From 4fda5464ad9ef6c4ca21d0a2b94e8db6ba795944 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Tue, 5 Nov 2013 16:54:50 +1100 Subject: [PATCH] drm/fb-helper: don't sleep for screen unblank when an oops is in progress Otherwise the system will burn even brighter and worse, leave the user wondering what's going on exactly. Since we already have a panic handler which will (try) to restore the entire fbdev console mode, we can just bail out. Inspired by a patch from Konstantin Khlebnikov. The callchain leading to this, cut&pasted from Konstantin's original patch: callstack: panic() bust_spinlocks(1) unblank_screen() vc->vc_sw->con_blank() fbcon_blank() fb_blank() info->fbops->fb_blank() drm_fb_helper_blank() drm_fb_helper_dpms() drm_modeset_lock_all() mutex_lock(&dev->mode_config.mutex) Note that the entire locking in the fb helper around panic/sysrq and kdbg is ... non-existant. So we have a decent change of blowing up everything. But since reworking this ties in with funny concepts like the fbdev notifier chain or the impressive things which happen around console_lock while oopsing, I'll leave that as an exercise for braver souls than me. Signed-off-by: Daniel Vetter Cc: Konstantin Khlebnikov Cc: Dave Airlie Reviewed-by: Rob Clark Signed-off-by: Andrew Morton --- drivers/gpu/drm/drm_fb_helper.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 3d13ca6e257f..f6f6cc7fc133 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -407,6 +407,14 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode) struct drm_connector *connector; int i, j; + /* + * fbdev->blank can be called from irq context in case of a panic. + * Since we already have our own special panic handler which will + * restore the fbdev console mode completely, just bail out early. + */ + if (oops_in_progress) + return; + /* * fbdev->blank can be called from irq context in case of a panic. * Since we already have our own special panic handler which will -- 2.39.5