linux-kernel - [PATCH stable-4.19] driver core: Fix bus_type.match() error handling in __driver

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Message-ID: <20230110021549.1347551-1-isaacmanjarres@google.com>
Date:   Mon,  9 Jan 2023 18:15:48 -0800
From:   "Isaac J. Manjarres" <isaacmanjarres@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Russell King <rmk+kernel@....linux.org.uk>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     "Isaac J. Manjarres" <isaacmanjarres@...gle.com>,
        stable@...r.kernel.org, Saravana Kannan <saravanak@...gle.com>,
        kernel-team@...roid.com, linux-kernel@...r.kernel.org
Subject: [PATCH stable-4.19] driver core: Fix bus_type.match() error handling
 in __driver_attach()

commit 27c0d217340e47ec995557f61423ef415afba987 upstream.

When a driver registers with a bus, it will attempt to match with every
device on the bus through the __driver_attach() function. Currently, if
the bus_type.match() function encounters an error that is not
-EPROBE_DEFER, __driver_attach() will return a negative error code, which
causes the driver registration logic to stop trying to match with the
remaining devices on the bus.

This behavior is not correct; a failure while matching a driver to a
device does not mean that the driver won't be able to match and bind
with other devices on the bus. Update the logic in __driver_attach()
to reflect this.

Fixes: 656b8035b0ee ("ARM: 8524/1: driver cohandle -EPROBE_DEFER from bus_type.match()")
Cc: stable@...r.kernel.org
Cc: Saravana Kannan <saravanak@...gle.com>
Signed-off-by: Isaac J. Manjarres <isaacmanjarres@...gle.com>
---
 drivers/base/dd.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 63390a416b44..2dad29292487 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -902,8 +902,12 @@ static int __driver_attach(struct device *dev, void *data)
 		 */
 		return 0;
 	} else if (ret < 0) {
-		dev_dbg(dev, "Bus failed to match device: %d", ret);
-		return ret;
+		dev_dbg(dev, "Bus failed to match device: %d\n", ret);
+		/*
+		 * Driver could not match with device, but may match with
+		 * another device on the bus.
+		 */
+		return 0;
 	} /* ret > 0 means positive match */
 
 	if (dev->parent && dev->bus->need_parent_lock)
-- 
2.39.0.314.g84b9a713c41-goog