[PATCH] drm: fb helper should avoid sleeping in panic context

2014-12-15 Thread Luck, Tony 
From: Rui Wang 

There are still some places in the fb helper that need to avoid
sleeping in panic context. Here's an example:

[   65.615496] bad: scheduling from the idle thread!
[   65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G   ME  
3.18.0-rc4-7-default+ #20

[   65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS
BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
[   65.641923]  88087f693d80 88087f689878 81566db9 

[   65.650226]  88087f693d80 88087f689898 810871ff 
88046eb3e0d0
[   65.658527]  88087f693d80 88087f6898c8 8107c1fa 
00017f6898b8
[   65.666830] Call Trace:
[   65.669557]  <#MC>  [] dump_stack+0x46/0x58
[   65.675994]  [] dequeue_task_idle+0x2f/0x40
[   65.682412]  [] dequeue_task+0x5a/0x80
[   65.688345]  [] deactivate_task+0x23/0x30
[   65.694569]  [] __schedule+0x580/0x7f0
[   65.700502]  [] schedule_preempt_disabled+0x29/0x70
[   65.707696]  [] __ww_mutex_lock_slowpath+0xb8/0x162
[   65.714891]  [] __ww_mutex_lock+0x53/0x85
[   65.721125]  [] drm_modeset_lock+0x3d/0x110 [drm]
[   65.728132]  [] __drm_modeset_lock_all+0x8a/0x120 [drm]
[   65.735721]  [] drm_modeset_lock_all+0x10/0x30 [drm]
[   65.743015]  [] drm_fb_helper_pan_display+0x2f/0xf0 
[drm_kms_helper]
[   65.751857]  [] fb_pan_display+0xd1/0x1a0
[   65.758081]  [] bit_update_start+0x20/0x50
[   65.764400]  [] fbcon_switch+0x3a2/0x550
[   65.770528]  [] redraw_screen+0x189/0x240
[   65.776750]  [] fbcon_blank+0x20a/0x2d0
[   65.782778]  [] ? erst_writer+0x209/0x330
[   65.789002]  [] ? internal_add_timer+0x63/0x80
[   65.795710]  [] ? mod_timer+0x127/0x1e0
[   65.801740]  [] do_unblank_screen+0xa8/0x1d0
[   65.808255]  [] unblank_screen+0x10/0x20
[   65.814381]  [] bust_spinlocks+0x19/0x40
[   65.820508]  [] panic+0x106/0x1f5
[   65.825955]  [] mce_panic+0x2ac/0x2e0
[   65.831789]  [] ? delay_tsc+0x4a/0x80
[   65.837625]  [] do_machine_check+0xbaf/0xbf0
[   65.844138]  [] ? intel_idle+0xc7/0x150
[   65.850166]  [] machine_check+0x1f/0x30
[   65.856195]  [] ? intel_idle+0xc7/0x150
[   65.86]  <>  [] cpuidle_enter_state+0x55/0x170
[   65.869823]  [] cpuidle_enter+0x17/0x20
[   65.875852]  [] cpu_startup_entry+0x2d8/0x370
[   65.882467]  [] start_secondary+0x159/0x180

There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
purpose. We can leverage that without reinventing anything. This patch
works with the latest kernel.

Reviewed-by: Rob Clark 
Tested-by: Tony Luck 
Signed-off-by: Rui Wang 
---

Dave: I don't see this in any of your trees yet. Bug is really annoying
when testing machine check code because the above stack dumps just repeat
endlessly until I manually hit the reset button

 drivers/gpu/drm/drm_fb_helper.c | 8 ++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 0c0c39bac23d..70dd2f4eb299 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct 
fb_info *info)
int i, j, rc = 0;
int start;

-   drm_modeset_lock_all(dev);
+   if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+   return -EBUSY;
+   }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
@@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
int ret = 0;
int i;

-   drm_modeset_lock_all(dev);
+   if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+   return -EBUSY;
+   }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
-- 
2.1.0

