,
        devicetree@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-acpi@...r.kernel.org
Subject: Re: [PATCH v2 06/11] driver core: fw_devlink: Allow marking a fwnode
 link as being part of a cycle

On Thu, Jan 26, 2023 at 04:11:33PM -0800, Saravana Kannan wrote:
> To improve detection and handling of dependency cycles, we need to be
> able to mark fwnode links as being part of cycles. fwnode links marked
> as being part of a cycle should not block their consumers from probing.

...

> +	list_for_each_entry(link, &fwnode->suppliers, c_hook) {
> +		if (link->flags & FWLINK_FLAG_CYCLE)
> +			continue;
> +		return link->supplier;

Hmm...

		if (!(link->flags & FWLINK_FLAG_CYCLE))
			return link->supplier;

?

> +	}
> +
> +	return NULL;

...

> -	if (dev->fwnode && !list_empty(&dev->fwnode->suppliers) &&
> -	    !fw_devlink_is_permissive()) {
> -		sup_fw = list_first_entry(&dev->fwnode->suppliers,
> -					  struct fwnode_link,
> -					  c_hook)->supplier;
> +	sup_fw = fwnode_links_check_suppliers(dev->fwnode);

dev_fwnode() ?

...

> -	val = !list_empty(&dev->fwnode->suppliers);
> +	mutex_lock(&fwnode_link_lock);
> +	val = !!fwnode_links_check_suppliers(dev->fwnode);

Ditto?

> +	mutex_unlock(&fwnode_link_lock);

-- 
With Best Regards,
Andy Shevchenko