On Tue, Jan 21, 2014 at 11:34 PM, akpm@linux-foundation.org wrote:

From: Daniel Vetter daniel.vetter@ffwll.ch Subject: 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

We've merged this twic already in 1b1d5397058f06b and 928c2f0c006bf7f381f58 and then had to take out the superflous hunk again in ecc7e6f3bb8ad56764

For some oddball reason git/patch _really_ gets confused here and loves to readd that hunk a few more times (iirc one of my own trees once even ended up with 3 copies ...). No idea what's going on, but we can drop this on here ;-)

Or what exactly was the point of this patch submission, I didn't spot a "dropped from -mm" or similar note, and it doesn't seem to be cc'ed to lists.

Cheers, Daniel