We don't want anyone but legacy DRM1 code to use drm_file.filp. Especially
for in-kernel contexts, this might be set to NULL, so lets make sure
no-one accesses it, ever.

Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
---
 drivers/gpu/drm/drm_bufs.c | 7 ++++---
 drivers/gpu/drm/drm_fops.c | 2 +-
 include/drm/drmP.h         | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c
index c3a12cd..d2803de 100644
--- a/drivers/gpu/drm/drm_bufs.c
+++ b/drivers/gpu/drm/drm_bufs.c
@@ -1456,7 +1456,7 @@ int drm_legacy_mapbufs(struct drm_device *dev, void *data,
        if (!drm_core_check_feature(dev, DRIVER_HAVE_DMA))
                return -EINVAL;

-       if (!dma)
+       if (!dma || !file_priv->legacy_filp)
                return -EINVAL;

        spin_lock(&dev->buf_lock);
@@ -1478,12 +1478,13 @@ int drm_legacy_mapbufs(struct drm_device *dev, void 
*data,
                                retcode = -EINVAL;
                                goto done;
                        }
-                       virtual = vm_mmap(file_priv->filp, 0, map->size,
+                       virtual = vm_mmap(file_priv->legacy_filp, 0, map->size,
                                          PROT_READ | PROT_WRITE,
                                          MAP_SHARED,
                                          token);
                } else {
-                       virtual = vm_mmap(file_priv->filp, 0, dma->byte_count,
+                       virtual = vm_mmap(file_priv->legacy_filp, 0,
+                                         dma->byte_count,
                                          PROT_READ | PROT_WRITE,
                                          MAP_SHARED, 0);
                }
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index e9d66f5..69ef23c 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -198,7 +198,7 @@ static int drm_open_helper(struct file *filp, struct 
drm_minor *minor)
                return -ENOMEM;

        filp->private_data = priv;
-       priv->filp = filp;
+       priv->legacy_filp = filp;
        priv->pid = get_pid(task_pid(current));
        priv->minor = minor;

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 0f69f56..2197ab1 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -330,7 +330,7 @@ struct drm_file {
        /** Lock for synchronization of access to object_idr. */
        spinlock_t table_lock;

-       struct file *filp;
+       struct file *legacy_filp; /* might be NULL! */
        void *driver_priv;

        struct drm_master *master; /* master this node is currently associated 
with
-- 
2.9.2

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