If we have to drop the seqcount & rcu lock to perform a krealloc, we
have to restart the loop. In doing so, be careful not to lose track of
the already acquired exclusive fence.
Fixes: fedf54132d24 ("dma-buf: Restart reservation_object_get_fences_rcu() after writes") #v4.10
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/dma-buf/reservation.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index 4d32e2c67862..704503df4892 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -365,6 +365,12 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
GFP_NOWAIT | __GFP_NOWARN);
if (!nshared) {
rcu_read_unlock();
+
+ if (fence_excl) {
+ dma_fence_put(fence_excl);
+ fence_excl = NULL;
+ }
+
nshared = krealloc(shared, sz, GFP_KERNEL);
if (nshared) {
shared = nshared;
--
2.20.1
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