[PATCH] drm: fix case where panic notifier isn't unregistered

[Frank Binns]

The framebuffer helper panic notifier is unregistered, in drm_fb_helper_fini(), when kernel_fb_helper_list goes from being non-empty to empty. However, in drm_fb_helper_single_fb_probe(), it's possible for the panic notifier to be registered without an element being added to this list if a driver's probe function returns 0. Make sure that an attempt to add the panic notifier is made only when adding an element to kernel_fb_helper_list.

Signed-off-by: Frank Binns <frank.binns at imgtec.com>
---
drivers/gpu/drm/drm_fb_helper.c |   21 ++++++++++-----------
1 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index a0d6e89..d3764b3 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -807,21 +807,20 @@ int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
                               printk(KERN_INFO "fb%d: %s frame buffer device\n", info->node,
                                      info->fix.id);
+                             /* Switch back to kernel console on panic */
+                             /* multi card linked list maybe */
+                             if (list_empty(&kernel_fb_helper_list)) {
+                                             printk(KERN_INFO "drm: registered panic notifier\n");
+                                             atomic_notifier_chain_register(&panic_notifier_list,
+                                                                                                    &paniced);
+                                             register_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
+                             }
+
+                             list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);
               } else {
                               drm_fb_helper_set_par(info);
               }
-              /* Switch back to kernel console on panic */
-              /* multi card linked list maybe */
-              if (list_empty(&kernel_fb_helper_list)) {
-                              printk(KERN_INFO "drm: registered panic notifier\n");
-                              atomic_notifier_chain_register(&panic_notifier_list,
-                                                                                     &paniced);
-                              register_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
-              }
-              if (new_fb)
-                              list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);
-
               return 0;
}
EXPORT_SYMBOL(drm_fb_helper_single_fb_probe);
--
1.7.5.4

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