[Intel-gfx] [PATCH] drm/i915: Build request info on stack before printk

[Chris Wilson]

Quoting Chris Wilson (2018-04-24 02:08:39)
> printk unhelpfully inserts a '\n' between consecutive calls, and since
> our drm_printf wrapper may be emitting info a seq_file instead,
> KERN_CONT is not an option. To work with any drm_printf destination, we
> need to build up the output into a temporary buf on the stack and then
> feed the complete line in a single call to printk.
> 
> Fixes: b7268c5eed0a ("drm/i915: Pack params to engine->schedule() into a struct")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> ---

I put back the i915 parameter as it makes later patches easier. The
conflict in rebasing was a reminder why it was there in the first place.
-Chris

>  drivers/gpu/drm/i915/intel_engine_cs.c | 24 +++++++++++++++---------
>  1 file changed, 15 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index be608f7111f5..66cddd059666 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -1113,14 +1113,17 @@ unsigned int intel_engines_has_context_isolation(struct drm_i915_private *i915)
>         return which;
>  }
>  
> -static void print_sched_attr(struct drm_printer *m,
> -                            const struct drm_i915_private *i915,
> -                            const struct i915_sched_attr *attr)
> +static int print_sched_attr(struct drm_i915_private *i915,
> +                           const struct i915_sched_attr *attr,
> +                           char *buf, int x, int len)
>  {
>         if (attr->priority == I915_PRIORITY_INVALID)
> -               return;
> +               return x;
> +
> +       x += snprintf(buf + x, len - x,
> +                     " prio=%d", attr->priority);
>  
> -       drm_printf(m, "prio=%d", attr->priority);
> +       return x;
>  }
>  
>  static void print_request(struct drm_printer *m,
> @@ -1128,14 +1131,17 @@ static void print_request(struct drm_printer *m,
>                           const char *prefix)
>  {
>         const char *name = rq->fence.ops->get_timeline_name(&rq->fence);
> +       char buf[80];
> +       int x = 0;
> +
> +       x = print_sched_attr(rq->i915, &rq->sched.attr, buf, x, sizeof(buf));
>  
> -       drm_printf(m, "%s%x%s [%llx:%x] ",
> +       drm_printf(m, "%s%x%s [%llx:%x]%s @ %dms: %s\n",
>                    prefix,
>                    rq->global_seqno,
>                    i915_request_completed(rq) ? "!" : "",
> -                  rq->fence.context, rq->fence.seqno);
> -       print_sched_attr(m, rq->i915, &rq->sched.attr);
> -       drm_printf(m, " @ %dms: %s\n",
> +                  rq->fence.context, rq->fence.seqno,
> +                  buf,
>                    jiffies_to_msecs(jiffies - rq->emitted_jiffies),
>                    name);
>  }
> -- 
> 2.17.0
>