forked from luck/tmp_suning_uos_patched
fb: reorder the lock sequence to fix potential dead lock
Following commits:50e244cc79fb: rework locking to fix lock ordering on takeovere93a9a8687fb: Yet another band-aid for fixing lockdep mess054430e773fbcon: fix locking harder reworked locking to fix related lock ordering on takeover, and introduced console_lock into fbmem, but it seems that the new lock sequence(fb_info->lock ---> console_lock) is against with the one in console_callback(console_lock ---> fb_info->lock), and leads to a potential dead lock as following: [ 601.079000] ====================================================== [ 601.079000] [ INFO: possible circular locking dependency detected ] [ 601.079000] 3.11.0 #189 Not tainted [ 601.079000] ------------------------------------------------------- [ 601.079000] kworker/0:3/619 is trying to acquire lock: [ 601.079000] (&fb_info->lock){+.+.+.}, at: [<ffffffff81397566>] lock_fb_info+0x26/0x60 [ 601.079000] but task is already holding lock: [ 601.079000] (console_lock){+.+.+.}, at: [<ffffffff8141aae3>] console_callback+0x13/0x160 [ 601.079000] which lock already depends on the new lock. [ 601.079000] the existing dependency chain (in reverse order) is: [ 601.079000] -> #1 (console_lock){+.+.+.}: [ 601.079000] [<ffffffff810dc971>] lock_acquire+0xa1/0x140 [ 601.079000] [<ffffffff810c6267>] console_lock+0x77/0x80 [ 601.079000] [<ffffffff81399448>] register_framebuffer+0x1d8/0x320 [ 601.079000] [<ffffffff81cfb4c8>] efifb_probe+0x408/0x48f [ 601.079000] [<ffffffff8144a963>] platform_drv_probe+0x43/0x80 [ 601.079000] [<ffffffff8144853b>] driver_probe_device+0x8b/0x390 [ 601.079000] [<ffffffff814488eb>] __driver_attach+0xab/0xb0 [ 601.079000] [<ffffffff814463bd>] bus_for_each_dev+0x5d/0xa0 [ 601.079000] [<ffffffff81447e6e>] driver_attach+0x1e/0x20 [ 601.079000] [<ffffffff81447a07>] bus_add_driver+0x117/0x290 [ 601.079000] [<ffffffff81448fea>] driver_register+0x7a/0x170 [ 601.079000] [<ffffffff8144a10a>] __platform_driver_register+0x4a/0x50 [ 601.079000] [<ffffffff8144a12d>] platform_driver_probe+0x1d/0xb0 [ 601.079000] [<ffffffff81cfb0a1>] efifb_init+0x273/0x292 [ 601.079000] [<ffffffff81002132>] do_one_initcall+0x102/0x1c0 [ 601.079000] [<ffffffff81cb80a6>] kernel_init_freeable+0x15d/0x1ef [ 601.079000] [<ffffffff8166d2de>] kernel_init+0xe/0xf0 [ 601.079000] [<ffffffff816914ec>] ret_from_fork+0x7c/0xb0 [ 601.079000] -> #0 (&fb_info->lock){+.+.+.}: [ 601.079000] [<ffffffff810dc1d8>] __lock_acquire+0x1e18/0x1f10 [ 601.079000] [<ffffffff810dc971>] lock_acquire+0xa1/0x140 [ 601.079000] [<ffffffff816835ca>] mutex_lock_nested+0x7a/0x3b0 [ 601.079000] [<ffffffff81397566>] lock_fb_info+0x26/0x60 [ 601.079000] [<ffffffff813a4aeb>] fbcon_blank+0x29b/0x2e0 [ 601.079000] [<ffffffff81418658>] do_blank_screen+0x1d8/0x280 [ 601.079000] [<ffffffff8141ab34>] console_callback+0x64/0x160 [ 601.079000] [<ffffffff8108d855>] process_one_work+0x1f5/0x540 [ 601.079000] [<ffffffff8108e04c>] worker_thread+0x11c/0x370 [ 601.079000] [<ffffffff81095fbd>] kthread+0xed/0x100 [ 601.079000] [<ffffffff816914ec>] ret_from_fork+0x7c/0xb0 [ 601.079000] other info that might help us debug this: [ 601.079000] Possible unsafe locking scenario: [ 601.079000] CPU0 CPU1 [ 601.079000] ---- ---- [ 601.079000] lock(console_lock); [ 601.079000] lock(&fb_info->lock); [ 601.079000] lock(console_lock); [ 601.079000] lock(&fb_info->lock); [ 601.079000] *** DEADLOCK *** so we reorder the lock sequence the same as it in console_callback() to avoid this issue. And following Tomi's suggestion, fix these similar issues all in fb subsystem. Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
This commit is contained in:
Gu Zheng
Tomi Valkeinen
parent
deccd24f90
commit
3a41c5dbe8
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@ -1108,14 +1108,16 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
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case FBIOPUT_VSCREENINFO:
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if (copy_from_user(&var, argp, sizeof(var)))
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return -EFAULT;
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if (!lock_fb_info(info))
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return -ENODEV;
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console_lock();
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if (!lock_fb_info(info)) {
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console_unlock();
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return -ENODEV;
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}
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info->flags |= FBINFO_MISC_USEREVENT;
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ret = fb_set_var(info, &var);
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info->flags &= ~FBINFO_MISC_USEREVENT;
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console_unlock();
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unlock_fb_info(info);
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console_unlock();
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if (!ret && copy_to_user(argp, &var, sizeof(var)))
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ret = -EFAULT;
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break;
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@ -1144,12 +1146,14 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
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case FBIOPAN_DISPLAY:
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if (copy_from_user(&var, argp, sizeof(var)))
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return -EFAULT;
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if (!lock_fb_info(info))
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return -ENODEV;
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console_lock();
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if (!lock_fb_info(info)) {
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console_unlock();
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return -ENODEV;
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}
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ret = fb_pan_display(info, &var);
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console_unlock();
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unlock_fb_info(info);
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console_unlock();
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if (ret == 0 && copy_to_user(argp, &var, sizeof(var)))
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return -EFAULT;
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break;
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@ -1184,23 +1188,27 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
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break;
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}
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event.data = &con2fb;
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if (!lock_fb_info(info))
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return -ENODEV;
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console_lock();
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if (!lock_fb_info(info)) {
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console_unlock();
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return -ENODEV;
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}
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event.info = info;
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ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event);
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console_unlock();
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unlock_fb_info(info);
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console_unlock();
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break;
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case FBIOBLANK:
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if (!lock_fb_info(info))
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return -ENODEV;
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console_lock();
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if (!lock_fb_info(info)) {
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console_unlock();
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return -ENODEV;
