There is a mutex already taken in disconnect.
And it even has the correct comment.
It just has to be taken in open and disconnect, too,
to prevent the race.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Oliver Neukum <[email protected]>
---
drivers/watchdog/pcwd_usb.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/drivers/watchdog/pcwd_usb.c b/drivers/watchdog/pcwd_usb.c
index 3a22291d633b..d5d68a529620 100644
--- a/drivers/watchdog/pcwd_usb.c
+++ b/drivers/watchdog/pcwd_usb.c
@@ -476,14 +476,21 @@ static long usb_pcwd_ioctl(struct file *file, unsigned int cmd,
static int usb_pcwd_open(struct inode *inode, struct file *file)
{
+ int retval = -EBUSY;
+
+ mutex_lock(&disconnect_mutex);
/* /dev/watchdog can only be opened once */
if (test_and_set_bit(0, &is_active))
- return -EBUSY;
+ goto error;
/* Activate */
usb_pcwd_start(usb_pcwd_device);
usb_pcwd_keepalive(usb_pcwd_device);
- return stream_open(inode, file);
+ retval = stream_open(inode, file);
+
+error:
+ mutex_unlock(&disconnect_mutex);
+ return retval;
}
static int usb_pcwd_release(struct inode *inode, struct file *file)
@@ -522,7 +529,13 @@ static ssize_t usb_pcwd_temperature_read(struct file *file, char __user *data,
static int usb_pcwd_temperature_open(struct inode *inode, struct file *file)
{
- return stream_open(inode, file);
+ int retval;
+
+ mutex_lock(&disconnect_mutex);
+ retval = stream_open(inode, file);
+ mutex_unlock(&disconnect_mutex);
+
+ return retval;
}
static int usb_pcwd_temperature_release(struct inode *inode, struct file *file)
--
2.40.0