linux-kernel - Re: [BUG] at drivers/char/vt.c:3332 do_blank

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Date:	Thu, 22 Feb 2007 07:43:41 +0800
From:	"Antonino A. Daplas" <adaplas@...il.com>
To:	caglar@...dus.org.tr
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Pavel Machek <pavel@....cz>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] at drivers/char/vt.c:3332 do_blank_screen() on resume

On Thu, 2007-02-15 at 13:00 +0200, S.Çağlar Onur wrote: 
> 15 Şub 2007 Per tarihinde, Andrew Morton şunları yazmıştı: 
> > On Thu, 15 Feb 2007 11:40:32 +0100 Pavel Machek <pavel@....cz> wrote:
> > > Contact fbcon people...
> >
> > There aren't any, basically.  Since Tony disappeared James has been helping
> > out but doesn't have a lot of time.  So we're pretty much on our own with
> > problems in this area.
> 
> I already sent same mail to  
> linux-fbdev-devel mailing lists at sf.net with hope :)
> 
> Cheers

Interesting... It does look like this was triggered by calling
do_blank_screen() without taking the console semaphore, but
console_callback() should have taken that.

Second point is that vesafb does not have any blanking functionality,
thus it should not trigger fbcon_event_notify().  My guess is you are
using an out-of-tree vesafb?

BUG: at drivers/char/vt.c:3332 do_blank_screen() 
 [<c02881f7>] do_blank_screen+0x4e/0x218
 [<c02977fa>] fbcon_event_notify+0x8f1/0xa1e
 [<c027b2b0>] extract_buf+0xac/0xe1
 [<c0102002>] __switch_to+0xeb/0x15d
 [<c034bbe5>] __sched_text_start+0x865/0x929
 [<c029a50d>] bit_cursor+0x4c8/0x50b
 [<c034bd67>] wait_for_completion+0x79/0xaf
 [<c011cbe2>] default_wake_function+0x0/0xc
 [<c034ece2>] notifier_call_chain+0x19/0x32
 [<c012d1c6>] blocking_notifier_call_chain+0x23/0x33
 [<c028db54>] fb_blank+0x4a/0x53
 [<c0299028>] fbcon_blank+0xf4/0x1e3
 [<c0294f33>] fbcon_cursor+0x21c/0x250
 [<c029a045>] bit_cursor+0x0/0x50b
 [<c0129e90>] lock_timer_base+0x15/0x2f
 [<c0129eee>] try_to_del_timer_sync+0x44/0x4a
 [<c0298f34>] fbcon_blank+0x0/0x1e3
 [<c028835a>] do_blank_screen+0x1b1/0x218
 [<c028abdd>] console_callback+0xaf/0xbf
 [<c012fa59>] run_workqueue+0x85/0x135
 [<c028ab2e>] console_callback+0x0/0xbf
 [<c01302f0>] worker_thread+0x10a/0x136
 [<c011cbe2>] default_wake_function+0x0/0xc
 [<c01301e6>] worker_thread+0x0/0x136
 [<c0132982>] kthread+0xb2/0xdc
 [<c01328d0>] kthread+0x0/0xdc
 [<c0103a8f>] kernel_thread_helper+0x7/0x10

As for the last tracing, it looks to be valid bug to me.
complete_change_console() should be called with the console sem
taken. I'll look into this.

BUG: at drivers/char/vt.c:3486 set_palette()
 [<c0287538>] set_palette+0x41/0x59
 [<c028886f>] redraw_screen+0x110/0x17e
 [<c0282394>] complete_change_console+0x2a/0xba
 [<c028ab73>] console_callback+0x45/0xbf
 [<c012fa59>] run_workqueue+0x85/0x135
 [<c028ab2e>] console_callback+0x0/0xbf
 [<c01302f0>] worker_thread+0x10a/0x136
 [<c011cbe2>] default_wake_function+0x0/0xc
 [<c01301e6>] worker_thread+0x0/0x136
 [<c0132982>] kthread+0xb2/0xdc
 [<c01328d0>] kthread+0x0/0xdc
 [<c0103a8f>] kernel_thread_helper+0x7/0x10

Tony
 

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