[PATCH 5.4 441/453] dma-buf/dma-resv: Respect num_fences when initializing the shared fence list.

[Greg Kroah-Hartman]

From: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>

commit bf8975837dac156c33a4d15d46602700998cb6dd upstream.

We hardcode the maximum number of shared fences to 4, instead of
respecting num_fences. Use a minimum of 4, but more if num_fences
is higher.

This seems to have been an oversight when first implementing the
api.

Fixes: 04a5faa8cbe5 ("reservation: update api and add some helpers")
Cc: <stable@xxxxxxxxxxxxxxx> # v3.17+
Reported-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@xxxxxxxxx>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20201124115707.406917-1-maarten.lankhorst@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/dma-buf/dma-resv.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -161,7 +161,7 @@ int dma_resv_reserve_shared(struct dma_r
 			max = max(old->shared_count + num_fences,
 				  old->shared_max * 2);
 	} else {
-		max = 4;
+		max = max(4ul, roundup_pow_of_two(num_fences));
 	}
 
 	new = dma_resv_list_alloc(max);