Commit 928c2f0c authored by Daniel Vetter's avatar Daniel Vetter Committed by Dave Airlie

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: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Dave Airlie <airlied@gmail.com>
Reviewed-by: default avatarRob Clark <robdclark@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent bcf73a10
...@@ -407,6 +407,14 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode) ...@@ -407,6 +407,14 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
struct drm_connector *connector; struct drm_connector *connector;
int i, j; 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. * fbdev->blank can be called from irq context in case of a panic.
* Since we already have our own special panic handler which will * Since we already have our own special panic handler which will
......
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