The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From bf8975837dac156c33a4d15d46602700998cb6dd Mon Sep 17 00:00:00 2001

From: Maarten Lankhorst maarten.lankhorst@linux.intel.com Date: Tue, 24 Nov 2020 12:57:07 +0100 Subject: [PATCH] dma-buf/dma-resv: Respect num_fences when initializing the shared fence list. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

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-maarte...

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index bb5a42b10c29..6ddbeb5dfbf6 100644 --- 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);