On 4/28/07, Tejun Heo <[email protected]> wrote:
> Implement bin_buffer which contains a mutex and pointer to PAGE_SIZE
> buffer to properly synchronize accesses to per-openfile buffer and
> prepare for immediate-kobj-disconnect.
>
> Signed-off-by: Tejun Heo <[email protected]>
> ---
> [...]
> @@ -135,14 +160,22 @@ static int open(struct inode * inode, struct file * file)
> goto Error;
>
> error = -ENOMEM;
> - file->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
> - if (!file->private_data)
> + bb = kzalloc(sizeof(*bb), GFP_KERNEL);
> + if (!bb)
> goto Error;
>
> + bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
You could simply do a __get_free_page() here instead of a kmalloc(PAGE_SIZE).
> @@ -155,11 +188,12 @@ static int release(struct inode * inode, struct file * file)
> struct kobject * kobj = to_kobj(file->f_path.dentry->d_parent);
> struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
> struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
> - u8 * buffer = file->private_data;
> + struct bin_buffer *bb = file->private_data;
>
> kobject_put(kobj);
> module_put(attr->attr.owner);
> - kfree(buffer);
> + kfree(bb->buffer);
And so this would become free_page().