Op 13-08-2021 om 22:30 schreef Daniel Vetter:
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 lookupexcept we have the conversion from idr to xarray in between.
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 | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 005b1cec7007..e37fac8fac0c 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1881,11 +1881,11 @@ 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;
I think this could be a plain i915_vm_get now, kref_get_unless_zero is not guarded by RCU any more.
- rcu_read_unlock();
xa_unlock(&file_priv->vm_xa);
return vm;
}
Apart from that, all looks good.
With this fix, for patch 2-11:
Reviewed-by: Maarten Lankhorst maarten.lankhorst@linux.intel.com