fb: sh-mobile: Fix deadlock risk between lock_fb_info() and console_lock()

Following on Herton's patch "fb: avoid possible deadlock caused by
fb_set_suspend" which moves lock_fb_info() out of fb_set_suspend()
to its callers, correct sh-mobile's locking around call to
fb_set_suspend() and the same sort of deaklocks with console_lock()
due to order of taking the lock.

console_lock() must be taken while fb_info is already locked and fb_info
must be locked while calling fb_set_suspend().

Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: stable@kernel.org

diff --git a/drivers/video/sh_mobile_hdmi.c b/drivers/video/sh_mobile_hdmi.c
index 7d54e2c..647ba98 100644 (file)
--- a/drivers/video/sh_mobile_hdmi.c
+++ b/drivers/video/sh_mobile_hdmi.c
@@ -1111,6 +1111,7 @@ static long sh_hdmi_clk_configure(struct sh_hdmi *hdmi, unsigned long hdmi_rate,
 static void sh_hdmi_edid_work_fn(struct work_struct *work)
 {
        struct sh_hdmi *hdmi = container_of(work, struct sh_hdmi, edid_work.work);
+       struct fb_info *info;
        struct sh_mobile_hdmi_info *pdata = hdmi->dev->platform_data;
        struct sh_mobile_lcdc_chan *ch;
        int ret;
@@ -1123,8 +1124,9 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work)
 
        mutex_lock(&hdmi->mutex);
 
+       info = hdmi->info;
+
        if (hdmi->hp_state == HDMI_HOTPLUG_CONNECTED) {
-               struct fb_info *info = hdmi->info;
                unsigned long parent_rate = 0, hdmi_rate;
 
                ret = sh_hdmi_read_edid(hdmi, &hdmi_rate, &parent_rate);
@@ -1148,42 +1150,45 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work)
 
                ch = info->par;
 
-               console_lock();
+               if (lock_fb_info(info)) {
+                       console_lock();
 
-               /* HDMI plug in */
-               if (!sh_hdmi_must_reconfigure(hdmi) &&
-                   info->state == FBINFO_STATE_RUNNING) {
-                       /*
-                        * First activation with the default monitor - just turn
-                        * on, if we run a resume here, the logo disappears
-                        */
-                       if (lock_fb_info(info)) {
+                       /* HDMI plug in */
+                       if (!sh_hdmi_must_reconfigure(hdmi) &&
+                           info->state == FBINFO_STATE_RUNNING) {
+                               /*
+                                * First activation with the default monitor - just turn
+                                * on, if we run a resume here, the logo disappears
+                                */
                                info->var.width = hdmi->var.width;
                                info->var.height = hdmi->var.height;
                                sh_hdmi_display_on(hdmi, info);
-                               unlock_fb_info(info);
+                       } else {
+                               /* New monitor or have to wake up */
+                               fb_set_suspend(info, 0);
                        }
-               } else {
-                       /* New monitor or have to wake up */
-                       fb_set_suspend(info, 0);
-               }
 
-               console_unlock();
+                       console_unlock();
+                       unlock_fb_info(info);
+               }
        } else {
                ret = 0;
-               if (!hdmi->info)
+               if (!info)
                        goto out;
 
                hdmi->monspec.modedb_len = 0;
                fb_destroy_modedb(hdmi->monspec.modedb);
                hdmi->monspec.modedb = NULL;
 
-               console_lock();
+               if (lock_fb_info(info)) {
+                       console_lock();
 
-               /* HDMI disconnect */
-               fb_set_suspend(hdmi->info, 1);
+                       /* HDMI disconnect */
+                       fb_set_suspend(info, 1);
 
-               console_unlock();
+                       console_unlock();
+                       unlock_fb_info(info);
+               }
        }
 
 out: