Hi, On 18/09/13 01:29, John Tapsell wrote: > Do not lock fb_info when calling sending the FB_EVENT_CONBLANK > event. > > In fbmem.c, the semantics are that we acquire the lock_fb_info first, > and then console_lock. However when fbcon.c fbcon_generic_blank() is > called, the console lock could already be held. Locking fb_info can > thus cause a deadlock. So has this happened for you? Or is it just theoretical? > fbmem.c sends the FB_EVENT_BLANK without locking lock_fb_info first, so > this change introduces similar behaviour. I don't think this is true. FB_EVENT_BLANK is sent in fb_blank(). That one is called when FBIOBLANK ioctl is called, and it does lock_fb_info(). I'm not familiar with the console code, but removing a lock makes me feel rather uneasy... But looking at the code, I can also see that console_lock could already be held, so something here definitely looks broken. The only place using FB_EVENT_CONBLANK seems to be backlight, and if I'm not mistaken, it has its own lock, and doesn't depend on the fb_info being locked. Tomi
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