[patch 041/100] dm target: use module refcount directly

[Chris Wright]

-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Cheng Renquan <crquan@xxxxxxxxx>

upstream commit: 5642b8a61a15436231adf27b2b1bd96901b623dd

The tt_internal's 'use' field is superfluous: the module's refcount can do
the work properly.  An acceptable side-effect is that this increases the
reference counts reported by 'lsmod'.

Remove the superfluous test when removing a target module.

[Crash possible without this on SMP - agk]

Cc: stable@xxxxxxxxxx
Signed-off-by: Cheng Renquan <crquan@xxxxxxxxx>
Signed-off-by: Alasdair G Kergon <agk@xxxxxxxxxx>
Reviewed-by: Alasdair G Kergon <agk@xxxxxxxxxx>
Reviewed-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
 drivers/md/dm-target.c |   20 +++-----------------
 1 file changed, 3 insertions(+), 17 deletions(-)

--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -18,7 +18,6 @@ struct tt_internal {
 	struct target_type tt;
 
 	struct list_head list;
-	long use;
 };
 
 static LIST_HEAD(_targets);
@@ -44,12 +43,8 @@ static struct tt_internal *get_target_ty
 	down_read(&_lock);
 
 	ti = __find_target_type(name);
-	if (ti) {
-		if ((ti->use == 0) && !try_module_get(ti->tt.module))
-			ti = NULL;
-		else
-			ti->use++;
-	}
+	if (ti && !try_module_get(ti->tt.module))
+		ti = NULL;
 
 	up_read(&_lock);
 	return ti;
@@ -77,10 +72,7 @@ void dm_put_target_type(struct target_ty
 	struct tt_internal *ti = (struct tt_internal *) t;
 
 	down_read(&_lock);
-	if (--ti->use == 0)
-		module_put(ti->tt.module);
-
-	BUG_ON(ti->use < 0);
+	module_put(ti->tt.module);
 	up_read(&_lock);
 
 	return;
@@ -140,12 +132,6 @@ void dm_unregister_target(struct target_
 		BUG();
 	}
 
-	if (ti->use) {
-		DMCRIT("Attempt to unregister target still in use: %s",
-		       t->name);
-		BUG();
-	}
-
 	list_del(&ti->list);
 	kfree(ti);
 

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