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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Mikhail Lappo <mikhail.lappo@esrlabs.com>,
        Fabio Estevam <fabio.estevam@nxp.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Dong Aisheng <aisheng.dong@nxp.com>,
        Zhang Rui <rui.zhang@intel.com>
Subject: [PATCH 4.9 56/95] thermal: imx: Fix race condition in imx_thermal_probe()
Date:   Sun, 22 Apr 2018 15:53:25 +0200
Message-Id: <20180422135212.710583834@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mikhail Lappo <mikhail.lappo@esrlabs.com>

commit cf1ba1d73a33944d8c1a75370a35434bf146b8a7 upstream.

When device boots with T > T_trip_1 and requests interrupt,
the race condition takes place. The interrupt comes before
THERMAL_DEVICE_ENABLED is set. This leads to an attempt to
reading sensor value from irq and disabling the sensor, based on
the data->mode field, which expected to be THERMAL_DEVICE_ENABLED,
but still stays as THERMAL_DEVICE_DISABLED. Afher this issue
sensor is never re-enabled, as the driver state is wrong.

Fix this problem by setting the 'data' members prior to
requesting the interrupts.

Fixes: 37713a1e8e4c ("thermal: imx: implement thermal alarm interrupt handling")
Cc: <stable@vger.kernel.org>
Signed-off-by: Mikhail Lappo <mikhail.lappo@esrlabs.com>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/thermal/imx_thermal.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/thermal/imx_thermal.c
+++ b/drivers/thermal/imx_thermal.c
@@ -587,6 +587,9 @@ static int imx_thermal_probe(struct plat
 	regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
 	regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);
 
+	data->irq_enabled = true;
+	data->mode = THERMAL_DEVICE_ENABLED;
+
 	ret = devm_request_threaded_irq(&pdev->dev, data->irq,
 			imx_thermal_alarm_irq, imx_thermal_alarm_irq_thread,
 			0, "imx_thermal", data);
@@ -598,9 +601,6 @@ static int imx_thermal_probe(struct plat
 		return ret;
 	}
 
-	data->irq_enabled = true;
-	data->mode = THERMAL_DEVICE_ENABLED;
-
 	return 0;
 }