This changes the locking in chaoskey_read() to correctly
handle O_NONBLOCK in the case of concurrent readers.
Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
---
drivers/usb/misc/chaoskey.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index 665c75a1cdf9..ad4c0b6d02cf 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -435,9 +435,19 @@ static ssize_t chaoskey_read(struct file *file,
goto bail;
mutex_unlock(&dev->rng_lock);
- result = mutex_lock_interruptible(&dev->lock);
- if (result)
- goto bail;
+ if (file->f_flags & O_NONBLOCK) {
+ result = mutex_trylock(&dev->lock);
+ if (result == 0) {
+ result = -EAGAIN;
+ goto bail;
+ } else {
+ result = 0;
+ }
+ } else {
+ result = mutex_lock_interruptible(&dev->lock);
+ if (result)
+ goto bail;
+ }
if (dev->valid == dev->used) {
result = _chaoskey_fill(dev);
if (result < 0) {
--
2.16.4
