Re: [PATCH v3] fs/proc/base.c: fix incorrect fmode_t casts

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

On Sun, May 22, 2022 at 03:08:42PM +0300, Vasily Averin wrote:
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index c1031843cc6a..4e4edf9db5f0 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2237,13 +2237,13 @@ static struct dentry *
>  proc_map_files_instantiate(struct dentry *dentry,
>  			   struct task_struct *task, const void *ptr)
>  {
> -	fmode_t mode = (fmode_t)(unsigned long)ptr;
> +	const fmode_t *mode = ptr;

Why not ...

	fmode_t mode = *(fmode_t *)ptr;

and then you don't need

> -				    ((mode & FMODE_READ ) ? S_IRUSR : 0) |
> -				    ((mode & FMODE_WRITE) ? S_IWUSR : 0));
> +				    ((*mode & FMODE_READ ) ? S_IRUSR : 0) |
> +				    ((*mode & FMODE_WRITE) ? S_IWUSR : 0));