[PATCH 3/3] drm: Add a debug print for drm_modeset_backoff()

Daniel Vetter daniel at ffwll.ch
Tue Jan 22 09:41:18 UTC 2019


On Mon, Jan 21, 2019 at 10:24:30PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Logs can get confusing when some operations are done multiple times
> due to the ww mutex backoff. Add a debug print into
> drm_modeset_backoff() so that at least the reason for the odd
> looking logs will be obvious.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Makes sense. Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  drivers/gpu/drm/drm_modeset_lock.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c
> index 81dd11901ffd..1277ff18d993 100644
> --- a/drivers/gpu/drm/drm_modeset_lock.c
> +++ b/drivers/gpu/drm/drm_modeset_lock.c
> @@ -295,6 +295,8 @@ int drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx)
>  {
>  	struct drm_modeset_lock *contended = ctx->contended;
>  
> +	DRM_DEBUG_KMS("Retrying to avoid deadlock\n");
> +
>  	ctx->contended = NULL;
>  
>  	if (WARN_ON(!contended))
> -- 
> 2.19.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch


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