2021-04-24 14:56:50

by Guenter Roeck

Subject: [PATCH v2] usb: gadget: Drop unnecessary NULL checks after container_of

The parameters passed to allow_link and drop_link functions are never NULL.
That means the result of container_of() on those parameters is also
never NULL, even though the reference into the structure points to the
first element of the structure. Remove the unnecessary NULL checks.

This change was made automatically with the following Coccinelle script.
A now obsolete 'out:' label was removed manually.

@@
type t;
identifier v;
statement s;
@@

<+...
(
t v = container_of(...);
|
v = container_of(...);
)
...
when != v
- if (\( !v \| v == NULL \) ) s
...+>

Cc: Laurent Pinchart <[email protected]>
Cc: Felipe Balbi <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Acked-by: Felipe Balbi <[email protected]>
Signed-off-by: Guenter Roeck <[email protected]>
---
v2: Dropped RFC, added Acked-by:, dropped now obsolete 'out:' label

drivers/usb/gadget/function/uvc_configfs.c | 5 -----
1 file changed, 5 deletions(-)

diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
index 00fb58e50a15..7775f9902360 100644
--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -914,8 +914,6 @@ static int uvcg_streaming_header_allow_link(struct config_item *src,

target_fmt = container_of(to_config_group(target), struct uvcg_format,
group);
- if (!target_fmt)
- goto out;

uvcg_format_set_indices(to_config_group(target));

@@ -955,8 +953,6 @@ static void uvcg_streaming_header_drop_link(struct config_item *src,
mutex_lock(&opts->lock);
target_fmt = container_of(to_config_group(target), struct uvcg_format,
group);
- if (!target_fmt)
- goto out;

list_for_each_entry_safe(format_ptr, tmp, &src_hdr->formats, entry)
if (format_ptr->fmt == target_fmt) {
@@ -968,7 +964,6 @@ static void uvcg_streaming_header_drop_link(struct config_item *src,

--target_fmt->linked;

-out:
mutex_unlock(&opts->lock);
mutex_unlock(su_mutex);
}
--
2.17.1

2021-04-25 03:10:16

by Laurent Pinchart

Subject: Re: [PATCH v2] usb: gadget: Drop unnecessary NULL checks after container_of

Hi Guenter,

Thank you for the patch.

On Sat, Apr 24, 2021 at 07:54:43AM -0700, Guenter Roeck wrote:
> The parameters passed to allow_link and drop_link functions are never NULL.
> That means the result of container_of() on those parameters is also
> never NULL, even though the reference into the structure points to the
> first element of the structure. Remove the unnecessary NULL checks.
>
> This change was made automatically with the following Coccinelle script.
> A now obsolete 'out:' label was removed manually.
>
> @@
> type t;
> identifier v;
> statement s;
> @@
>
> <+...
> (
> t v = container_of(...);
> |
> v = container_of(...);
> )
> ...
> when != v
> - if (\( !v \| v == NULL \) ) s
> ...+>
>
> Cc: Laurent Pinchart <[email protected]>
> Cc: Felipe Balbi <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
> Acked-by: Felipe Balbi <[email protected]>
> Signed-off-by: Guenter Roeck <[email protected]>

Reviewed-by: Laurent Pinchart <[email protected]>

> ---
> v2: Dropped RFC, added Acked-by:, dropped now obsolete 'out:' label
>
> drivers/usb/gadget/function/uvc_configfs.c | 5 -----
> 1 file changed, 5 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
> index 00fb58e50a15..7775f9902360 100644
> --- a/drivers/usb/gadget/function/uvc_configfs.c
> +++ b/drivers/usb/gadget/function/uvc_configfs.c
> @@ -914,8 +914,6 @@ static int uvcg_streaming_header_allow_link(struct config_item *src,
>
> target_fmt = container_of(to_config_group(target), struct uvcg_format,
> group);
> - if (!target_fmt)
> - goto out;
>
> uvcg_format_set_indices(to_config_group(target));
>
> @@ -955,8 +953,6 @@ static void uvcg_streaming_header_drop_link(struct config_item *src,
> mutex_lock(&opts->lock);
> target_fmt = container_of(to_config_group(target), struct uvcg_format,
> group);
> - if (!target_fmt)
> - goto out;
>
> list_for_each_entry_safe(format_ptr, tmp, &src_hdr->formats, entry)
> if (format_ptr->fmt == target_fmt) {
> @@ -968,7 +964,6 @@ static void uvcg_streaming_header_drop_link(struct config_item *src,
>
> --target_fmt->linked;
>
> -out:
> mutex_unlock(&opts->lock);
> mutex_unlock(su_mutex);
> }

--
Regards,

Laurent Pinchart