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From:   Dmitry Osipenko <dmitry.osipenko@collabora.com>
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        Daniel Vetter <daniel@ffwll.ch>,
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Cc:     linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
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Subject: [PATCH v1 6/6] fastrpc: Assert held reservation lock for dma-buf mmapping
Date:   Thu, 10 Nov 2022 23:13:49 +0300
Message-Id: <20221110201349.351294-7-dmitry.osipenko@collabora.com>
In-Reply-To: <20221110201349.351294-1-dmitry.osipenko@collabora.com>
References: <20221110201349.351294-1-dmitry.osipenko@collabora.com>
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When userspace mmaps dma-buf's fd, the dma-buf reservation lock must be
held. Add locking sanity check to the dma-buf mmaping callback to ensure
that the locking assumption won't regress in the future.

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
 drivers/misc/fastrpc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 1ad580865525..0f467a71b069 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -6,6 +6,7 @@
 #include <linux/device.h>
 #include <linux/dma-buf.h>
 #include <linux/dma-mapping.h>
+#include <linux/dma-resv.h>
 #include <linux/idr.h>
 #include <linux/list.h>
 #include <linux/miscdevice.h>
@@ -682,6 +683,8 @@ static int fastrpc_mmap(struct dma_buf *dmabuf,
 	struct fastrpc_buf *buf = dmabuf->priv;
 	size_t size = vma->vm_end - vma->vm_start;
 
+	dma_resv_assert_held(dmabuf->resv);
+
 	return dma_mmap_coherent(buf->dev, vma, buf->virt,
 				 FASTRPC_PHYS(buf->phys), size);
 }
-- 
2.37.3