On Mon, 9 Sep 2019 from Gerd Hoffmann <kraxel@xxxxxxxxxx>
>
> Hmm, I think the patch is wrong.
Hmm...it should have added change only in the error path, leaving locks
for drivers to release if job is done with no error returned.
> As far I know it is the qxl drivers's
> job to call ttm_eu_backoff_reservation().
Like other drivers, qxl is currently doing the right.
> Doing that automatically in
> ttm will most likely break other ttm users.
>
You are right. They are responsible for doing backoff if error happens
while validating buffers afterwards.
--- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
+++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
@@ -111,8 +111,10 @@ int ttm_eu_reserve_buffers(struct ww_acq
list_for_each_entry(entry, list, head) {
struct ttm_buffer_object *bo = entry->bo;
+ bool lockon;
ret = __ttm_bo_reserve(bo, intr, (ticket == NULL), ticket);
+ lockon = !ret;
if (!ret && unlikely(atomic_read(&bo->cpu_writers) > 0)) {
reservation_object_unlock(bo->resv);
@@ -151,6 +153,7 @@ int ttm_eu_reserve_buffers(struct ww_acq
ret = 0;
}
}
+ lockon = !ret;
if (!ret && entry->num_shared)
ret = reservation_object_reserve_shared(bo->resv,
@@ -163,6 +166,8 @@ int ttm_eu_reserve_buffers(struct ww_acq
ww_acquire_done(ticket);
ww_acquire_fini(ticket);
}
+ if (lockon)
+ ttm_eu_backoff_reservation_reverse(list, entry);
return ret;
}
--
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