[S390] tape: cleanup reference counting

Rename tape_get_device to tape_find_device and tape_get_device_reference
to tape_get_device. The old names didn't make too much sense.

Follow the get_device()/put_device() semantic and convert tape_put_device
to a void function.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

7 files changed, 50 insertions, 51 deletions

diff --git a/drivers/s390/char/tape.h b/drivers/s390/char/tape.h
index a26333774701..fbe41e0377b8 100644
--- a/drivers/s390/char/tape.h
+++ b/drivers/s390/char/tape.h
@@ -292,9 +292,9 @@ extern int tape_generic_pm_suspend(struct ccw_device *);
 extern int tape_generic_probe(struct ccw_device *);
 extern void tape_generic_remove(struct ccw_device *);
 
-extern struct tape_device *tape_get_device(int devindex);
-extern struct tape_device *tape_get_device_reference(struct tape_device *);
-extern struct tape_device *tape_put_device(struct tape_device *);
+extern struct tape_device *tape_find_device(int devindex);
+extern struct tape_device *tape_get_device(struct tape_device *);
+extern void tape_put_device(struct tape_device *);
 
 /* Externals from tape_char.c */
 extern int tapechar_init(void);
diff --git a/drivers/s390/char/tape_34xx.c b/drivers/s390/char/tape_34xx.c
index 2fe45ff77b75..3657fe103c27 100644
--- a/drivers/s390/char/tape_34xx.c
+++ b/drivers/s390/char/tape_34xx.c
@@ -113,16 +113,16 @@ tape_34xx_work_handler(struct work_struct *work)
 {
         struct tape_34xx_work *p =
                 container_of(work, struct tape_34xx_work, work);
+        struct tape_device *device = p->device;
 
         switch(p->op) {
                 case TO_MSEN:
-                        tape_34xx_medium_sense(p->device);
+                        tape_34xx_medium_sense(device);
                         break;
                 default:
                         DBF_EVENT(3, "T34XX: internal error: unknown work\n");
         }
-
-        p->device = tape_put_device(p->device);
+        tape_put_device(device);
         kfree(p);
 }
 
@@ -136,7 +136,7 @@ tape_34xx_schedule_work(struct tape_device *device, enum tape_op op)
 
         INIT_WORK(&p->work, tape_34xx_work_handler);
 
-        p->device = tape_get_device_reference(device);
+        p->device = tape_get_device(device);
         p->op     = op;
 
         schedule_work(&p->work);
diff --git a/drivers/s390/char/tape_3590.c b/drivers/s390/char/tape_3590.c
index e4cc3aae9162..0c72aadb8391 100644
--- a/drivers/s390/char/tape_3590.c
+++ b/drivers/s390/char/tape_3590.c
@@ -608,7 +608,7 @@ tape_3590_schedule_work(struct tape_device *device, enum tape_op op)
 
         INIT_WORK(&p->work, tape_3590_work_handler);
 
-        p->device = tape_get_device_reference(device);
+        p->device = tape_get_device(device);
         p->op = op;
 
         schedule_work(&p->work);
diff --git a/drivers/s390/char/tape_block.c b/drivers/s390/char/tape_block.c
index 0c0705b91c28..c97c6aac8ed5 100644
--- a/drivers/s390/char/tape_block.c
+++ b/drivers/s390/char/tape_block.c
@@ -239,7 +239,7 @@ tapeblock_setup_device(struct tape_device * device)
         disk->major = tapeblock_major;
         disk->first_minor = device->first_minor;
         disk->fops = &tapeblock_fops;
-        disk->private_data = tape_get_device_reference(device);
+        disk->private_data = tape_get_device(device);
         disk->queue = blkdat->request_queue;
         set_capacity(disk, 0);
         sprintf(disk->disk_name, "btibm%d",
@@ -247,11 +247,11 @@ tapeblock_setup_device(struct tape_device * device)
 
         blkdat->disk = disk;
         blkdat->medium_changed = 1;
-        blkdat->request_queue->queuedata = tape_get_device_reference(device);
+        blkdat->request_queue->queuedata = tape_get_device(device);
 
         add_disk(disk);
 
