ftdev: don't hold lock while sleeping

Holding the lock prevents other tasks from opening the device.

1 files changed, 8 insertions, 1 deletions

diff --git a/litmus/ftdev.c b/litmus/ftdev.c
index 216dc0b4cb94..e282f8a9c067 100644
--- a/litmus/ftdev.c
+++ b/litmus/ftdev.c
@@ -229,13 +229,20 @@ static ssize_t ftdev_read(struct file *filp,
                          * here with copied data because that data would get
                          * lost if the task is interrupted (e.g., killed).
                          */
+                        mutex_unlock(&ftdm->lock);
                         set_current_state(TASK_INTERRUPTIBLE);
+
                         schedule_timeout(50);
+
                         if (signal_pending(current)) {
                                 if (err == 0)
                                         /* nothing read yet, signal problem */
                                         err = -ERESTARTSYS;
-                                break;
+                                goto out;
+                        }
+                        if (mutex_lock_interruptible(&ftdm->lock)) {
+                                err = -ERESTARTSYS;
+                                goto out;
                         }
                 } else if (copied < 0) {
                         /* page fault */