[PATCH] drm: drm_printer: add __printf validation

[Eric Engestrom]

On Wednesday, 2017-02-15 15:33:18 -0800, Joe Perches wrote:
> drm_printf does not currently use the compiler to verify
> format and arguments.  Make it do so.
> 
> Miscellanea:
> 
> o Add appropriate #include files for __printf and struct va_format
> o Convert dev_printk to dev_info

I think these unrelated changes should be in 4 patches:
1 - add annotation to check the format string against the arguments
    (linux/compiler.h should be added here)
2 - add missing linux/printk.h header for struct va_format
    Note that I think a forward declaration is more appropriate here, as
    we only use pointers to this struct in this file, we never try to
    look inside. On the other hand:
3 - drm_print.c needs the header in drm_printf(), but as a separate
    patch
4 - convert dev_printk to dev_info (you need to include linux/device.h
    there)

You can add my r-b on all four patches when you send them to the list :)

Cheers,
  Eric

> 
> Signed-off-by: Joe Perches <joe at perches.com>
> ---
>  drivers/gpu/drm/drm_print.c | 2 +-
>  include/drm/drm_print.h     | 3 +++
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
> index 02a107d50706..74c466aca622 100644
> --- a/drivers/gpu/drm/drm_print.c
> +++ b/drivers/gpu/drm/drm_print.c
> @@ -36,7 +36,7 @@ EXPORT_SYMBOL(__drm_printfn_seq_file);
>  
>  void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf)
>  {
> -	dev_printk(KERN_INFO, p->arg, "[" DRM_NAME "] %pV", vaf);
> +	dev_info(p->arg, "[" DRM_NAME "] %pV", vaf);
>  }
>  EXPORT_SYMBOL(__drm_printfn_info);
>  
> diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
> index 7d98763c0444..ca4d7c6321f2 100644
> --- a/include/drm/drm_print.h
> +++ b/include/drm/drm_print.h
> @@ -26,6 +26,8 @@
>  #ifndef DRM_PRINT_H_
>  #define DRM_PRINT_H_
>  
> +#include <linux/compiler.h>
> +#include <linux/printk.h>
>  #include <linux/seq_file.h>
>  #include <linux/device.h>
>  
> @@ -75,6 +77,7 @@ void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf);
>  void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf);
>  void __drm_printfn_debug(struct drm_printer *p, struct va_format *vaf);
>  
> +__printf(2, 3)
>  void drm_printf(struct drm_printer *p, const char *f, ...);
>  
>  
> -- 
> 2.10.0.rc2.1.g053435c
>