-        tape_get_device_reference(device);
+        tape_get_device(device);
         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 
         return 0;
@@ -274,13 +274,14 @@ tapeblock_cleanup_device(struct tape_device *device)
         }
 
         del_gendisk(device->blk_data.disk);
-        device->blk_data.disk->private_data =
-                tape_put_device(device->blk_data.disk->private_data);
+        device->blk_data.disk->private_data = NULL;
+        tape_put_device(device);
         put_disk(device->blk_data.disk);
 
         device->blk_data.disk = NULL;
 cleanup_queue:
-        device->blk_data.request_queue->queuedata = tape_put_device(device);
+        device->blk_data.request_queue->queuedata = NULL;
+        tape_put_device(device);
 
         blk_cleanup_queue(device->blk_data.request_queue);
         device->blk_data.request_queue = NULL;
@@ -363,7 +364,7 @@ tapeblock_open(struct block_device *bdev, fmode_t mode)
         struct tape_device *    device;
         int                     rc;
 
-        device = tape_get_device_reference(disk->private_data);
+        device = tape_get_device(disk->private_data);
 
         if (device->required_tapemarks) {
                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
diff --git a/drivers/s390/char/tape_char.c b/drivers/s390/char/tape_char.c
index b47e20d3d1da..d44e6981eeac 100644
--- a/drivers/s390/char/tape_char.c
+++ b/drivers/s390/char/tape_char.c
@@ -286,9 +286,9 @@ tapechar_open (struct inode *inode, struct file *filp)
 
         lock_kernel();
         minor = iminor(filp->f_path.dentry->d_inode);
-        device = tape_get_device(minor / TAPE_MINORS_PER_DEV);
+        device = tape_find_device(minor / TAPE_MINORS_PER_DEV);
         if (IS_ERR(device)) {
-                DBF_EVENT(3, "TCHAR:open: tape_get_device() failed\n");
+                DBF_EVENT(3, "TCHAR:open: tape_find_device() failed\n");
                 rc = PTR_ERR(device);
                 goto out;
         }
@@ -340,7 +340,8 @@ tapechar_release(struct inode *inode, struct file *filp)
                 device->char_data.idal_buf = NULL;
         }
         tape_release(device);
-        filp->private_data = tape_put_device(device);
+        filp->private_data = NULL;
+        tape_put_device(device);
 
         return 0;
 }
diff --git a/drivers/s390/char/tape_core.c b/drivers/s390/char/tape_core.c
index 6311018e6543..a7b7e72c691b 100644
--- a/drivers/s390/char/tape_core.c
+++ b/drivers/s390/char/tape_core.c
@@ -511,11 +511,12 @@ tape_alloc_device(void)
  * increment the reference count.
  */
 struct tape_device *
-tape_get_device_reference(struct tape_device *device)
+tape_get_device(struct tape_device *device)
 {
-        DBF_EVENT(4, "tape_get_device_reference(%p) = %i\n", device,
-                atomic_inc_return(&device->ref_count));
+        int count;
 
+        count = atomic_inc_return(&device->ref_count);
+        DBF_EVENT(4, "tape_get_device(%p) = %i\n", device, count);
         return device;
 }
 
@@ -525,32 +526,25 @@ tape_get_device_reference(struct tape_device *device)
  * The function returns a NULL pointer to be used by the caller
  * for clearing reference pointers.
  */
-struct tape_device *
+void
 tape_put_device(struct tape_device *device)
 {
-        int remain;
+        int count;
 
-        remain = atomic_dec_return(&device->ref_count);
-        if (remain > 0) {
-                DBF_EVENT(4, "tape_put_device(%p) -> %i\n", device, remain);
-        } else {
-                if (remain < 0) {
-                        DBF_EVENT(4, "put device without reference\n");
-                } else {
-                        DBF_EVENT(4, "tape_free_device(%p)\n", device);
-                        kfree(device->modeset_byte);
-                        kfree(device);
-                }
+        count = atomic_dec_return(&device->ref_count);
+        DBF_EVENT(4, "tape_put_device(%p) -> %i\n", device, count);
+        BUG_ON(count < 0);
+        if (count == 0) {
+                kfree(device->modeset_byte);
+                kfree(device);
         }
-
-        return NULL;                    
 }
 
 /*
  * Find tape device by a device index.
  */
 struct tape_device *
-tape_get_device(int devindex)
+tape_find_device(int devindex)
 {
         struct tape_device *device, *tmp;
 
@@ -558,7 +552,7 @@ tape_get_device(int devindex)
         read_lock(&tape_device_lock);
         list_for_each_entry(tmp, &tape_device_list, node) {
                 if (tmp->first_minor / TAPE_MINORS_PER_DEV == devindex) {
-                        device = tape_get_device_reference(tmp);
+                        device = tape_get_device(tmp);
                         break;
                 }
         }
@@ -607,7 +601,8 @@ __tape_discard_requests(struct tape_device *device)
                 list_del(&request->list);
 
