[S390] vmur: Use wait queue instead of mutex to serialize open
If user space opens a unit record device node then vmur is leaving the kernel
with lock open_mutex still held to prevent other processes from opening the
device simultaneously. This causes lockdep to complain about a lock held when
returning to user space.
Now the mutex is replaced by a wait queue to serialize device open.
Signed-off-by: Frank Munzert <munzert@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/drivers/s390/char/vmur.h b/drivers/s390/char/vmur.h
index fa95964..fa320ad 100644
--- a/drivers/s390/char/vmur.h
+++ b/drivers/s390/char/vmur.h
@@ -62,7 +62,6 @@
struct urdev {
struct ccw_device *cdev; /* Backpointer to ccw device */
struct mutex io_mutex; /* Serialises device IO */
- struct mutex open_mutex; /* Serialises access to device */
struct completion *io_done; /* do_ur_io waits; irq completes */
struct device *device;
struct cdev *char_device;
@@ -71,6 +70,9 @@
int class; /* VM device class */
int io_request_rc; /* return code from I/O request */
atomic_t ref_count; /* reference counter */
+ wait_queue_head_t wait; /* wait queue to serialize open */
+ int open_flag; /* "urdev is open" flag */
+ spinlock_t open_lock; /* serialize critical sections */
};
/*