On 17/02/2022 07:50, Vivek Kasireddy wrote:
While looking for next holes suitable for an allocation, although,
it is highly unlikely, make sure that the DECLARE_NEXT_HOLE_ADDR
macro is using a valid node before it extracts the rb_node from it.

Was the need for this just a consequence of insufficient locking in the i915 patch?

Regards,

Tvrtko


Cc: Tvrtko Ursulin <tvrtko.ursu...@linux.intel.com>
Cc: Christian König <christian.koe...@amd.com>
Signed-off-by: Vivek Kasireddy <vivek.kasire...@intel.com>
---
  drivers/gpu/drm/drm_mm.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 8257f9d4f619..499d8874e4ed 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -389,11 +389,12 @@ first_hole(struct drm_mm *mm,
  #define DECLARE_NEXT_HOLE_ADDR(name, first, last)                     \
  static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size)  \
  {                                                                     \
-       struct rb_node *parent, *node = &entry->rb_hole_addr;            \
+       struct rb_node *parent, *node;                                  \
                                                                        \
-       if (!entry || RB_EMPTY_NODE(node))                              \
+       if (!entry || RB_EMPTY_NODE(&entry->rb_hole_addr))               \
                return NULL;                                            \
                                                                        \
+       node = &entry->rb_hole_addr;                                     \
        if (usable_hole_addr(node->first, size)) {                   \
                node = node->first;                                  \
                while (usable_hole_addr(node->last, size))           \

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