fbcon: fix locking harder

Okay so Alan's patch handled the case where there was no registered fbcon,
however the other path entered in set_con2fb_map pit.

In there we called fbcon_takeover, but we also took the console lock in a couple
of places. So push the console lock out to the callers of set_con2fb_map,

this means fbmem and switcheroo needed to take the lock around the fb notifier
entry points that lead to this.

This should fix the efifb regression seen by Maarten.

Tested-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Tested-by: Lu Hua <huax.lu@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

3 files changed, 13 insertions, 3 deletions

diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index fa60add0ff63..cf787e1d9322 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -25,6 +25,7 @@
 #include <linux/fb.h>
 
 #include <linux/pci.h>
+#include <linux/console.h>
 #include <linux/vga_switcheroo.h>
 
 #include <linux/vgaarb.h>
@@ -337,8 +338,10 @@ static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
 
         if (new_client->fb_info) {
                 struct fb_event event;
+                console_lock();
                 event.info = new_client->fb_info;
                 fb_notifier_call_chain(FB_EVENT_REMAP_ALL_CONSOLE, &event);
+                console_unlock();
         }
 
         ret = vgasr_priv.handler->switchto(new_client->id);
diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 2aef9cac4d18..2e2d959acae6 100644
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -842,6 +842,8 @@ static void con2fb_init_display(struct vc_data *vc, struct fb_info *info,
  *
  *      Maps a virtual console @unit to a frame buffer device
  *      @newidx.
+ *
+ *      This should be called with the console lock held.
  */
 static int set_con2fb_map(int unit, int newidx, int user)
 {
@@ -859,7 +861,7 @@ static int set_con2fb_map(int unit, int newidx, int user)
 
         if (!search_for_mapped_con() || !con_is_bound(&fb_con)) {
                 info_idx = newidx;
-                return fbcon_takeover(0);
+                return do_fbcon_takeover(0);
         }
 
         if (oldidx != -1)
@@ -867,7 +869,6 @@ static int set_con2fb_map(int unit, int newidx, int user)
 
         found = search_fb_in_map(newidx);
 
-        console_lock();
         con2fb_map[unit] = newidx;
         if (!err && !found)
                 err = con2fb_acquire_newinfo(vc, info, unit, oldidx);
@@ -894,7 +895,6 @@ static int set_con2fb_map(int unit, int newidx, int user)
         if (!search_fb_in_map(info_idx))
                 info_idx = newidx;
 
-        console_unlock();
         return err;
 }
 
@@ -3019,6 +3019,7 @@ static inline int fbcon_unbind(void)
 }
 #endif /* CONFIG_VT_HW_CONSOLE_BINDING */
 
+/* called with console_lock held */
 static int fbcon_fb_unbind(int idx)
 {
         int i, new_idx = -1, ret = 0;
@@ -3045,6 +3046,7 @@ static int fbcon_fb_unbind(int idx)
         return ret;
 }
 
+/* called with console_lock held */
 static int fbcon_fb_unregistered(struct fb_info *info)
 {
         int i, idx;
@@ -3082,6 +3084,7 @@ static int fbcon_fb_unregistered(struct fb_info *info)
         return 0;
 }
 
+/* called with console_lock held */
 static void fbcon_remap_all(int idx)
 {
         int i;
@@ -3126,6 +3129,7 @@ static inline void fbcon_select_primary(struct fb_info *info)
 }
 #endif /* CONFIG_FRAMEBUFFER_DETECT_PRIMARY */
 
+/* called with console_lock held */
 static int fbcon_fb_registered(struct fb_info *info)
 {
         int ret = 0, i, idx;
@@ -3278,6 +3282,7 @@ static int fbcon_event_notify(struct notifier_block *self,
                 ret = fbcon_fb_unregistered(info);
                 break;
         case FB_EVENT_SET_CONSOLE_MAP:
+                /* called with console lock held */
                 con2fb = event->data;
                 ret = set_con2fb_map(con2fb->console - 1,
                                      con2fb->framebuffer, 1);
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 070b9a13d892..dc61c12ecf8c 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1177,8 +1177,10 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
                 event.data = &con2fb;
                 if (!lock_fb_info(info))
                         return -ENODEV;
+                console_lock();
                 event.info = info;
                 ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event);
+                console_unlock();
                 unlock_fb_info(info);
                 break;
         case FBIOBLANK: