taos_get_lux() calls mutex_trylock(). If the lock could not be acquired,
then chip->als_cur_info.lux is returned. The issue is that this value
is updated while the mutex is held and could cause a half written value
to be returned to the caller. This patch changes the call to
mutex_trylock() with mutex_lock().
Signed-off-by: Brian Masney <masneyb@xxxxxxxxxxxxx>
---
This is the most controversial change in my patch set. There are two
other possible solutions that I could envision to work around this
issue:
1) Return -EBUSY and make the caller responsible for backing off
2) Change this driver to use RCU instead of a mutex
drivers/staging/iio/light/tsl2583.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/staging/iio/light/tsl2583.c b/drivers/staging/iio/light/tsl2583.c
index 47656ae..c4d2e3a 100644
--- a/drivers/staging/iio/light/tsl2583.c
+++ b/drivers/staging/iio/light/tsl2583.c
@@ -206,10 +206,7 @@ static int taos_get_lux(struct iio_dev *indio_dev)
u32 ch0lux = 0;
u32 ch1lux = 0;
- if (mutex_trylock(&chip->als_mutex) == 0) {
- dev_info(&chip->client->dev, "taos_get_lux device is busy\n");
- return chip->als_cur_info.lux; /* busy, so return LAST VALUE */
- }
+ mutex_lock(&chip->als_mutex);
if (chip->taos_chip_status != TSL258X_CHIP_WORKING) {
/* device is not enabled */
--
2.7.4
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