Currently i_cdev reference to a character device isn't accounted in the
reference count of the character device. This then requires us to track
all references through a list of all inodes referencing a character
device which is somewhat clumsy and requires list_head in each inode in
the system.
So make i_cdev a reference like any other.
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/char_dev.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/fs/char_dev.c b/fs/char_dev.c
index f77f7702fabe..518b3016ab92 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -388,12 +388,13 @@ static int chrdev_open(struct inode *inode, struct file *filp)
we dropped the lock. */
p = inode->i_cdev;
if (!p) {
+ /* Use reference from kobj_lookup for i_cdev ref */
inode->i_cdev = p = new;
list_add(&inode->i_devices, &p->list);
new = NULL;
- } else if (!cdev_get(p))
- ret = -ENXIO;
- } else if (!cdev_get(p))
+ }
+ }
+ if (!cdev_get(p))
ret = -ENXIO;
spin_unlock(&cdev_lock);
cdev_put(new);
@@ -421,10 +422,15 @@ static int chrdev_open(struct inode *inode, struct file *filp)
void cd_forget(struct inode *inode)
{
+ struct cdev *to_put;
+
spin_lock(&cdev_lock);
list_del_init(&inode->i_devices);
+ to_put = inode->i_cdev;
inode->i_cdev = NULL;
spin_unlock(&cdev_lock);
+ if (to_put)
+ cdev_put(to_put);
}
static void cdev_purge(struct cdev *cdev)
--
1.8.1.4
--
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