Date:   Thu, 26 Jan 2023 16:11:29 -0800
In-Reply-To: <20230127001141.407071-1-saravanak@google.com>
Message-Id: <20230127001141.407071-3-saravanak@google.com>
Mime-Version: 1.0
References: <20230127001141.407071-1-saravanak@google.com>
Subject: [PATCH v2 02/11] driver core: fw_devlink: Improve check for fwnode
 with no device/driver
From:   Saravana Kannan <saravanak@google.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Cristian Marussi <cristian.marussi@arm.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <brgl@bgdev.pl>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>, Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Magnus Damm <magnus.damm@gmail.com>,
        Len Brown <lenb@kernel.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Daniel Scally <djrscally@gmail.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Saravana Kannan <saravanak@google.com>
Cc:     Tony Lindgren <tony@atomide.com>,
        Linux Kernel Functional Testing <lkft@linaro.org>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Abel Vesa <abel.vesa@linaro.org>,
        Alexander Stein <alexander.stein@ew.tq-group.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        John Stultz <jstultz@google.com>,
        Doug Anderson <dianders@chromium.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        Maxim Kiselev <bigunclemax@gmail.com>,
        Maxim Kochetkov <fido_max@inbox.ru>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Luca Weiss <luca.weiss@fairphone.com>,
        Colin Foster <colin.foster@in-advantage.com>,
        Martin Kepplinger <martin.kepplinger@puri.sm>,
        Jean-Philippe Brucker <jpb@kernel.org>,
        kernel-team@android.com, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org,
        devicetree@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
        linux-acpi@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

fw_devlink shouldn't defer the probe of a device to wait on a supplier
that'll never have a struct device or will never be probed by a driver.
We currently check if a supplier falls into this category, but don't
check its ancestors. We need to check the ancestors too because if the
ancestor will never probe, then the supplier will never probe either.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/base/core.c | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index b6d98cc82f26..919728e784e8 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1867,6 +1867,35 @@ static int fw_devlink_relax_cycle(struct device *con, void *sup)
 	return ret;
 }
 
+static bool fwnode_init_without_drv(struct fwnode_handle *fwnode)
+{
+	struct device *dev;
+	bool ret;
+
+	if (!(fwnode->flags & FWNODE_FLAG_INITIALIZED))
+		return false;
+
+	dev = get_dev_from_fwnode(fwnode);
+	ret = !dev || dev->links.status == DL_DEV_NO_DRIVER;
+	put_device(dev);
+
+	return ret;
+}
+
+static bool fwnode_ancestor_init_without_drv(struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *parent;
+
+	fwnode_for_each_parent_node(fwnode, parent) {
+		if (fwnode_init_without_drv(parent)) {
+			fwnode_handle_put(parent);
+			return true;
+		}
+	}
+
+	return false;
+}
+
 /**
  * fw_devlink_create_devlink - Create a device link from a consumer to fwnode
  * @con: consumer device for the device link
@@ -1948,9 +1977,16 @@ static int fw_devlink_create_devlink(struct device *con,
 		goto out;
 	}
 
-	/* Supplier that's already initialized without a struct device. */
-	if (sup_handle->flags & FWNODE_FLAG_INITIALIZED)
+	/*
+	 * Supplier or supplier's ancestor already initialized without a struct
+	 * device or being probed by a driver.
+	 */
+	if (fwnode_init_without_drv(sup_handle) ||
+	    fwnode_ancestor_init_without_drv(sup_handle)) {
+		dev_dbg(con, "Not linking %pfwP - Might never probe\n",
+			sup_handle);
 		return -EINVAL;
+	}
 
 	/*
 	 * DL_FLAG_SYNC_STATE_ONLY doesn't block probing and supports
-- 
2.39.1.456.gfc5497dd1b-goog