fbcon: Extract fbcon_open/release helpers

There's two minor behaviour changes in here:
- in error paths we now consistently call fb_ops->fb_release
- fb_release really can't fail (fbmem.c ignores it too) and there's no
  reasonable cleanup we can do anyway.

Note that everything in fbcon.c is protected by the big console_lock()
lock (especially all the global variables), so the minor changes in
ordering of setup/cleanup do not matter.

v2: Explain a bit better why this is all correct (Sam)

Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
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: Du Cheng <ducheng2@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220405210335.3434130-10-daniel.vetter@ffwll.ch

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 81860ca..d50154b 100644 (file)
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -682,19 +682,37 @@ static int fbcon_invalid_charcount(struct fb_info *info, unsigned charcount)
 
 #endif /* CONFIG_MISC_TILEBLITTING */
 
+static int fbcon_open(struct fb_info *info)
+{
+       if (!try_module_get(info->fbops->owner))
+               return -ENODEV;
+
+       if (info->fbops->fb_open &&
+           info->fbops->fb_open(info, 0)) {
+               module_put(info->fbops->owner);
+               return -ENODEV;
+       }
+
+       return 0;
+}
+
+static void fbcon_release(struct fb_info *info)
+{
+       if (info->fbops->fb_release)
+               info->fbops->fb_release(info, 0);
+
+       module_put(info->fbops->owner);
+}
 
 static int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info,
                                  int unit, int oldidx)
 {
        struct fbcon_ops *ops = NULL;
-       int err = 0;
-
-       if (!try_module_get(info->fbops->owner))
-               err = -ENODEV;
+       int err;
 
-       if (!err && info->fbops->fb_open &&
-           info->fbops->fb_open(info, 0))
-               err = -ENODEV;
+       err = fbcon_open(info);
+       if (err)
+               return err;
 
        if (!err) {
                ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL);
@@ -715,7 +733,7 @@ static int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info,
 
        if (err) {
                con2fb_map[unit] = oldidx;
-               module_put(info->fbops->owner);
+               fbcon_release(info);
        }
 
        return err;
@@ -726,45 +744,34 @@ static int con2fb_release_oldinfo(struct vc_data *vc, struct fb_info *oldinfo,
                                  int oldidx, int found)
 {
        struct fbcon_ops *ops = oldinfo->fbcon_par;
-       int err = 0, ret;
+       int ret;
 
-       if (oldinfo->fbops->fb_release &&
-           oldinfo->fbops->fb_release(oldinfo, 0)) {
-               con2fb_map[unit] = oldidx;
-               if (!found && newinfo->fbops->fb_release)
-                       newinfo->fbops->fb_release(newinfo, 0);
-               if (!found)
-                       module_put(newinfo->fbops->owner);
-               err = -ENODEV;
-       }
+       fbcon_release(oldinfo);
 
-       if (!err) {
-               fbcon_del_cursor_work(oldinfo);
-               kfree(ops->cursor_state.mask);
-               kfree(ops->cursor_data);
-               kfree(ops->cursor_src);
-               kfree(ops->fontbuffer);
-               kfree(oldinfo->fbcon_par);
-               oldinfo->fbcon_par = NULL;
-               module_put(oldinfo->fbops->owner);
-               /*
-                 If oldinfo and newinfo are driving the same hardware,
-                 the fb_release() method of oldinfo may attempt to
-                 restore the hardware state.  This will leave the
-                 newinfo in an undefined state. Thus, a call to
-                 fb_set_par() may be needed for the newinfo.
-               */
-               if (newinfo && newinfo->fbops->fb_set_par) {
-                       ret = newinfo->fbops->fb_set_par(newinfo);
+       fbcon_del_cursor_work(oldinfo);
+       kfree(ops->cursor_state.mask);
+       kfree(ops->cursor_data);
+       kfree(ops->cursor_src);
+       kfree(ops->fontbuffer);
+       kfree(oldinfo->fbcon_par);
+       oldinfo->fbcon_par = NULL;
+       /*
+         If oldinfo and newinfo are driving the same hardware,
+         the fb_release() method of oldinfo may attempt to
+         restore the hardware state.  This will leave the
+         newinfo in an undefined state. Thus, a call to
+         fb_set_par() may be needed for the newinfo.
+       */
+       if (newinfo && newinfo->fbops->fb_set_par) {
+               ret = newinfo->fbops->fb_set_par(newinfo);
 
-                       if (ret)
-                               printk(KERN_ERR "con2fb_release_oldinfo: "
-                                       "detected unhandled fb_set_par error, "
-                                       "error code %d\n", ret);
-               }
+               if (ret)
+                       printk(KERN_ERR "con2fb_release_oldinfo: "
+                               "detected unhandled fb_set_par error, "
+                               "error code %d\n", ret);
        }
 
-       return err;
+       return 0;
 }
 
 static void con2fb_init_display(struct vc_data *vc, struct fb_info *info,
@@ -919,7 +926,6 @@ static const char *fbcon_startup(void)
        struct fbcon_display *p = &fb_display[fg_console];
        struct vc_data *vc = vc_cons[fg_console].d;
        const struct font_desc *font = NULL;
-       struct module *owner;
        struct fb_info *info = NULL;
        struct fbcon_ops *ops;
        int rows, cols;
@@ -938,17 +944,12 @@ static const char *fbcon_startup(void)
        if (!info)
                return NULL;
        
-       owner = info->fbops->owner;
-       if (!try_module_get(owner))
+       if (fbcon_open(info))
                return NULL;
-       if (info->fbops->fb_open && info->fbops->fb_open(info, 0)) {
-               module_put(owner);
-               return NULL;
-       }
 
        ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL);
        if (!ops) {
-               module_put(owner);
+               fbcon_release(info);
                return NULL;
        }
 
@@ -3314,10 +3315,6 @@ static void fbcon_exit(void)
                }
 
                if (mapped) {
-                       if (info->fbops->fb_release)
-                               info->fbops->fb_release(info, 0);
-                       module_put(info->fbops->owner);
-
                        if (info->fbcon_par) {
                                struct fbcon_ops *ops = info->fbcon_par;
 
@@ -3327,6 +3324,8 @@ static void fbcon_exit(void)
                                kfree(info->fbcon_par);
                                info->fbcon_par = NULL;
                        }
+
+                       fbcon_release(info);
                }
        }
 }