                 /* Decrease ref_count for removed request. */
-                request->device = tape_put_device(device);
+                request->device = NULL;
+                tape_put_device(device);
                 request->rc = -EIO;
                 if (request->callback != NULL)
                         request->callback(request, request->callback_data);
@@ -665,9 +660,11 @@ tape_generic_remove(struct ccw_device *cdev)
                         tape_cleanup_device(device);
         }
 
-        if (dev_get_drvdata(&cdev->dev)) {
+        device = dev_get_drvdata(&cdev->dev);
+        if (device) {
                 sysfs_remove_group(&cdev->dev.kobj, &tape_attr_group);
-                dev_set_drvdata(&cdev->dev, tape_put_device(dev_get_drvdata(&cdev->dev)));
+                dev_set_drvdata(&cdev->dev, NULL);
+                tape_put_device(device);
         }
 }
 
@@ -722,9 +719,8 @@ tape_free_request (struct tape_request * request)
 {
         DBF_LH(6, "Free request %p\n", request);
 
-        if (request->device != NULL) {
-                request->device = tape_put_device(request->device);
-        }
+        if (request->device)
+                tape_put_device(request->device);
         kfree(request->cpdata);
         kfree(request->cpaddr);
         kfree(request);
@@ -839,7 +835,8 @@ static void tape_long_busy_timeout(unsigned long data)
         BUG_ON(request->status != TAPE_REQUEST_LONG_BUSY);
         DBF_LH(6, "%08x: Long busy timeout.\n", device->cdev_id);
         __tape_start_next_request(device);
-        device->lb_timeout.data = (unsigned long) tape_put_device(device);
+        device->lb_timeout.data = 0UL;
+        tape_put_device(device);
         spin_unlock_irq(get_ccwdev_lock(device->cdev));
 }
 
@@ -919,7 +916,7 @@ __tape_start_request(struct tape_device *device, struct tape_request *request)
         }
 
         /* Increase use count of device for the added request. */
-        request->device = tape_get_device_reference(device);
+        request->device = tape_get_device(device);
 
         if (list_empty(&device->req_queue)) {
                 /* No other requests are on the queue. Start this one. */
@@ -1118,8 +1115,8 @@ __tape_do_irq (struct ccw_device *cdev, unsigned long intparm, struct irb *irb)
                 if (req->status == TAPE_REQUEST_LONG_BUSY) {
                         DBF_EVENT(3, "(%08x): del timer\n", device->cdev_id);
                         if (del_timer(&device->lb_timeout)) {
-                                device->lb_timeout.data = (unsigned long)
-                                        tape_put_device(device);
+                                device->lb_timeout.data = 0UL;
+                                tape_put_device(device);
                                 __tape_start_next_request(device);
                         }
                         return;
@@ -1174,7 +1171,7 @@ __tape_do_irq (struct ccw_device *cdev, unsigned long intparm, struct irb *irb)
                         break;
                 case TAPE_IO_LONG_BUSY:
                         device->lb_timeout.data =
-                                (unsigned long)tape_get_device_reference(device);
+                                (unsigned long) tape_get_device(device);
                         device->lb_timeout.expires = jiffies +
                                 LONG_BUSY_TIMEOUT * HZ;
                         DBF_EVENT(3, "(%08x): add timer\n", device->cdev_id);
@@ -1327,7 +1324,7 @@ EXPORT_SYMBOL(tape_generic_online);
 EXPORT_SYMBOL(tape_generic_offline);
 EXPORT_SYMBOL(tape_generic_pm_suspend);
 EXPORT_SYMBOL(tape_put_device);
-EXPORT_SYMBOL(tape_get_device_reference);
+EXPORT_SYMBOL(tape_get_device);
 EXPORT_SYMBOL(tape_state_verbose);
 EXPORT_SYMBOL(tape_op_verbose);
 EXPORT_SYMBOL(tape_state_set);
diff --git a/drivers/s390/char/tape_proc.c b/drivers/s390/char/tape_proc.c
index 202f42132939..ebd820ccfb24 100644
--- a/drivers/s390/char/tape_proc.c
+++ b/drivers/s390/char/tape_proc.c
@@ -45,7 +45,7 @@ static int tape_proc_show(struct seq_file *m, void *v)
                 seq_printf(m, "TapeNo\tBusID      CuType/Model\t"
                         "DevType/Model\tBlkSize\tState\tOp\tMedState\n");
         }
-        device = tape_get_device(n);
+        device = tape_find_device(n);
         if (IS_ERR(device))
                 return 0;
         spin_lock_irq(get_ccwdev_lock(device->cdev));