Re: [Outreachy kernel] [PATCH] staging: media: omap4iss: Use list_entry instead of container_of

[Julia Lawall <julia.lawall@lip6.fr>]

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On Sun, 24 Mar 2019, Himadri Pandya wrote:

>
>
> On Sun, Mar 24, 2019 at 10:48 PM Julia Lawall <julia.lawall@lip6.fr> wrote:
>
>
>       On Sun, 24 Mar 2019, Himadri Pandya wrote:
>
>       > Use list_entry instead of container_of for lists iss_buffer
>       and
>       > iss_video.
>       >
>       > Signed-off-by: Himadri Pandya <himadri18.07@gmail.com>
>       > ---
>       >  drivers/staging/media/omap4iss/iss_video.h | 4 ++--
>       >  1 file changed, 2 insertions(+), 2 deletions(-)
>       >
>       > diff --git a/drivers/staging/media/omap4iss/iss_video.h
>       b/drivers/staging/media/omap4iss/iss_video.h
>       > index f22489edb562..e8d27b7ac329 100644
>       > --- a/drivers/staging/media/omap4iss/iss_video.h
>       > +++ b/drivers/staging/media/omap4iss/iss_video.h
>       > @@ -118,7 +118,7 @@ struct iss_buffer {
>       >       dma_addr_t iss_addr;
>       >  };
>       >
>       > -#define to_iss_buffer(buf)   container_of(buf, struct
>       iss_buffer, vb)
>       > +#define to_iss_buffer(buf)   list_entry(buf, struct
>       iss_buffer, vb)
>
>       Actually, this macro is no longer used.  Perhaps someone else
>       converted
>       the uses to use the proper list operations and forgot to drop
>       the macro
>       definition.
>
>
> Then should I send a patch to drop these macros?

One of the macros is used and one is not.  You can send a patch to drop
the one that is not used.  The other one is used only once.  Still it
looks more readable than a call to container_of.

julia

>  
>
>       >
>       >  enum iss_video_dmaqueue_flags {
>       >       /* Set if DMA queue becomes empty when
>       ISS_PIPELINE_STREAM_CONTINUOUS */
>       > @@ -170,7 +170,7 @@ struct iss_video {
>       >       const struct iss_video_operations *ops;
>       >  };
>       >
>       > -#define to_iss_video(vdev)   container_of(vdev, struct
>       iss_video, video)
>       > +#define to_iss_video(vdev)   list_entry(vdev, struct
>       iss_video, video)
>
>       This doesn't involve a list.  Nor does the previous one.  To use
>       list_entry, the third argument should be the name of a field
>       that has type
>       list_head.
>
>
> Understood. Thank you.
>
> - Himadri 
>  
>
>       julia
>
>       >  struct iss_video_fh {
>       >       struct v4l2_fh vfh;
>       > --
>       > 2.17.1
>       >
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