dm target: use module refcount directly

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From: Linux Kernel Mailing List
Date: Friday, April 3, 2009 - 11:08 am

Gitweb:     http://git.kernel.org/linus/5642b8a61a15436231adf27b2b1bd96901b623dd
Commit:     5642b8a61a15436231adf27b2b1bd96901b623dd
Parent:     35bf659b008e83e725dcd30f542e38461dbb867c
Author:     Cheng Renquan <crquan@gmail.com>
AuthorDate: Thu Apr 2 19:55:27 2009 +0100
Committer:  Alasdair G Kergon <agk@redhat.com>
CommitDate: Thu Apr 2 19:55:27 2009 +0100

    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>
---
 drivers/md/dm-target.c |   20 +++-----------------
 1 files changed, 3 insertions(+), 17 deletions(-)

diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index 7decf10..db72c94 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);
 
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dm target: use module refcount directly, Linux Kernel Mailing ..., (Fri Apr 3, 11:08 am)