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Date:   Tue, 20 Sep 2022 17:14:13 -0700
Mime-Version: 1.0
Message-ID: <20220921001414.4046492-1-isaacmanjarres@google.com>
Subject: [PATCH v1] driver core: Fix bus_type.match() error handling in __driver_attach()
From:   "Isaac J. Manjarres" <isaacmanjarres@google.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Russell King <rmk+kernel@arm.linux.org.uk>,
        Tomeu Vizoso <tomeu.vizoso@collabora.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Ulf Hansson <ulf.hansson@linaro.org>
Cc:     "Isaac J. Manjarres" <isaacmanjarres@google.com>,
        stable@vger.kernel.org, Saravana Kannan <saravanak@google.com>,
        kernel-team@android.com, linux-kernel@vger.kernel.org
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Precedence: bulk

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@vger.kernel.org
Cc: Saravana Kannan <saravanak@google.com>
Signed-off-by: Isaac J. Manjarres <isaacmanjarres@google.com>
---
 drivers/base/dd.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

This problem was not reported anywhere, but rather it was something that
I noticed while looking at this function.

--Isaac

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index ec69b43f926a..6669daf1f31f 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -1162,7 +1162,11 @@ static int __driver_attach(struct device *dev, void *data)
 		return 0;
 	} else if (ret < 0) {
 		dev_dbg(dev, "Bus failed to match device: %d\n", ret);
-		return ret;
+		/*
+		 * Driver could not match with device, but may match with
+		 * another device on the bus.
+		 */
+		return 0;
 	} /* ret > 0 means positive match */
 
 	if (driver_allows_async_probing(drv)) {
-- 
2.37.3.968.ga6b4b080e4-goog