diff options
| author | Pavel Herrmann <morpheus.ibis@gmail.com> | 2011-07-17 20:39:19 +0400 |
|---|---|---|
| committer | Jean Delvare <khali@endymion.delvare> | 2011-07-17 20:39:19 +0400 |
| commit | d3f684f2820a7f42acef68bea6622d9032127fb2 (patch) | |
| tree | 0ca1227b9c1499093e7af42d01ad75f41481b5e1 | |
| parent | fa8b69758e65b406c8010936b541cd00deef804d (diff) | |
| download | linux-d3f684f2820a7f42acef68bea6622d9032127fb2.tar.xz | |
hwmon: (max1111) Fix race condition causing NULL pointer exception
spi_sync call uses its spi_message parameter to keep completion information,
using a drvdata structure is not thread-safe. Use a mutex to prevent
multiple access to shared driver data.
Signed-off-by: Pavel Herrmann <morpheus.ibis@gmail.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Acked-by: Cyril Hrubis <metan@ucw.cz>
Tested-by: Stanislav Brabec <utx@penguin.cz>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: stable@kernel.org
| -rw-r--r-- | drivers/hwmon/max1111.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/hwmon/max1111.c b/drivers/hwmon/max1111.c index 12a54aa29776..14335bbc9bdc 100644 --- a/drivers/hwmon/max1111.c +++ b/drivers/hwmon/max1111.c @@ -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); |