Re: [PATCH 07/13] drm/i915: Introduce dedicated object VMA iterator

Tvrtko Ursulin
2016-01-08T13:29:16Z

On 08/01/16 11:29, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> Purpose is to catch places which iterate the object VMA list
> without holding the big lock.
>
> Implemented by open coding list_for_each_entry to make the
> macro compatible with existing call sites.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 8 ++++----
> drivers/gpu/drm/i915/i915_drv.h | 6 ++++++
> drivers/gpu/drm/i915/i915_gem.c | 24 ++++++++++++------------
> drivers/gpu/drm/i915/i915_gem_gtt.c | 2 +-
> drivers/gpu/drm/i915/i915_gem_shrinker.c | 2 +-
> drivers/gpu/drm/i915/i915_gpu_error.c | 4 ++--
> 6 files changed, 26 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 714a45cf8a51..d7c2a3201161 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -117,7 +117,7 @@ static u64 i915_gem_obj_total_ggtt_size(struct drm_i915_gem_object *obj)
> u64 size = 0;
> struct i915_vma *vma;
>
> - list_for_each_entry(vma, &obj->vma_list, vma_link) {
> + i915_gem_obj_for_each_vma(vma, obj) {
> if (i915_is_ggtt(vma->vm) &&
> drm_mm_node_allocated(&vma->node))
> size += vma->node.size;
> @@ -155,7 +155,7 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
> obj->madv == I915_MADV_DONTNEED ? " purgeable" : "");
> if (obj->base.name)
> seq_printf(m, " (name: %d)", obj->base.name);
> - list_for_each_entry(vma, &obj->vma_list, vma_link) {
> + i915_gem_obj_for_each_vma(vma, obj) {
> if (vma->pin_count > 0)
> pin_count++;
> }
> @@ -164,7 +164,7 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
> seq_printf(m, " (display)");
> if (obj->fence_reg != I915_FENCE_REG_NONE)
> seq_printf(m, " (fence: %d)", obj->fence_reg);
> - list_for_each_entry(vma, &obj->vma_list, vma_link) {
> + i915_gem_obj_for_each_vma(vma, obj) {
> seq_printf(m, " (%sgtt offset: %08llx, size: %08llx",
> i915_is_ggtt(vma->vm) ? "g" : "pp",
> vma->node.start, vma->node.size);
> @@ -342,7 +342,7 @@ static int per_file_stats(int id, void *ptr, void *data)
> stats->shared += obj->base.size;
>
> if (USES_FULL_PPGTT(obj->base.dev)) {
> - list_for_each_entry(vma, &obj->vma_list, vma_link) {
> + i915_gem_obj_for_each_vma(vma, obj) {
> struct i915_hw_ppgtt *ppgtt;
>
> if (!drm_mm_node_allocated(&vma->node))
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index b77a5d84eac2..0406a020dfcc 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2852,6 +2852,12 @@ struct drm_i915_gem_object *i915_gem_object_create_from_data(
> void i915_gem_free_object(struct drm_gem_object *obj);
> void i915_gem_vma_destroy(struct i915_vma *vma);
>
> +#define i915_gem_obj_for_each_vma(vma, obj) \
> + for (WARN_ON_ONCE(!mutex_is_locked(&(obj)->base.dev->struct_mutex)), \
> + vma = list_first_entry(&(obj)->vma_list, typeof(*vma), vma_link);\
> + &vma->vma_link != (&(obj)->vma_list); \
> + vma = list_next_entry(vma, vma_link))
> +

Unfortunately error capture is not happy with this approach. Can't even
see that error capture attempts to grab the mutex anywhere.

So what? Drop the idea or add a "doing error capture" flag somewhere?

Regards,

Tvrtko