[PATCH] drm: fb helper should avoid sleeping in panic context

2014-12-10 Thread Borislav Petkov 
On Tue, Dec 09, 2014 at 08:05:21PM -0500, Rob Clark wrote:
> oh, whoops.. gmail hiding quoted text..
> 
> yeah, that looks sane,
> 
> Reviewed-by: Rob Clark 
> 
> On Tue, Dec 9, 2014 at 7:55 PM, rui wang  wrote:
> > Hi Rob,
> > Yes it's exactly what I'm doing. Please scroll down and review my patch.
> >
> > Thanks
> > Rui
> >
> > On 12/10/14, Rob Clark  wrote:
> >> perhaps fb helpers could use __drm_modeset_lock_all() w/ trylock=true
> >> in panic context?
> >>
> >> BR,
> >> -R
> >>
> >> On Tue, Dec 9, 2014 at 7:09 PM, rui wang  wrote:
> >>> Hi All,
> >>>
> >>> Any comment ? Or any better idea how this should be fixed?
> >>>
> >>> Regards,
> >>> Rui
> >>>

Dear gmail-ers,

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

Please stop the top-posting or use a mail client which doesn't
facilitate the idiocy.

Thanks.

-- 
Regards/Gruss,
Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

[PATCH] drm: fb helper should avoid sleeping in panic context

2014-12-10 Thread rui wang 
Hi Rob,
Yes it's exactly what I'm doing. Please scroll down and review my patch.

