linux-kernel - [PATCH v2] driver core: Print device when resources present in really

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Message-Id: <20191206132219.28908-1-geert+renesas@glider.be>
Date:   Fri,  6 Dec 2019 14:22:19 +0100
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH v2] driver core: Print device when resources present in really_probe()

If a device already has devres items attached before probing, a warning
backtrace is printed.  However, this backtrace does not reveal the
offending device, leaving the user uninformed.  Furthermore, using
WARN_ON() causes systems with panic-on-warn to reboot.

Fix this by replacing the WARN_ON() by a dev_crit() message.
Abort probing the device, to prevent doing more damage to the device's
resources.

Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
v2:
  - Use dev_crit() instead of dev_WARN_ON(),
  - Abort probing, as this is a critical situation.
---
 drivers/base/dd.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index d811e60610d33ae9..b25bcab2a26bd2ad 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -516,7 +516,10 @@ static int really_probe(struct device *dev, struct device_driver *drv)
 	atomic_inc(&probe_count);
 	pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 		 drv->bus->name, __func__, drv->name, dev_name(dev));
-	WARN_ON(!list_empty(&dev->devres_head));
+	if (!list_empty(&dev->devres_head)) {
+		dev_crit(dev, "Resources present before probing\n");
+		return -EBUSY;
+	}
 
 re_probe:
 	dev->driver = drv;
-- 
2.17.1