Re: [patch] kdbus: checking for IS_ERR() instead of NULL

[David Herrmann]

Hi

On Wed, Apr 22, 2015 at 3:39 PM, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> "e->user" is never assigned an ERR_PTR().  It can be set to NULL so I
> assume that is what is intended here.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> diff --git a/ipc/kdbus/queue.c b/ipc/kdbus/queue.c
> index a449464..21fce62 100644
> --- a/ipc/kdbus/queue.c
> +++ b/ipc/kdbus/queue.c
> @@ -637,7 +637,7 @@ int kdbus_queue_entry_move(struct kdbus_queue_entry *e,
>         lockdep_assert_held(&src->lock);
>         lockdep_assert_held(&dst->lock);
>
> -       if (WARN_ON(IS_ERR(e->user)) || WARN_ON(list_empty(&e->entry)))
> +       if (WARN_ON(!e->user) || WARN_ON(list_empty(&e->entry)))

e->user is allowed to be NULL (eg., for kernel notifications). We used
to set it to ERR_PTR(foobar), but that's long gone. This WARN_ON() can
simply be dropped.

I wrote a patch [1] and will send it to Greg later.

Thanks
David

[1] http://cgit.freedesktop.org/~dvdhrm/linux/commit/?h=kdbus&id=eb132dd85d4e882a9b3ad07497b26d1b55cab893

>                 return -EINVAL;
>         if (src == dst)
>                 return 0;
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