Thanks
Rui

On 12/10/14, Rob Clark  wrote:
> perhaps fb helpers could use __drm_modeset_lock_all() w/ trylock=true
> in panic context?
>
> BR,
> -R
>
> On Tue, Dec 9, 2014 at 7:09 PM, rui wang  wrote:
>> Hi All,
>>
>> Any comment ? Or any better idea how this should be fixed?
>>
>> Regards,
>> Rui
>>
>> -- Forwarded message --
>> From: ruiv.wang at gmail.com
>> Date: Thu,  4 Dec 2014 22:11:35 +0800
>> Subject: [PATCH] drm: fb helper should avoid sleeping in panic context
>> To: airlied at redhat.com, daniel.vetter at ffwll.ch, tony.luck at intel.com,
>> bp at alien8.de, aris at redhat.com, rui.y.wang at intel.com
>> Cc: linux-kernel at vger.kernel.org
>>
>> From: Rui Wang 
>>
>> There are still some places in the fb helper that need to avoid
>> sleeping in panic context. Here's an example:
>>
>> [   65.615496] bad: scheduling from the idle thread!
>> [   65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G   ME
>>  3.18.0-rc4-7-default+ #20
>>
>> [   65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND,
>> BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
>> [   65.641923]  88087f693d80 88087f689878 81566db9
>> 
>> [   65.650226]  88087f693d80 88087f689898 810871ff
>> 88046eb3e0d0
>> [   65.658527]  88087f693d80 88087f6898c8 8107c1fa
>> 00017f6898b8
>> [   65.666830] Call Trace:
>> [   65.669557]  <#MC>  [] dump_stack+0x46/0x58
>> [   65.675994]  [] dequeue_task_idle+0x2f/0x40
>> [   65.682412]  [] dequeue_task+0x5a/0x80
>> [   65.688345]  [] deactivate_task+0x23/0x30
>> [   65.694569]  [] __schedule+0x580/0x7f0
>> [   65.700502]  [] schedule_preempt_disabled+0x29/0x70
>> [   65.707696]  [] __ww_mutex_lock_slowpath+0xb8/0x162
>> [   65.714891]  [] __ww_mutex_lock+0x53/0x85
>> [   65.721125]  [] drm_modeset_lock+0x3d/0x110 [drm]
>> [   65.728132]  [] __drm_modeset_lock_all+0x8a/0x120
>> [drm]
>> [   65.735721]  [] drm_modeset_lock_all+0x10/0x30 [drm]
>> [   65.743015]  []
>> drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
>> [   65.751857]  [] fb_pan_display+0xd1/0x1a0
>> [   65.758081]  [] bit_update_start+0x20/0x50
>> [   65.764400]  [] fbcon_switch+0x3a2/0x550
>> [   65.770528]  [] redraw_screen+0x189/0x240
>> [   65.776750]  [] fbcon_blank+0x20a/0x2d0
>> [   65.782778]  [] ? erst_writer+0x209/0x330
>> [   65.789002]  [] ? internal_add_timer+0x63/0x80
>> [   65.795710]  [] ? mod_timer+0x127/0x1e0
>> [   65.801740]  [] do_unblank_screen+0xa8/0x1d0
>> [   65.808255]  [] unblank_screen+0x10/0x20
>> [   65.814381]  [] bust_spinlocks+0x19/0x40
>> [   65.820508]  [] panic+0x106/0x1f5
>> [   65.825955]  [] mce_panic+0x2ac/0x2e0
>> [   65.831789]  [] ? delay_tsc+0x4a/0x80
>> [   65.837625]  [] do_machine_check+0xbaf/0xbf0
>> [   65.844138]  [] ? intel_idle+0xc7/0x150
>> [   65.850166]  [] machine_check+0x1f/0x30
>> [   65.856195]  [] ? intel_idle+0xc7/0x150
>> [   65.86]  <>  []
>> cpuidle_enter_state+0x55/0x170
>> [   65.869823]  [] cpuidle_enter+0x17/0x20
>> [   65.875852]  [] cpu_startup_entry+0x2d8/0x370
>> [   65.882467]  [] start_secondary+0x159/0x180
>>
>> There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
>> purpose. We can leverage that without reinventing anything. This patch
>> works with the latest kernel.
>>
>> Signed-off-by: Rui Wang 
>> ---
>>  drivers/gpu/drm/drm_fb_helper.c |8 ++--
>>  1 files changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_fb_helper.c
>> b/drivers/gpu/drm/drm_fb_helper.c
>> index 0c0c39b..70dd2f4 100644
>> --- a/drivers/gpu/drm/drm_fb_helper.c
>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>> @@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap,
>> struct fb_info *info)
>> int i, j, rc = 0;
>> int start;
>>
>> -   drm_modeset_lock_all(dev);
>> +   if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
>> +   return -EBUSY;
>> +   }
>> if (!drm_fb_helper_is_bound(fb_helper)) {
>> drm_modeset_unlock_all(dev);
>> return -EBUSY;
>> @@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo
>> *var,
>> int ret = 0;
>> int i;
>>
>> -   drm_modeset_lock_all(

[PATCH] drm: fb helper should avoid sleeping in panic context

2014-12-10 Thread rui wang 
Hi All,

Any comment ? Or any better idea how this should be fixed?

Regards,
Rui

-- Forwarded message --
From: ruiv.w...@gmail.com
Date: Thu,  4 Dec 2014 22:11:35 +0800
Subject: [PATCH] drm: fb helper should avoid sleeping in panic context
To: airlied at redhat.com, daniel.vetter at ffwll.ch, tony.luck at intel.com,
bp at alien8.de, aris at redhat.com, rui.y.wang at intel.com
Cc: linux-kernel at vger.kernel.org

From: Rui Wang <rui.y.w...@intel.com>

There are still some places in the fb helper that need to avoid
sleeping in panic context. Here's an example:

[   65.615496] bad: scheduling from the idle thread!
[   65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G   ME
 3.18.0-rc4-7-default+ #20

[   65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND,
BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
[   65.641923]  88087f693d80 88087f689878 81566db9