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}
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info->flags |= FBINFO_MISC_USEREVENT;
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ret = fb_blank(info, arg);
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info->flags &= ~FBINFO_MISC_USEREVENT;
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console_unlock();
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unlock_fb_info(info);
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console_unlock();
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break;
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default:
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if (!lock_fb_info(info))
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@ -1660,12 +1668,15 @@ static int do_register_framebuffer(struct fb_info *fb_info)
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registered_fb[i] = fb_info;
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event.info = fb_info;
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if (!lock_fb_info(fb_info))
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return -ENODEV;
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console_lock();
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if (!lock_fb_info(fb_info)) {
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console_unlock();
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return -ENODEV;
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}
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fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
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console_unlock();
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unlock_fb_info(fb_info);
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console_unlock();
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return 0;
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}
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@ -1678,13 +1689,16 @@ static int do_unregister_framebuffer(struct fb_info *fb_info)
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if (i < 0 || i >= FB_MAX || registered_fb[i] != fb_info)
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return -EINVAL;
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if (!lock_fb_info(fb_info))
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return -ENODEV;
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console_lock();
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if (!lock_fb_info(fb_info)) {
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console_unlock();
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return -ENODEV;
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}
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event.info = fb_info;
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ret = fb_notifier_call_chain(FB_EVENT_FB_UNBIND, &event);
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console_unlock();
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unlock_fb_info(fb_info);
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console_unlock();
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if (ret)
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return -EINVAL;
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@ -177,9 +177,12 @@ static ssize_t store_modes(struct device *device,
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if (i * sizeof(struct fb_videomode) != count)
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return -EINVAL;
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if (!lock_fb_info(fb_info))
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return -ENODEV;
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console_lock();
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if (!lock_fb_info(fb_info)) {
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console_unlock();
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return -ENODEV;
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}
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list_splice(&fb_info->modelist, &old_list);
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fb_videomode_to_modelist((const struct fb_videomode *)buf, i,
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&fb_info->modelist);
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@ -189,8 +192,8 @@ static ssize_t store_modes(struct device *device,
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} else
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fb_destroy_modelist(&old_list);
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console_unlock();
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unlock_fb_info(fb_info);
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console_unlock();
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return 0;
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}
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@ -404,12 +407,16 @@ static ssize_t store_fbstate(struct device *device,
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state = simple_strtoul(buf, &last, 0);
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if (!lock_fb_info(fb_info))
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return -ENODEV;
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console_lock();
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if (!lock_fb_info(fb_info)) {
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console_unlock();
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return -ENODEV;
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}
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fb_set_suspend(fb_info, (int)state);
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console_unlock();
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unlock_fb_info(fb_info);
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console_unlock();
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return count;
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}
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@ -574,8 +574,9 @@ static int sh_mobile_lcdc_display_notify(struct sh_mobile_lcdc_chan *ch,
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switch (event) {
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case SH_MOBILE_LCDC_EVENT_DISPLAY_CONNECT:
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/* HDMI plug in */
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console_lock();
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if (lock_fb_info(info)) {
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console_lock();
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ch->display.width = monspec->max_x * 10;
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ch->display.height = monspec->max_y * 10;
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@ -594,19 +595,20 @@ static int sh_mobile_lcdc_display_notify(struct sh_mobile_lcdc_chan *ch,
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fb_set_suspend(info, 0);
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}
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console_unlock();
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unlock_fb_info(info);
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}
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console_unlock();
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break;
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case SH_MOBILE_LCDC_EVENT_DISPLAY_DISCONNECT:
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/* HDMI disconnect */
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console_lock();
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if (lock_fb_info(info)) {
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console_lock();
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fb_set_suspend(info, 1);
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console_unlock();
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unlock_fb_info(info);
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}
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console_unlock();
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break;
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case SH_MOBILE_LCDC_EVENT_DISPLAY_MODE:
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