Re: [PATCH RFC 14/20] proc: store cookie in private data

[Jan Kara <jack@suse.cz>]

On Fri 30-08-24 15:04:55, Christian Brauner wrote:
> Store the cookie to detect concurrent seeks on directories in
> file->private_data.
> 
> Signed-off-by: Christian Brauner <brauner@kernel.org>

...

>  	ns = proc_pid_ns(inode->i_sb);
> -	tid = (int)file->f_version;
> -	file->f_version = 0;
> +	tid = (int)(intptr_t)file->private_data;

What's the point of first casting to intptr_t?

> @@ -3890,7 +3890,7 @@ static int proc_task_readdir(struct file *file, struct dir_context *ctx)
>  				proc_task_instantiate, task, NULL)) {
>  			/* returning this tgid failed, save it as the first
>  			 * pid for the next readir call */
> -			file->f_version = (u64)tid;
> +			file->private_data = (void *)(intptr_t)tid;

The same here...

>  			put_task_struct(task);
>  			break;
>  		}
> @@ -3915,6 +3915,12 @@ static int proc_task_getattr(struct mnt_idmap *idmap,
>  	return 0;
>  }
>  
> +static loff_t proc_dir_llseek(struct file *file, loff_t offset, int whence)
> +{
> +	return generic_llseek_cookie(file, offset, whence,
> +				     (u64 *)(uintptr_t)&file->private_data);

So this I think is wrong for 32-bit archs because generic_llseek_cookie()
will store 8 bytes there while file->private_data has only 4 bytes...

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR