TTM, GEM, DRM or the core DMA-buf framework are needs to enable software signaling before the fence is signaled. The core DMA-buf framework software can forget to call enable_signaling before the fence is signaled. It means framework code can forget to call dma_fence_enable_sw_signaling() before calling dma_fence_is_signaled(). To avoid this scenario on debug kernel, check the DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT bit status before checking the MA_FENCE_FLAG_SIGNALED_BIT bit status to confirm that software signaling is enabled.
Arvind Yadav (4): [PATCH v2 1/4] drm/sched: Enable signaling for finished fence [PATCH v2 2/4] dma-buf: enable signaling for the stub fence on debug [PATCH v2 3/4] dma-buf: enable signaling for selftest fence on debug [PATCH v2 4/4] dma-buf: Check status of enable-signaling bit on debug
drivers/dma-buf/dma-fence.c | 7 ++++ drivers/dma-buf/st-dma-fence-chain.c | 8 +++++ drivers/dma-buf/st-dma-fence-unwrap.c | 44 ++++++++++++++++++++++++++ drivers/dma-buf/st-dma-fence.c | 25 ++++++++++++++- drivers/dma-buf/st-dma-resv.c | 20 ++++++++++++ drivers/gpu/drm/scheduler/sched_main.c | 2 ++ include/linux/dma-fence.h | 5 +++ 7 files changed, 110 insertions(+), 1 deletion(-)