From c9402efe492bb46ccbf94fedc4783eb8f8747567 Mon Sep 17 00:00:00 2001 From: Christian König Date: Wed, 29 May 2024 10:43:22 +0200 Subject: dma-buf: add a warning when drv try to reserve 0 fence slots MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When dma_resv_reserve_fences() is called with num_fences=0 it usually means that a driver or other component messed up its calculation how many fences are needed. Warn in that situation. When no fence are needed the function shouldn't be called in the first place. Signed-off-by: Christian König Link: https://patchwork.freedesktop.org/patch/msgid/20240529084322.2284-1-christian.koenig@amd.com Reviewed-by: Matthew Auld --- drivers/dma-buf/dma-resv.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index e2869fb31140..5f8d010516f0 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -186,6 +186,13 @@ int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences) dma_resv_assert_held(obj); + /* Driver and component code should never call this function with + * num_fences=0. If they do it usually points to bugs when calculating + * the number of needed fences dynamically. + */ + if (WARN_ON(!num_fences)) + return -EINVAL; + old = dma_resv_fences_list(obj); if (old && old->max_fences) { if ((old->num_fences + num_fences) <= old->max_fences) -- cgit v1.2.3