From 152d191ed4460723494d0c1e4b4425d4cbdf1560 Mon Sep 17 00:00:00 2001
From: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Thu, 2 Sep 2021 16:20:56 +0200
Subject: drm/i915: use xa_lock/unlock for fpriv->vm_xa lookups
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Git-commit: 843151521844af6c3e22d4bef42d292c04f05fa2
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
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>
Link: https://patchwork.freedesktop.org/patch/msgid/20210902142057.929669-10-daniel.vetter@ffwll.ch
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
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 7f6e70dd55fd..b45fd103e5d4 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1908,11 +1908,11 @@ 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;
}
--
2.38.1