linux-stable.git/drivers/video/console/fbcon.c, branch linux-3.5.y

fbcon: fix race condition between console lock and cursor timer (v1.1)

2012-10-02T17:39:40+00:00

commit d8636a2717bb3da2a7ce2154bf08de90bb8c87b0 upstream.

So we've had a fair few reports of fbcon handover breakage between
efi/vesafb and i915 surface recently, so I dedicated a couple of
days to finding the problem.

Essentially the last thing we saw was the conflicting framebuffer
message and that was all.

So after much tracing with direct netconsole writes (printks
under console_lock not so useful), I think I found the race.

Thread A (driver load)    Thread B (timer thread)
  unbind_con_driver ->              |
  bind_con_driver ->                |
  vc->vc_sw->con_deinit ->          |
  fbcon_deinit ->                   |
  console_lock()                    |
      |                             |
      |                       fbcon_flashcursor timer fires
      |                       console_lock() <- blocked for A
      |
      |
fbcon_del_cursor_timer ->
  del_timer_sync
  (BOOM)

Of course because all of this is under the console lock,
we never see anything, also since we also just unbound the active
console guess what we never see anything.

Hopefully this fixes the problem for anyone seeing vesafb->kms
driver handoff.

v1.1: add comment suggestion from Alan.

Signed-off-by: Dave Airlie 
Acked-by: Alan Cox 
Tested-by: Josh Boyer 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Remove all #inclusions of asm/system.h

2012-03-28T17:30:03+00:00

Remove all #inclusions of asm/system.h preparatory to splitting and killing
it.  Performed with the following command:

perl -p -i -e 's!^#\s*include\s*.*\n!!' `grep -Irl '^#\s*include\s*' *`

Signed-off-by: David Howells

fbcon: Remove unused 'display *p' variable from fb_flashcursor()

2011-03-31T04:48:54+00:00

Signed-off-by: Sergey Senozhatsky 
Signed-off-by: Paul Mundt

fbcon: fix situation where fbcon gets deinitialised and can't reinit.

2011-03-22T08:22:19+00:00

Situation as follow:
2 GPUs + vesafb + kms.

GPU 1 is primary, vesafb binds to it as fb0
radeon loads
GPU 0 loads as fb1
GPU 1 loads, vesafb gets kicked off which causes fb0 to unbind
console, which causes the dummy console to rebind.

this means fbcon_deinit gets called, which calls fbcon_exit
since the console isn't bound anymore and we set fbcon_has_exited.

GPU 1 creates a new fb0 which is primary and we want to be console.
fbcon_fb_registered gets called sets the primary up and calls set_con2fb_map,
however as fbcon_has_exited is set nothing further ever happens.

This patch bypasses the fbcon_has_exited and checks if the console is unbound,
if its unbound it calls the fbcon_takeover which calls the vt layer to
call the fbcon_startup method and everthing works.

Signed-off-by: Dave Airlie 
Signed-off-by: Paul Mundt

console: rename acquire/release_console_sem() to console_lock/unlock()

2011-01-26T00:50:06+00:00

The -rt patches change the console_semaphore to console_mutex.  As a
result, a quite large chunk of the patches changes all
acquire/release_console_sem() to acquire/release_console_mutex()

This commit makes things use more neutral function names which dont make
implications about the underlying lock.

The only real change is the return value of console_trylock which is
inverted from try_acquire_console_sem()

This patch also paves the way to switching console_sem from a semaphore to
a mutex.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: make console_trylock return 1 on success, per Geert]
Signed-off-by: Torben Hohn 
Cc: Thomas Gleixner 
Cc: Greg KH 
Cc: Ingo Molnar 
Cc: Geert Uytterhoeven 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fbcon: fix lockdep warning from fbcon_deinit()

2010-09-23T00:22:39+00:00

Fix the lockdep warning:

[   13.657164] INFO: trying to register non-static key.
[   13.657169] the code is fine but needs lockdep annotation.
[   13.657171] turning off the locking correctness validator.
[   13.657177] Pid: 622, comm: modprobe Not tainted 2.6.36-rc3c #8
[   13.657180] Call Trace:
[   13.657194]  [] ? printk+0x18/0x20
[   13.657202]  [] register_lock_class+0x336/0x350
[   13.657208]  [] __lock_acquire+0x449/0x1180
[   13.657215]  [] lock_acquire+0x67/0x80
[   13.657222]  [] ? __cancel_work_timer+0x51/0x230
[   13.657227]  [] __cancel_work_timer+0x83/0x230
[   13.657231]  [] ? __cancel_work_timer+0x51/0x230
[   13.657236]  [] ? mark_held_locks+0x62/0x80
[   13.657243]  [] ? kfree+0x7f/0xe0
[   13.657248]  [] ? trace_hardirqs_on_caller+0x11c/0x160
[   13.657253]  [] ? trace_hardirqs_on+0xb/0x10
[   13.657259]  [] ? fbcon_deinit+0x16d/0x1e0
[   13.657263]  [] ? fbcon_deinit+0x16d/0x1e0
[   13.657268]  [] cancel_work_sync+0xa/0x10
[   13.657272]  [] fbcon_deinit+0xe4/0x1e0
...

