On 18/02/2022 03:47, Kasireddy, Vivek wrote:
Hi Tvrtko,
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?
[Kasireddy, Vivek] Partly, yes; but I figured since we are anyway doing
if (!entry || ..), it makes sense to dereference entry and extract the rb_node
after this check.
Unless I am blind I don't see that it makes a difference.
"&entry->rb_hole_addr" is taking an address of, which works "fine" is
entry is NULL. And does not get past the !entry check for the actual
de-reference via RB_EMPTY_NODE. With your patch you move that after the
!entry check but still have it in the RB_EMPTY_NODE macro. Again, unless
I am blind, I think just drop this patch.
Regards,
Tvrtko
Thanks,
Vivek
Regards,
Tvrtko
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
---
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)) \
