dm target: use module refcount directly

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@kernel.org
Signed-off-by: Cheng Renquan <crquan@gmail.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Reviewed-by: Alasdair G Kergon <agk@redhat.com>
Reviewed-by: Jonathan Brassow <jbrassow@redhat.com>

1 files changed, 3 insertions, 17 deletions

diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index 7decf10006e4..db72c9497bb4 100644
--- 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_type(const char *name)
         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_type *t)
         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_type *t)
                 BUG();
         }
 
-        if (ti->use) {
-                DMCRIT("Attempt to unregister target still in use: %s",
-                       t->name);
-                BUG();
-        }
-
         list_del(&ti->list);
         kfree(ti);