The warning is caused by trying to cancel an uninitialized work from
fbcon_exit().  Fix it by adding a check for queue.func, similarly to other
places in this code.

Signed-off-by: Jarek Poplawski 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fbcon: uninline large static function get_color()

2010-08-11T15:59:09+00:00

This function's body is good two screenfuls and it has six callsites.  No
apparent reason why it is marked inline.

Signed-off-by: Denys Vlasenko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vt/console: try harder to print output when panicing

2010-08-10T20:47:40+00:00

Jesse's initial patch commit said:

"At panic time (i.e.  when oops_in_progress is set) we should try a bit
harder to update the screen and make sure output gets to the VT, since
some drivers are capable of flipping back to it.

So make sure we try to unblank and update the display if called from a
panic context."

I've enhanced this to add a flag to the vc that console layer can set to
indicate they want this behaviour to occur.  This also adds support to
fbcon for that flag and adds an fb flag for drivers to indicate they want
to use the support.  It enables this for KMS drivers.

Signed-off-by: Dave Airlie 
Signed-off-by: Jesse Barnes 
Acked-by: James Simmons 
Cc: Alan Cox 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

fb: add hooks to handle KDB enter/exit

2010-08-05T14:22:31+00:00

Add fb ops to handle enter/exit of the kernel debugger.  If present, the
fb core will register them with KGDB and they'll be called when the
debugger is entered and exited.  The new functions are responsible for
switching to an appropriate debug framebuffer and restoring the
interrupted state at exit time.

Signed-off-by: Jesse Barnes 
Signed-off-by: Jason Wessel

vga_switcheroo: initial implementation (v15)

2010-03-01T06:20:37+00:00

Many new laptops now come with 2 gpus, one to be used for low power
modes and one for gaming/on-ac applications. These GPUs are typically
wired to the laptop panel and VGA ports via a multiplexer unit which
is controlled via ACPI methods.

4 combinations of systems typically exist - with 2 ACPI methods.
Intel/ATI - Lenovo W500/T500 - use ATPX ACPI method
ATI/ATI - some ASUS - use ATPX ACPI Method
Intel/Nvidia - - use _DSM ACPI method
Nvidia/Nvidia -  - use _DSM ACPI method.

TODO:
This patch adds support for the ATPX method and initial bits
for the _DSM methods that need to written by someone with
access to the hardware.
Add a proper non-debugfs interface - need to get some proper
testing first.

v2: add power up/down support for both devices
on W500 puts i915/radeon into D3 and cuts power to radeon.

v3: redo probing methods, no DMI list, drm devices call to
register with switcheroo, it tries to find an ATPX method on
any device and once there is two devices + ATPX it inits the
switcher.

v4: ATPX msg handling using buffers - should work on more machines

v5: rearchitect after more mjg59 discussion - move ATPX handling to
    radeon driver.

v6: add file headers + initial nouveau bits (to be filled out).

v7: merge delayed switcher code.

v8: avoid suspend/resume of gpu that is off

v9: rearchitect - mjg59 is always right. - move all ATPX code to
radeon, should allow simpler DSM also proper ATRM handling

v10: add ATRM support for radeon BIOS, add mutex to lock vgasr_priv

v11: fix bug in resuming Intel for 2nd time.

v12: start fixing up nvidia code blindly.

v13: blindly guess at finishing nvidia code

v14: remove radeon audio hacks - fix up intel resume more like upstream

v15: clean up printks + remove unnecessary igd/dis pointers

mount debugfs

/sys/kernel/debug/vgaswitcheroo/switch - should exist if ATPX detected
 + 2 cards.

DIS - immediate change to discrete
IGD - immediate change to IGD
DDIS - delayed change to discrete
DIGD - delayed change to IGD
ON - turn on not in use
OFF - turn off not in use

Tested on W500 (Intel/ATI) and T500 (Intel/ATI)

Signed-off-by: Dave Airlie