fbcon: Move console_lock for register/unlink/unregister

Ideally console_lock becomes an implementation detail of fbcon.c and
doesn't show up anywhere in fbmem.c. We're still pretty far from that,
but at least the register/unregister code is there now.

With this the do_fb_ioctl() handler is the only code in fbmem.c still
calling console_lock().
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Du Cheng <ducheng2@gmail.com>
Cc: Claudio Suarez <cssk@net-c.es>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Zheyu Ma <zheyuma97@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Link: https://patchwork.freedesktop.org/patch/msgid/20220405210335.3434130-15-daniel.vetter@ffwll.ch

drivers/video/fbdev/core/fbcon.c

@@ -2756,10 +2756,12 @@ void fbcon_fb_unbind(struct fb_info *info)
 	int i, new_idx = -1;
 	int idx = info->node;
 
-	WARN_CONSOLE_UNLOCKED();
+	console_lock();
 
-	if (!fbcon_has_console_bind)
+	if (!fbcon_has_console_bind) {
+		console_unlock();
 		return;
+	}
 
 	for (i = first_fb_vc; i <= last_fb_vc; i++) {
 		if (con2fb_map[i] != idx &&
@@ -2794,6 +2796,8 @@ void fbcon_fb_unbind(struct fb_info *info)
 		}
 		fbcon_unbind();
 	}
+
+	console_unlock();
 }
 
 /* called with console_lock held */
@@ -2801,10 +2805,12 @@ void fbcon_fb_unregistered(struct fb_info *info)
 {
 	int i, idx;
 
-	WARN_CONSOLE_UNLOCKED();
+	console_lock();
 
-	if (deferred_takeover)
+	if (deferred_takeover) {
+		console_unlock();
 		return;
+	}
 
 	idx = info->node;
 	for (i = first_fb_vc; i <= last_fb_vc; i++) {
@@ -2833,6 +2839,7 @@ void fbcon_fb_unregistered(struct fb_info *info)
 
 	if (!num_registered_fb)
 		do_unregister_con_driver(&fb_con);
+	console_unlock();
 }
 
 void fbcon_remap_all(struct fb_info *info)
@@ -2890,19 +2897,27 @@ static inline void fbcon_select_primary(struct fb_info *info)
 }
 #endif /* CONFIG_FRAMEBUFFER_DETECT_PRIMARY */
 
+static bool lockless_register_fb;
+module_param_named_unsafe(lockless_register_fb, lockless_register_fb, bool, 0400);
+MODULE_PARM_DESC(lockless_register_fb,
+	"Lockless framebuffer registration for debugging [default=off]");
+
 /* called with console_lock held */
 int fbcon_fb_registered(struct fb_info *info)
 {
 	int ret = 0, i, idx;
 
-	WARN_CONSOLE_UNLOCKED();
+	if (!lockless_register_fb)
+		console_lock();
+	else
+		atomic_inc(&ignore_console_lock_warning);
 
 	idx = info->node;
 	fbcon_select_primary(info);
 
 	if (deferred_takeover) {
 		pr_info("fbcon: Deferring console take-over\n");
-		return 0;
+		goto out;
 	}
 
 	if (info_idx == -1) {
@@ -2922,6 +2937,12 @@ int fbcon_fb_registered(struct fb_info *info)
 		}
 	}
 
+out:
+	if (!lockless_register_fb)
+		console_unlock();
+	else
+		atomic_dec(&ignore_console_lock_warning);
+
 	return ret;
 }
 

drivers/video/fbdev/core/fbmem.c

@@ -1590,14 +1590,9 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a,
 	}
 }
 
-static bool lockless_register_fb;
-module_param_named_unsafe(lockless_register_fb, lockless_register_fb, bool, 0400);
-MODULE_PARM_DESC(lockless_register_fb,
-	"Lockless framebuffer registration for debugging [default=off]");
-
 static int do_register_framebuffer(struct fb_info *fb_info)
 {
-	int i, ret;
+	int i;
 	struct fb_videomode mode;
 
 	if (fb_check_foreignness(fb_info))
@@ -1666,17 +1661,7 @@ static int do_register_framebuffer(struct fb_info *fb_info)
 	}
 #endif
 
-	if (!lockless_register_fb)
-		console_lock();
-	else
-		atomic_inc(&ignore_console_lock_warning);
-	ret = fbcon_fb_registered(fb_info);
-
-	if (!lockless_register_fb)
-		console_unlock();
-	else
-		atomic_dec(&ignore_console_lock_warning);
-	return ret;
+	return fbcon_fb_registered(fb_info);
 }
 
 static void unbind_console(struct fb_info *fb_info)
@@ -1686,9 +1671,7 @@ static void unbind_console(struct fb_info *fb_info)
 	if (WARN_ON(i < 0 || i >= FB_MAX || registered_fb[i] != fb_info))
 		return;
 
-	console_lock();
 	fbcon_fb_unbind(fb_info);
-	console_unlock();
 }
 
 static void unlink_framebuffer(struct fb_info *fb_info)
@@ -1731,9 +1714,7 @@ static void do_unregister_framebuffer(struct fb_info *fb_info)
 		fb_notifier_call_chain(FB_EVENT_FB_UNREGISTERED, &event);
 	}
 #endif
-	console_lock();
 	fbcon_fb_unregistered(fb_info);
-	console_unlock();
 
 	/* this may free fb info */
 	put_fb_info(fb_info);