hwmon: (max1111) Fix race condition causing NULL pointer exception (d3f684f2) · Commits · 戴 / test

drivers/hwmon/max1111.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -40,6 +40,8 @@ struct max1111_data {
		struct spi_transfer xfer[2];
		uint8_t *tx_buf;
		uint8_t *rx_buf;
		struct mutex drvdata_lock;
		/* protect msg, xfer and buffers from multiple access */
		};

		static int max1111_read(struct device *dev, int channel)
		@@ -48,6 +50,9 @@ static int max1111_read(struct device *dev, int channel)
		uint8_t v1, v2;
		int err;

		/* writing to drvdata struct is not thread safe, wait on mutex */
		mutex_lock(&data->drvdata_lock);

		data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) \|
		MAX1111_CTRL_PD0 \| MAX1111_CTRL_PD1 \|
		MAX1111_CTRL_SGL \| MAX1111_CTRL_UNI \| MAX1111_CTRL_STR;
		@@ -55,12 +60,15 @@ static int max1111_read(struct device *dev, int channel)
		err = spi_sync(data->spi, &data->msg);
		if (err < 0) {
		dev_err(dev, "spi_sync failed with %d\n", err);
		mutex_unlock(&data->drvdata_lock);
		return err;
		}

		v1 = data->rx_buf[0];
		v2 = data->rx_buf[1];

		mutex_unlock(&data->drvdata_lock);

		if ((v1 & 0xc0) \|\| (v2 & 0x3f))
		return -EINVAL;

		@@ -176,6 +184,8 @@ static int __devinit max1111_probe(struct spi_device *spi)
		if (err)
		goto err_free_data;

		mutex_init(&data->drvdata_lock);

		data->spi = spi;
		spi_set_drvdata(spi, data);

		@@ -213,6 +223,7 @@ static int __devexit max1111_remove(struct spi_device *spi)

		hwmon_device_unregister(data->hwmon_dev);
		sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
		mutex_destroy(&data->drvdata_lock);
		kfree(data->rx_buf);
		kfree(data->tx_buf);
		kfree(data);