[   65.650226]  88087f693d80 88087f689898 810871ff
88046eb3e0d0
[   65.658527]  88087f693d80 88087f6898c8 8107c1fa
00017f6898b8
[   65.666830] Call Trace:
[   65.669557]  <#MC>  [] dump_stack+0x46/0x58
[   65.675994]  [] dequeue_task_idle+0x2f/0x40
[   65.682412]  [] dequeue_task+0x5a/0x80
[   65.688345]  [] deactivate_task+0x23/0x30
[   65.694569]  [] __schedule+0x580/0x7f0
[   65.700502]  [] schedule_preempt_disabled+0x29/0x70
[   65.707696]  [] __ww_mutex_lock_slowpath+0xb8/0x162
[   65.714891]  [] __ww_mutex_lock+0x53/0x85
[   65.721125]  [] drm_modeset_lock+0x3d/0x110 [drm]
[   65.728132]  [] __drm_modeset_lock_all+0x8a/0x120 [drm]
[   65.735721]  [] drm_modeset_lock_all+0x10/0x30 [drm]
[   65.743015]  []
drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
[   65.751857]  [] fb_pan_display+0xd1/0x1a0
[   65.758081]  [] bit_update_start+0x20/0x50
[   65.764400]  [] fbcon_switch+0x3a2/0x550
[   65.770528]  [] redraw_screen+0x189/0x240
[   65.776750]  [] fbcon_blank+0x20a/0x2d0
[   65.782778]  [] ? erst_writer+0x209/0x330
[   65.789002]  [] ? internal_add_timer+0x63/0x80
[   65.795710]  [] ? mod_timer+0x127/0x1e0
[   65.801740]  [] do_unblank_screen+0xa8/0x1d0
[   65.808255]  [] unblank_screen+0x10/0x20
[   65.814381]  [] bust_spinlocks+0x19/0x40
[   65.820508]  [] panic+0x106/0x1f5
[   65.825955]  [] mce_panic+0x2ac/0x2e0
[   65.831789]  [] ? delay_tsc+0x4a/0x80
[   65.837625]  [] do_machine_check+0xbaf/0xbf0
[   65.844138]  [] ? intel_idle+0xc7/0x150
[   65.850166]  [] machine_check+0x1f/0x30
[   65.856195]  [] ? intel_idle+0xc7/0x150
[   65.86]  <>  [] cpuidle_enter_state+0x55/0x170
[   65.869823]  [] cpuidle_enter+0x17/0x20
[   65.875852]  [] cpu_startup_entry+0x2d8/0x370
[   65.882467]  [] start_secondary+0x159/0x180

There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
purpose. We can leverage that without reinventing anything. This patch
works with the latest kernel.

Signed-off-by: Rui Wang 
---
 drivers/gpu/drm/drm_fb_helper.c |8 ++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 0c0c39b..70dd2f4 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap,
struct fb_info *info)
int i, j, rc = 0;
int start;

-   drm_modeset_lock_all(dev);
+   if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+   return -EBUSY;
+   }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
@@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
int ret = 0;
int i;

-   drm_modeset_lock_all(dev);
+   if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
+   return -EBUSY;
+   }
if (!drm_fb_helper_is_bound(fb_helper)) {
drm_modeset_unlock_all(dev);
return -EBUSY;
-- 
1.7.5.4

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[PATCH] drm: fb helper should avoid sleeping in panic context

2014-12-09 Thread Rob Clark 
oh, whoops.. gmail hiding quoted text..

