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

Chris Wright
2009-04-23T07:45:57Z

[-- Attachment #1: dm-target-use-module-refcount-directly.patch --]
[-- Type: text/plain, Size: 1880 bytes --]

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

From: Cheng Renquan <crquan@gmail.com>

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@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>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
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);