fbdev: make unregister/unlink functions not fail

Except for driver bugs (which we'll catch with a WARN_ON) this is only
to report failures of the new driver taking over the console. There's
nothing the outgoing driver can do about that, and no one ever
bothered to actually look at these return values. So remove them all.

v2: fixup unregister_framebuffer in savagefb, fbtft, ivtvfb, and neofb
drivers, reported by kbuild.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Cc: Peter Rosin <peda@axentia.se>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: linux-fbdev@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20190528090304.9388-19-daniel.vetter@ffwll.ch

drivers/media/pci/ivtv/ivtvfb.c

@@ -1246,11 +1246,7 @@ static int ivtvfb_callback_cleanup(struct device *dev, void *p)
 	struct osd_info *oi = itv->osd_info;
 
 	if (itv->v4l2_cap & V4L2_CAP_VIDEO_OUTPUT) {
-		if (unregister_framebuffer(&itv->osd_info->ivtvfb_info)) {
-			IVTVFB_WARN("Framebuffer %d is in use, cannot unload\n",
-				       itv->instance);
-			return 0;
-		}
+		unregister_framebuffer(&itv->osd_info->ivtvfb_info);
 		IVTVFB_INFO("Unregister framebuffer %d\n", itv->instance);
 		itv->ivtvfb_restore = NULL;
 		ivtvfb_blank(FB_BLANK_VSYNC_SUSPEND, &oi->ivtvfb_info);

drivers/staging/fbtft/fbtft-core.c

@@ -891,7 +891,9 @@ int fbtft_unregister_framebuffer(struct fb_info *fb_info)
 	if (par->fbtftops.unregister_backlight)
 		par->fbtftops.unregister_backlight(par);
 	fbtft_sysfs_exit(par);
-	return unregister_framebuffer(fb_info);
+	unregister_framebuffer(fb_info);
+
+	return 0;
 }
 EXPORT_SYMBOL(fbtft_unregister_framebuffer);
 

drivers/video/fbdev/core/fbmem.c

@@ -1590,13 +1590,13 @@ static bool fb_do_apertures_overlap(struct apertures_struct *gena,
 	return false;
 }
 
-static int do_unregister_framebuffer(struct fb_info *fb_info);
+static void do_unregister_framebuffer(struct fb_info *fb_info);
 
 #define VGA_FB_PHYS 0xA0000
-static int do_remove_conflicting_framebuffers(struct apertures_struct *a,
-					      const char *name, bool primary)
+static void do_remove_conflicting_framebuffers(struct apertures_struct *a,
+					       const char *name, bool primary)
 {
-	int i, ret;
+	int i;
 
 	/* check all firmware fbs and kick off if the base addr overlaps */
 	for_each_registered_fb(i) {
@@ -1612,13 +1612,9 @@ static int do_remove_conflicting_framebuffers(struct apertures_struct *a,
 
 			printk(KERN_INFO "fb%d: switching to %s from %s\n",
 			       i, name, registered_fb[i]->fix.id);
-			ret = do_unregister_framebuffer(registered_fb[i]);
-			if (ret)
-				return ret;
+			do_unregister_framebuffer(registered_fb[i]);
 		}
 	}
-
-	return 0;
 }
 
 static bool lockless_register_fb;
@@ -1634,11 +1630,9 @@ static int do_register_framebuffer(struct fb_info *fb_info)
 	if (fb_check_foreignness(fb_info))
 		return -ENOSYS;
 
-	ret = do_remove_conflicting_framebuffers(fb_info->apertures,
-						 fb_info->fix.id,
-						 fb_is_primary_device(fb_info));
-	if (ret)
-		return ret;
+	do_remove_conflicting_framebuffers(fb_info->apertures,
+					   fb_info->fix.id,
+					   fb_is_primary_device(fb_info));
 
 	if (num_registered_fb == FB_MAX)
 		return -ENXIO;
@@ -1714,32 +1708,25 @@ static int do_register_framebuffer(struct fb_info *fb_info)
 	return ret;
 }
 
-static int unbind_console(struct fb_info *fb_info)
+static void unbind_console(struct fb_info *fb_info)
 {
 	int i = fb_info->node;
 
-	if (i < 0 || i >= FB_MAX || registered_fb[i] != fb_info)
-		return -EINVAL;
+	if (WARN_ON(i < 0 || i >= FB_MAX || registered_fb[i] != fb_info))
+		return;
 
 	console_lock();
 	lock_fb_info(fb_info);
 	fbcon_fb_unbind(fb_info);
 	unlock_fb_info(fb_info);
 	console_unlock();
-
-	return 0;
 }
 
-static int __unlink_framebuffer(struct fb_info *fb_info);
+static void __unlink_framebuffer(struct fb_info *fb_info);
 