yeah, that looks sane,

Reviewed-by: Rob Clark 

On Tue, Dec 9, 2014 at 7:55 PM, rui wang  wrote:
> Hi Rob,
> Yes it's exactly what I'm doing. Please scroll down and review my patch.
>
> Thanks
> Rui
>
> On 12/10/14, Rob Clark  wrote:
>> perhaps fb helpers could use __drm_modeset_lock_all() w/ trylock=true
>> in panic context?
>>
>> BR,
>> -R
>>
>> On Tue, Dec 9, 2014 at 7:09 PM, rui wang  wrote:
>>> Hi All,
>>>
>>> Any comment ? Or any better idea how this should be fixed?
>>>
>>> Regards,
>>> Rui
>>>
>>> ---------- Forwarded message --
>>> From: ruiv.wang at gmail.com
>>> Date: Thu,  4 Dec 2014 22:11:35 +0800
>>> Subject: [PATCH] drm: fb helper should avoid sleeping in panic context
>>> To: airlied at redhat.com, daniel.vetter at ffwll.ch, tony.luck at 
>>> intel.com,
>>> bp at alien8.de, aris at redhat.com, rui.y.wang at intel.com
>>> Cc: linux-kernel at vger.kernel.org
>>>
>>> From: Rui Wang 
>>>
>>> There are still some places in the fb helper that need to avoid
>>> sleeping in panic context. Here's an example:
>>>
>>> [   65.615496] bad: scheduling from the idle thread!
>>> [   65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G   ME
>>>  3.18.0-rc4-7-default+ #20
>>>
>>> [   65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND,
>>> BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
>>> [   65.641923]  88087f693d80 88087f689878 81566db9
>>> 
>>> [   65.650226]  88087f693d80 88087f689898 810871ff
>>> 88046eb3e0d0
>>> [   65.658527]  88087f693d80 88087f6898c8 8107c1fa
>>> 00017f6898b8
>>> [   65.666830] Call Trace:
>>> [   65.669557]  <#MC>  [] dump_stack+0x46/0x58
>>> [   65.675994]  [] dequeue_task_idle+0x2f/0x40
>>> [   65.682412]  [] dequeue_task+0x5a/0x80
>>> [   65.688345]  [] deactivate_task+0x23/0x30
>>> [   65.694569]  [] __schedule+0x580/0x7f0
>>> [   65.700502]  [] schedule_preempt_disabled+0x29/0x70
>>> [   65.707696]  [] __ww_mutex_lock_slowpath+0xb8/0x162
>>> [   65.714891]  [] __ww_mutex_lock+0x53/0x85
>>> [   65.721125]  [] drm_modeset_lock+0x3d/0x110 [drm]
>>> [   65.728132]  [] __drm_modeset_lock_all+0x8a/0x120
>>> [drm]
>>> [   65.735721]  [] drm_modeset_lock_all+0x10/0x30 [drm]
>>> [   65.743015]  []
>>> drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
>>> [   65.751857]  [] fb_pan_display+0xd1/0x1a0
>>> [   65.758081]  [] bit_update_start+0x20/0x50
>>> [   65.764400]  [] fbcon_switch+0x3a2/0x550
>>> [   65.770528]  [] redraw_screen+0x189/0x240
>>> [   65.776750]  [] fbcon_blank+0x20a/0x2d0
>>> [   65.782778]  [] ? erst_writer+0x209/0x330
>>> [   65.789002]  [] ? internal_add_timer+0x63/0x80
>>> [   65.795710]  [] ? mod_timer+0x127/0x1e0
>>> [   65.801740]  [] do_unblank_screen+0xa8/0x1d0
>>> [   65.808255]  [] unblank_screen+0x10/0x20
>>> [   65.814381]  [] bust_spinlocks+0x19/0x40
>>> [   65.820508]  [] panic+0x106/0x1f5
>>> [   65.825955]  [] mce_panic+0x2ac/0x2e0
>>> [   65.831789]  [] ? delay_tsc+0x4a/0x80
>>> [   65.837625]  [] do_machine_check+0xbaf/0xbf0
>>> [   65.844138]  [] ? intel_idle+0xc7/0x150
>>> [   65.850166]  [] machine_check+0x1f/0x30
>>> [   65.856195]  [] ? intel_idle+0xc7/0x150
>>> [   65.86]  <>  []
>>> cpuidle_enter_state+0x55/0x170
>>> [   65.869823]  [] cpuidle_enter+0x17/0x20
>>> [   65.875852]  [] cpu_startup_entry+0x2d8/0x370
>>> [   65.882467]  [] start_secondary+0x159/0x180
>>>
>>> There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
>>> purpose. We can leverage that without reinventing anything. This patch
>>> works with the latest kernel.
>>>
>>> Signed-off-by: Rui Wang 
>>> ---
>>>  drivers/gpu/drm/drm_fb_helper.c |8 ++--
>>>  1 files changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_fb_helper.c
>>> b/drivers/gpu/drm/drm_fb_helper.c
>>> index 0c0c39b..70dd2f4 100644
>>> --- a/drivers/gpu/drm/drm_fb_helper.c
>>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>>> @@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap,
>>> struct fb_info *info)
>>> int i, j, rc = 0;

