linux-kernel - [PATCH v2 02/10] i2c: mux: pca9541: switch to i2c_lock_bus(..., I2C_LOCK

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Message-Id: <20180620051803.12206-3-peda@axentia.se>
Date:   Wed, 20 Jun 2018 07:17:55 +0200
From:   Peter Rosin <peda@...ntia.se>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Rosin <peda@...ntia.se>, Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Brian Norris <computersforpeace@...il.com>,
        Gregory Fong <gregory.0xf0@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Sekhar Nori <nsekhar@...com>,
        Kevin Hilman <khilman@...nel.org>,
        Haavard Skinnemoen <hskinnemoen@...il.com>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang@...aro.org>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Guenter Roeck <linux@...ck-us.net>, Crt Mori <cmo@...exis.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Antti Palosaari <crope@....fi>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Michael Krufky <mkrufky@...uxtv.org>,
        Lee Jones <lee.jones@...aro.org>,
        linux-integrity@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-input@...r.kernel.org, linux-media@...r.kernel.org
Subject: [PATCH v2 02/10] i2c: mux: pca9541: switch to i2c_lock_bus(..., I2C_LOCK_SEGMENT)

Locking the root adapter for __i2c_transfer will deadlock if the
device sits behind a mux-locked I2C mux. Switch to the finer-grained
i2c_lock_bus with the I2C_LOCK_SEGMENT flag. If the device does not
sit behind a mux-locked mux, the two locking variants are equivalent.

Signed-off-by: Peter Rosin <peda@...ntia.se>
---
 drivers/i2c/muxes/i2c-mux-pca9541.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c
index 6a39adaf433f..bc7c8cee5a8c 100644
--- a/drivers/i2c/muxes/i2c-mux-pca9541.c
+++ b/drivers/i2c/muxes/i2c-mux-pca9541.c
@@ -345,11 +345,11 @@ static int pca9541_probe(struct i2c_client *client,
 
 	/*
 	 * I2C accesses are unprotected here.
-	 * We have to lock the adapter before releasing the bus.
+	 * We have to lock the I2C segment before releasing the bus.
 	 */
-	i2c_lock_adapter(adap);
+	i2c_lock_bus(adap, I2C_LOCK_SEGMENT);
 	pca9541_release_bus(client);
-	i2c_unlock_adapter(adap);
+	i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
 
 	/* Create mux adapter */
 
-- 
2.11.0