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 <[email protected]> > 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. > > Signed-off-by: Daniel Vetter <[email protected]> > Cc: Jon Bloomfield <[email protected]> > Cc: Chris Wilson <[email protected]> > Cc: Maarten Lankhorst <[email protected]> > Cc: Joonas Lahtinen <[email protected]> > Cc: Daniel Vetter <[email protected]> > Cc: "Thomas Hellström" <[email protected]> > Cc: Matthew Auld <[email protected]> > Cc: Lionel Landwerlin <[email protected]> > Cc: Dave Airlie <[email protected]> > Cc: Jason Ekstrand <[email protected]> > --- > 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 <[email protected]>
