[PATCH 1/2] video/fb: Propagate error code from failing to unregister conflicting fb

[Chris Wilson]

If we fail to remove a conflicting fb driver, we need to abort the
loading of the second driver to avoid likely kernel panics.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Jean-Christophe Plagniol-Villard <plagnioj at jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen at ti.com>
Cc: linux-fbdev at vger.kernel.org
Cc: dri-devel at lists.freedesktop.org
---
 drivers/video/fbmem.c | 31 +++++++++++++++++++++----------
 include/linux/fb.h    |  4 ++--
 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 010d19105ebc..e296967a3abb 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1577,10 +1577,10 @@ static bool fb_do_apertures_overlap(struct 
apertures_struct *gena,
 static int do_unregister_framebuffer(struct fb_info *fb_info);

 #define VGA_FB_PHYS 0xA0000
-static void do_remove_conflicting_framebuffers(struct apertures_struct *a,
-                                    const char *name, bool primary)
+static int do_remove_conflicting_framebuffers(struct apertures_struct *a,
+                                             const char *name, bool primary)
 {
-       int i;
+       int i, ret;

        /* check all firmware fbs and kick off if the base addr overlaps */
        for (i = 0 ; i < FB_MAX; i++) {
@@ -1599,22 +1599,29 @@ static void do_remove_conflicting_framebuffers(struct 
apertures_struct *a,
                        printk(KERN_INFO "fb: conflicting fb hw usage "
                               "%s vs %s - removing generic driver\n",
                               name, registered_fb[i]->fix.id);
-                       do_unregister_framebuffer(registered_fb[i]);
+                       ret = do_unregister_framebuffer(registered_fb[i]);
+                       if (ret)
+                               return ret;
                }
        }
+
+       return 0;
 }

 static int do_register_framebuffer(struct fb_info *fb_info)
 {
-       int i;
+       int i, ret;
        struct fb_event event;
        struct fb_videomode mode;

        if (fb_check_foreignness(fb_info))
                return -ENOSYS;

-       do_remove_conflicting_framebuffers(fb_info->apertures, fb_info->fix.id,
-                                        fb_is_primary_device(fb_info));
+       ret = do_remove_conflicting_framebuffers(fb_info->apertures,
+                                                fb_info->fix.id,
+                                                fb_is_primary_device(fb_info));
+       if (ret)
+               return ret;

        if (num_registered_fb == FB_MAX)
                return -ENXIO;
@@ -1739,12 +1746,16 @@ int unlink_framebuffer(struct fb_info *fb_info)
 }
 EXPORT_SYMBOL(unlink_framebuffer);

-void remove_conflicting_framebuffers(struct apertures_struct *a,
-                                    const char *name, bool primary)
+int remove_conflicting_framebuffers(struct apertures_struct *a,
+                                   const char *name, bool primary)
 {
+       int ret;
+
        mutex_lock(&registration_lock);
-       do_remove_conflicting_framebuffers(a, name, primary);
+       ret = do_remove_conflicting_framebuffers(a, name, primary);
        mutex_unlock(&registration_lock);
+
+       return ret;
 }
 EXPORT_SYMBOL(remove_conflicting_framebuffers);

diff --git a/include/linux/fb.h b/include/linux/fb.h
index 70c4836e4a9f..fe6ac956550e 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -613,8 +613,8 @@ extern ssize_t fb_sys_write(struct fb_info *info, const 
char __user *buf,
 extern int register_framebuffer(struct fb_info *fb_info);
 extern int unregister_framebuffer(struct fb_info *fb_info);
 extern int unlink_framebuffer(struct fb_info *fb_info);
-extern void remove_conflicting_framebuffers(struct apertures_struct *a,
-                               const char *name, bool primary);
+extern int remove_conflicting_framebuffers(struct apertures_struct *a,
+                                          const char *name, bool primary);
 extern int fb_prepare_logo(struct fb_info *fb_info, int rotate);
 extern int fb_show_logo(struct fb_info *fb_info, int rotate);
 extern char* fb_get_buffer_offset(struct fb_info *info, struct fb_pixmap *buf, 
u32 size);
-- 
1.8.5.1