Re: [PATCH v3 1/3] drm: Stop spamming log with drm_cache message

["Souza, Jose" <jose.souza@intel.com>]

On Mon, 2022-01-31 at 08:59 -0800, Lucas De Marchi wrote:
> Only x86 and in some cases PPC have support added in drm_cache.c for the
> clflush class of functions. However warning once is sufficient to taint
> the log instead of spamming it with "Architecture has no drm_cache.c
> support" every few millisecond. Switch to WARN_ONCE() so we still get
> the log message, but only once, together with the warning. E.g:
> 
> 	------------[ cut here ]------------
> 	Architecture has no drm_cache.c support
> 	WARNING: CPU: 80 PID: 888 at drivers/gpu/drm/drm_cache.c:139 drm_clflush_sg+0x40/0x50 [drm]
> 	...
> 
> v2 (Jani): use WARN_ONCE() and keep the message previously on pr_err()

Reviewed-by: José Roberto de Souza <jose.souza@intel.com>

But while at it, why not add a drm_device parameter to this function so we can use drm_WARN_ONCE()?
Anyways, it is better than before.

> 
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
> 
> v3: No changes from previous version, just submitting to the right
> mailing list
> 
>  drivers/gpu/drm/drm_cache.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
> index f19d9acbe959..2c3fa5677f7e 100644
> --- a/drivers/gpu/drm/drm_cache.c
> +++ b/drivers/gpu/drm/drm_cache.c
> @@ -112,8 +112,7 @@ drm_clflush_pages(struct page *pages[], unsigned long num_pages)
>  		kunmap_atomic(page_virtual);
>  	}
>  #else
> -	pr_err("Architecture has no drm_cache.c support\n");
> -	WARN_ON_ONCE(1);
> +	WARN_ONCE(1, "Architecture has no drm_cache.c support\n");
>  #endif
>  }
>  EXPORT_SYMBOL(drm_clflush_pages);
> @@ -143,8 +142,7 @@ drm_clflush_sg(struct sg_table *st)
>  	if (wbinvd_on_all_cpus())
>  		pr_err("Timed out waiting for cache flush\n");
>  #else
> -	pr_err("Architecture has no drm_cache.c support\n");
> -	WARN_ON_ONCE(1);
> +	WARN_ONCE(1, "Architecture has no drm_cache.c support\n");
>  #endif
>  }
>  EXPORT_SYMBOL(drm_clflush_sg);
> @@ -177,8 +175,7 @@ drm_clflush_virt_range(void *addr, unsigned long length)
>  	if (wbinvd_on_all_cpus())
>  		pr_err("Timed out waiting for cache flush\n");
>  #else
> -	pr_err("Architecture has no drm_cache.c support\n");
> -	WARN_ON_ONCE(1);
> +	WARN_ONCE(1, "Architecture has no drm_cache.c support\n");
>  #endif
>  }
>  EXPORT_SYMBOL(drm_clflush_virt_range);