[PATCH] drm/fdinfo: Protect against driver unbind

[Tvrtko Ursulin]

If we unbind a driver from the PCI device with an active DRM client,
subsequent read of the fdinfo data associated with the file descriptor in
question will not end well.

Protect the path with a drm_dev_enter/exit() pair.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
---
 drivers/gpu/drm/drm_file.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index c299cd94d3f7..cf2463090d3a 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -964,6 +964,10 @@ void drm_show_fdinfo(struct seq_file *m, struct file *f)
 	struct drm_file *file = f->private_data;
 	struct drm_device *dev = file->minor->dev;
 	struct drm_printer p = drm_seq_file_printer(m);
+	int idx;
+
+	if (!drm_dev_enter(dev, &idx))
+		return;
 
 	drm_printf(&p, "drm-driver:\t%s\n", dev->driver->name);
 	drm_printf(&p, "drm-client-id:\t%llu\n", file->client_id);
@@ -983,6 +987,8 @@ void drm_show_fdinfo(struct seq_file *m, struct file *f)
 
 	if (dev->driver->show_fdinfo)
 		dev->driver->show_fdinfo(&p, file);
+
+	drm_dev_exit(idx);
 }
 EXPORT_SYMBOL(drm_show_fdinfo);
 
-- 
2.48.0