-static int do_unregister_framebuffer(struct fb_info *fb_info)
+static void do_unregister_framebuffer(struct fb_info *fb_info)
 {
-	int ret;
-
-	ret = unbind_console(fb_info);
-
-	if (ret)
-		return -EINVAL;
+	unbind_console(fb_info);
 
 	pm_vt_switch_unregister(fb_info->dev);
 
@@ -1764,36 +1751,27 @@ static int do_unregister_framebuffer(struct fb_info *fb_info)
 
 	/* this may free fb info */
 	put_fb_info(fb_info);
-	return 0;
 }
 
-static int __unlink_framebuffer(struct fb_info *fb_info)
+static void __unlink_framebuffer(struct fb_info *fb_info)
 {
 	int i;
 
 	i = fb_info->node;
-	if (i < 0 || i >= FB_MAX || registered_fb[i] != fb_info)
-		return -EINVAL;
+	if (WARN_ON(i < 0 || i >= FB_MAX || registered_fb[i] != fb_info))
+		return;
 
 	if (fb_info->dev) {
 		device_destroy(fb_class, MKDEV(FB_MAJOR, i));
 		fb_info->dev = NULL;
 	}
-
-	return 0;
 }
 
-int unlink_framebuffer(struct fb_info *fb_info)
+void unlink_framebuffer(struct fb_info *fb_info)
 {
-	int ret;
-
-	ret = __unlink_framebuffer(fb_info);
-	if (ret)
-		return ret;
+	__unlink_framebuffer(fb_info);
 
 	unbind_console(fb_info);
-
-	return 0;
 }
 EXPORT_SYMBOL(unlink_framebuffer);
 
@@ -1810,7 +1788,6 @@ EXPORT_SYMBOL(unlink_framebuffer);
 int remove_conflicting_framebuffers(struct apertures_struct *a,
 				    const char *name, bool primary)
 {
-	int ret;
 	bool do_free = false;
 
 	if (!a) {
@@ -1824,13 +1801,13 @@ int remove_conflicting_framebuffers(struct apertures_struct *a,
 	}
 
 	mutex_lock(&registration_lock);
-	ret = do_remove_conflicting_framebuffers(a, name, primary);
+	do_remove_conflicting_framebuffers(a, name, primary);
 	mutex_unlock(&registration_lock);
 
 	if (do_free)
 		kfree(a);
 
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL(remove_conflicting_framebuffers);
 
@@ -1927,16 +1904,12 @@ EXPORT_SYMBOL(register_framebuffer);
  *      that the driver implements fb_open() and fb_release() to
  *      check that no processes are using the device.
  */
-int
+void
 unregister_framebuffer(struct fb_info *fb_info)
 {
-	int ret;
-
 	mutex_lock(&registration_lock);
-	ret = do_unregister_framebuffer(fb_info);
+	do_unregister_framebuffer(fb_info);
 	mutex_unlock(&registration_lock);
-
-	return ret;
 }
 EXPORT_SYMBOL(unregister_framebuffer);
 

drivers/video/fbdev/neofb.c

@@ -2122,14 +2122,7 @@ static void neofb_remove(struct pci_dev *dev)
 	DBG("neofb_remove");
 
 	if (info) {
-		/*
-		 * If unregister_framebuffer fails, then
-		 * we will be leaving hooks that could cause
-		 * oopsen laying around.
-		 */
-		if (unregister_framebuffer(info))
-			printk(KERN_WARNING
-			       "neofb: danger danger!  Oopsen imminent!\n");
+		unregister_framebuffer(info);
 
 		neo_unmap_video(info);
 		fb_destroy_modedb(info->monspecs.modedb);

drivers/video/fbdev/savage/savagefb_driver.c

@@ -2333,14 +2333,7 @@ static void savagefb_remove(struct pci_dev *dev)
 	DBG("savagefb_remove");
 
 	if (info) {
-		/*
-		 * If unregister_framebuffer fails, then
-		 * we will be leaving hooks that could cause
-		 * oopsen laying around.
-		 */
-		if (unregister_framebuffer(info))
-			printk(KERN_WARNING "savagefb: danger danger! "
-			       "Oopsen imminent!\n");
+		unregister_framebuffer(info);
 
 #ifdef CONFIG_FB_SAVAGE_I2C
 		savagefb_delete_i2c_busses(info);

include/linux/fb.h

@@ -634,8 +634,8 @@ extern ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
 
 /* drivers/video/fbmem.c */
 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 unregister_framebuffer(struct fb_info *fb_info);
+extern void unlink_framebuffer(struct fb_info *fb_info);
 extern int remove_conflicting_pci_framebuffers(struct pci_dev *pdev, int res_id,
 					       const char *name);
 extern int remove_conflicting_framebuffers(struct apertures_struct *a,