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From:   trix@redhat.com
To:     jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de,
        pmeerw@pmeerw.net, jmaneyrol@invensense.com,
        mirq-linux@rere.qmqm.pl, lee.jones@linaro.org
Cc:     linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
        Tom Rix <trix@redhat.com>
Subject: [PATCH] iio: imu: inv_mpu6050: check for temp_fifo_enable
Date:   Sun,  9 Aug 2020 08:59:36 -0700
Message-Id: <20200809155936.16898-1-trix@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Tom Rix <trix@redhat.com>

clang static analysis reports this problem

inv_mpu_ring.c:181:18: warning: Division by zero
        nb = fifo_count / bytes_per_datum;
             ~~~~~~~~~~~^~~~~~~~~~~~~~~~~

This is a false positive.
Dividing by 0 is protected by this check

	if (!(st->chip_config.accl_fifo_enable |
		st->chip_config.gyro_fifo_enable |
		st->chip_config.magn_fifo_enable))
		goto end_session;
	bytes_per_datum = 0;

But there is another fifo, temp_fifo

	if (st->chip_config.temp_fifo_enable)
		bytes_per_datum += INV_MPU6050_BYTES_PER_TEMP_SENSOR;

Which would be skipped if it was the only enabled fifo.
So add to the check.

Fixes: 2e4c0a5e2576 ("iio: imu: inv_mpu6050: add fifo temperature data support")

Signed-off-by: Tom Rix <trix@redhat.com>
---
 drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
index b533fa2dad0a..5240a400dcb4 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
@@ -141,6 +141,7 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
 
 	if (!(st->chip_config.accl_fifo_enable |
 		st->chip_config.gyro_fifo_enable |
+		st->chip_config.temp_fifo_enable |
 		st->chip_config.magn_fifo_enable))
 		goto end_session;
 	bytes_per_datum = 0;
-- 
2.18.1