[PATCH 2/2] drm/i915: cleanup context fini

Ben Widawsky
2013-10-14T17:02:04Z

From: Ben Widawsky <ben@bwidawsk.net>

I had this lying around from he original PPGTT series, and thought we
might try to get it in by itself.

With the introduction of context refcounting we never explicitly
ref/unref the backing object. As such, the previous fix was a bit wonky.

Aside from fixing the above, this patch also puts us in good shape for
an upcoming patch which allows a failure to occur in between
context_init and the first do_switch.

CC: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
---
drivers/gpu/drm/i915/i915_gem_context.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 1ca1bf7..6e609c4 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -220,7 +220,6 @@ static int create_default_context(struct drm_i915_private *dev_priv)
* may not be available. To avoid this we always pin the
* default context.
*/
- dev_priv->ring[RCS].default_context = ctx;
ret = i915_gem_obj_ggtt_pin(ctx->obj, CONTEXT_ALIGN, false, false);
if (ret) {
DRM_DEBUG_DRIVER("Couldn't pin %d\n", ret);
@@ -233,6 +232,8 @@ static int create_default_context(struct drm_i915_private *dev_priv)
goto err_unpin;
}

+ dev_priv->ring[RCS].default_context = ctx;
+
DRM_DEBUG_DRIVER("Default HW context loaded\n");
return 0;

@@ -288,16 +289,24 @@ void i915_gem_context_fini(struct drm_device *dev)
* other code, leading to spurious errors. */
intel_gpu_reset(dev);

- i915_gem_object_unpin(dctx->obj);
-
/* When default context is created and switched to, base object refcount
* will be 2 (+1 from object creation and +1 from do_switch()).
* i915_gem_context_fini() will be called after gpu_idle() has switched
* to default context. So we need to unreference the base object once
* to offset the do_switch part, so that i915_gem_context_unreference()
* can then free the base object correctly. */
- drm_gem_object_unreference(&dctx->obj->base);
+ WARN_ON(!dev_priv->ring[RCS].last_context);
+ if (dev_priv->ring[RCS].last_context == dctx) {
+ /* Fake switch to NULL context */
+ WARN_ON(dctx->obj->active);
+ i915_gem_object_unpin(dctx->obj);
+ i915_gem_context_unreference(dctx);
+ }
+
+ i915_gem_object_unpin(dctx->obj);
i915_gem_context_unreference(dctx);
+ dev_priv->ring[RCS].default_context = NULL;
+ dev_priv->ring[RCS].last_context = NULL;
}

static int context_idr_cleanup(int id, void *p, void *data)
--
1.8.4