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 <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Cc: Christian König <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: Sumit Semwal <[email protected]>
Cc: [email protected]
Reviewed-by: Christian König <[email protected]>
---
This, this is v2. Not the old branch; remember to check the git
send-email before hitting enter.
-Chris
---
 drivers/dma-buf/reservation.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index 4d32e2c67862..4447e13d1e89 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -365,6 +365,10 @@ int reservation_object_get_fences_rcu(struct 
reservation_object *obj,
                                           GFP_NOWAIT | __GFP_NOWARN);
                        if (!nshared) {
                                rcu_read_unlock();
+
+                               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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