linux-kernel - [PATCH v2 4/4] dma-buf: Check status of enable-signaling bit on debug

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Date:   Mon, 5 Sep 2022 22:05:02 +0530
From:   Arvind Yadav <Arvind.Yadav@....com>
To:     <Christian.Koenig@....com>, <andrey.grodzovsky@....com>,
        <shashank.sharma@....com>, <amaranath.somalapuram@....com>,
        <Arunpravin.PaneerSelvam@....com>, <sumit.semwal@...aro.org>,
        <gustavo@...ovan.org>, <airlied@...ux.ie>, <daniel@...ll.ch>,
        <linux-media@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <linaro-mm-sig@...ts.linaro.org>, <linux-kernel@...r.kernel.org>
CC:     Arvind Yadav <Arvind.Yadav@....com>
Subject: [PATCH v2 4/4] dma-buf: Check status of enable-signaling bit on debug

The core DMA-buf framework needs to enable signaling
before the fence is signaled. The core DMA-buf framework
can forget to enable signaling before the fence is signaled.
To avoid this scenario on the debug kernel, check the
DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT status bit before checking
the signaling bit status to confirm that enable_signaling
is enabled.

Signed-off-by: Arvind Yadav <Arvind.Yadav@....com>
---

Changes in v1 :
1- Addressing Christian's comment to replace
CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS.
2- As per Christian's comment moving this patch at last so
The version of this patch is also changed and previously
it was [PATCH 1/4]

---
 include/linux/dma-fence.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 775cdc0b4f24..ba1ddc14c5d4 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -428,6 +428,11 @@ dma_fence_is_signaled_locked(struct dma_fence *fence)
 static inline bool
 dma_fence_is_signaled(struct dma_fence *fence)
 {
+#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
+	if (!test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags))
+		return false;
+#endif
+
 	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 		return true;

-- 
2.25.1