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authorDaniel Vetter <daniel.vetter@ffwll.ch>2013-09-13 17:49:57 -0400
committerDave Airlie <airlied@redhat.com>2013-09-18 21:54:34 -0400
commit928c2f0c006bf7f381f58af2b2786d2a858ae311 (patch)
treeac885b03ae981679ddc48ed6d763c6080e8ef62a
parentbcf73a10837e9695f5ca7e3e65bf6ce850692d41 (diff)
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 <daniel.vetter@ffwll.ch> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Dave Airlie <airlied@gmail.com> Reviewed-by: Rob Clark <robdclark@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dave Airlie <airlied@redhat.com>
-rw-r--r--drivers/gpu/drm/drm_fb_helper.c8
1 files changed, 8 insertions, 0 deletions
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
@@ -416,6 +416,14 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
416 return; 416 return;
417 417
418 /* 418 /*
419 * fbdev->blank can be called from irq context in case of a panic.
420 * Since we already have our own special panic handler which will
421 * restore the fbdev console mode completely, just bail out early.
422 */
423 if (oops_in_progress)
424 return;
425
426 /*
419 * For each CRTC in this fb, turn the connectors on/off. 427 * For each CRTC in this fb, turn the connectors on/off.
420 */ 428 */
421 drm_modeset_lock_all(dev); 429 drm_modeset_lock_all(dev);