diff options
Diffstat (limited to 'drivers/char/xillybus/xillyusb.c')
| -rw-r--r-- | drivers/char/xillybus/xillyusb.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/drivers/char/xillybus/xillyusb.c b/drivers/char/xillybus/xillyusb.c index 39bcbfd908b4..5a5afa14ca8c 100644 --- a/drivers/char/xillybus/xillyusb.c +++ b/drivers/char/xillybus/xillyusb.c @@ -184,6 +184,14 @@ struct xillyusb_dev { struct mutex process_in_mutex; /* synchronize wakeup_all() */ }; +/* + * kref_mutex is used in xillyusb_open() to prevent the xillyusb_dev + * struct from being freed during the gap between being found by + * xillybus_find_inode() and having its reference count incremented. + */ + +static DEFINE_MUTEX(kref_mutex); + /* FPGA to host opcodes */ enum { OPCODE_DATA = 0, @@ -1237,9 +1245,16 @@ static int xillyusb_open(struct inode *inode, struct file *filp) int rc; int index; + mutex_lock(&kref_mutex); + rc = xillybus_find_inode(inode, (void **)&xdev, &index); - if (rc) + if (rc) { + mutex_unlock(&kref_mutex); return rc; + } + + kref_get(&xdev->kref); + mutex_unlock(&kref_mutex); chan = &xdev->channels[index]; filp->private_data = chan; @@ -1275,8 +1290,6 @@ static int xillyusb_open(struct inode *inode, struct file *filp) ((filp->f_mode & FMODE_WRITE) && chan->open_for_write)) goto unmutex_fail; - kref_get(&xdev->kref); - if (filp->f_mode & FMODE_READ) chan->open_for_read = 1; @@ -1413,6 +1426,7 @@ unopen: return rc; unmutex_fail: + kref_put(&xdev->kref, cleanup_dev); mutex_unlock(&chan->lock); return rc; } @@ -2227,7 +2241,9 @@ static void xillyusb_disconnect(struct usb_interface *interface) xdev->dev = NULL; + mutex_lock(&kref_mutex); kref_put(&xdev->kref, cleanup_dev); + mutex_unlock(&kref_mutex); } static struct usb_driver xillyusb_driver = { |