dma-buf/dma-resv: Respect num_fences when initializing the shared fence list.

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@vger.kernel.org> # v3.17+
Reported-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201124115707.406917-1-maarten.lankhorst@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 1c8f258..1187e5e 100644 (file)
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -200,7 +200,7 @@ int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
                        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);