diff options
| author | Tom Van Braeckel <tomvanbraeckel@gmail.com> | 2015-03-31 16:39:21 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-04-03 16:15:30 +0200 |
| commit | 0b509d8d336eef6d622d66b3ae2a1fc3a072bf92 (patch) | |
| tree | 581850695df4a3fb3ee009513ee5afed7317593c /drivers/char | |
| parent | 16c9c8e1ae228e89b66cbc03ec6c753ee44d39bc (diff) | |
misc: pass miscdevice through file's private_data
Make the miscdevice accessible through the file's private_data.
Previously, this was done only when an open() file operation had been
registered. If no custom open() file operation was defined,
private_data was set to NULL.
This subtle quirk was confusing, to the point where kernel code
registered *empty* file open operations to have private_data point to
the misc device structure and avoid duplicating that logic.
And it could easily lead to bugs, where the addition or removal of a
custom open() file operation surprisingly changes the initial value of
a file's private_data structure.
To resolve this, we now place the miscdevice in the file's private_data
member unconditionally when open() is called.
Signed-off-by: Tom Van Braeckel <tomvanbraeckel@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/misc.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/char/misc.c b/drivers/char/misc.c index 5bb3a2109ab7..9fd5a91e0d81 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -140,12 +140,17 @@ static int misc_open(struct inode * inode, struct file * file) goto fail; } + /* + * Place the miscdevice in the file's + * private_data so it can be used by the + * file operations, including f_op->open below + */ + file->private_data = c; + err = 0; replace_fops(file, new_fops); - if (file->f_op->open) { - file->private_data = c; + if (file->f_op->open) err = file->f_op->open(inode,file); - } fail: mutex_unlock(&misc_mtx); return err; |