We don't need the absolute speed of rcu for this. And i915_address_space in general dont need rcu protection anywhere else, after we've made gem contexts and engines a lot more immutable.
Note that this semantically reverts
commit aabbe344dc3ca5f7d8263a02608ba6179e8a4499 Author: Chris Wilson chris@chris-wilson.co.uk Date: Fri Aug 30 19:03:25 2019 +0100
drm/i915: Use RCU for unlocked vm_idr lookup
except we have the conversion from idr to xarray in between.
v2: kref_get_unless_zero is no longer required (Maarten)
Reviewed-by: Maarten Lankhorst maarten.lankhorst@linux.intel.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com Cc: Jon Bloomfield jon.bloomfield@intel.com Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: "Thomas Hellström" thomas.hellstrom@linux.intel.com Cc: Matthew Auld matthew.auld@intel.com Cc: Lionel Landwerlin lionel.g.landwerlin@intel.com Cc: Dave Airlie airlied@redhat.com Cc: Jason Ekstrand jason@jlekstrand.net --- drivers/gpu/drm/i915/i915_drv.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index be2392bbcecc..d89ff55d8fc8 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1874,11 +1874,11 @@ i915_gem_vm_lookup(struct drm_i915_file_private *file_priv, u32 id) { struct i915_address_space *vm;
- rcu_read_lock(); + xa_lock(&file_priv->vm_xa); vm = xa_load(&file_priv->vm_xa, id); - if (vm && !kref_get_unless_zero(&vm->ref)) - vm = NULL; - rcu_read_unlock(); + if (vm) + kref_get(&vm->ref); + xa_unlock(&file_priv->vm_xa);
return vm; }