linux-kernel - [PATCH v1] driver core: fw_devlink: Don't create device links for devices not on a bus

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Message-Id: <20210831224510.703253-1-saravanak@google.com>
Date:   Tue, 31 Aug 2021 15:45:10 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Saravana Kannan <saravanak@...gle.com>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        kernel-team@...roid.com, linux-kernel@...r.kernel.org
Subject: [PATCH v1] driver core: fw_devlink: Don't create device links for
 devices not on a bus

Devices that are not on a bus will never have a driver bound to it. So,
fw_devlink should not create device links for it as it can cause probe
issues[1] or sync_state() call back issues[2].

[1] - https://lore.kernel.org/lkml/CAGETcx_xJCqOWtwZ9Ee2+0sPGNLM5=F=djtbdYENkAYZa0ynqQ@mail.gmail.com/
[2] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxHHxBmQ@mail.gmail.com/
Fixes: f9aa460672c9 ("driver core: Refactor fw_devlink feature")
Reported-by: Ulf Hansson <ulf.hansson@...aro.org>
Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/base/core.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index f6360490a4a3..304a06314656 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1719,8 +1719,24 @@ static int fw_devlink_create_devlink(struct device *con,
 	struct device *sup_dev;
 	int ret = 0;
 
+	/*
+	 * If a consumer device is not on a bus (i.e. a driver will never bind
+	 * to it), it doesn't make sense for fw_devlink to create device links
+	 * for it.
+	 */
+	if (con->bus == NULL)
+		return -EINVAL;
+
 	sup_dev = get_dev_from_fwnode(sup_handle);
 	if (sup_dev) {
+		/*
+		 * If a supplier device is not on a bus (i.e. a driver will
+		 * never bind to it), it doesn't make sense for fw_devlink to
+		 * create device links for it.
+		 */
+		if (sup_dev->bus == NULL)
+			return -EINVAL;
+
 		/*
 		 * If it's one of those drivers that don't actually bind to
 		 * their device using driver core, then don't wait on this
-- 
2.33.0.259.gc128427fd7-goog