[PATCH] drm: fb helper should avoid sleeping in panic context

2014-12-09 Thread Rob Clark 
perhaps fb helpers could use __drm_modeset_lock_all() w/ trylock=true
in panic context?

BR,
-R

On Tue, Dec 9, 2014 at 7:09 PM, rui wang  wrote:
> Hi All,
>
> Any comment ? Or any better idea how this should be fixed?
>
> Regards,
> Rui
>
> -- Forwarded message --
> From: ruiv.wang at gmail.com
> Date: Thu,  4 Dec 2014 22:11:35 +0800
> Subject: [PATCH] drm: fb helper should avoid sleeping in panic context
> To: airlied at redhat.com, daniel.vetter at ffwll.ch, tony.luck at intel.com,
> bp at alien8.de, aris at redhat.com, rui.y.wang at intel.com
> Cc: linux-kernel at vger.kernel.org
>
> From: Rui Wang 
>
> There are still some places in the fb helper that need to avoid
> sleeping in panic context. Here's an example:
>
> [   65.615496] bad: scheduling from the idle thread!
> [   65.620747] CPU: 92 PID: 0 Comm: swapper/92 Tainted: G   ME
>  3.18.0-rc4-7-default+ #20
>
> [   65.630364] Hardware name: Intel Corporation BRICKLAND/BRICKLAND,
> BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
> [   65.641923]  88087f693d80 88087f689878 81566db9
> 
> [   65.650226]  88087f693d80 88087f689898 810871ff
> 88046eb3e0d0
> [   65.658527]  88087f693d80 88087f6898c8 8107c1fa
> 00017f6898b8
> [   65.666830] Call Trace:
> [   65.669557]  <#MC>  [] dump_stack+0x46/0x58
> [   65.675994]  [] dequeue_task_idle+0x2f/0x40
> [   65.682412]  [] dequeue_task+0x5a/0x80
> [   65.688345]  [] deactivate_task+0x23/0x30
> [   65.694569]  [] __schedule+0x580/0x7f0
> [   65.700502]  [] schedule_preempt_disabled+0x29/0x70
> [   65.707696]  [] __ww_mutex_lock_slowpath+0xb8/0x162
> [   65.714891]  [] __ww_mutex_lock+0x53/0x85
> [   65.721125]  [] drm_modeset_lock+0x3d/0x110 [drm]
> [   65.728132]  [] __drm_modeset_lock_all+0x8a/0x120 [drm]
> [   65.735721]  [] drm_modeset_lock_all+0x10/0x30 [drm]
> [   65.743015]  []
> drm_fb_helper_pan_display+0x2f/0xf0 [drm_kms_helper]
> [   65.751857]  [] fb_pan_display+0xd1/0x1a0
> [   65.758081]  [] bit_update_start+0x20/0x50
> [   65.764400]  [] fbcon_switch+0x3a2/0x550
> [   65.770528]  [] redraw_screen+0x189/0x240
> [   65.776750]  [] fbcon_blank+0x20a/0x2d0
> [   65.782778]  [] ? erst_writer+0x209/0x330
> [   65.789002]  [] ? internal_add_timer+0x63/0x80
> [   65.795710]  [] ? mod_timer+0x127/0x1e0
> [   65.801740]  [] do_unblank_screen+0xa8/0x1d0
> [   65.808255]  [] unblank_screen+0x10/0x20
> [   65.814381]  [] bust_spinlocks+0x19/0x40
> [   65.820508]  [] panic+0x106/0x1f5
> [   65.825955]  [] mce_panic+0x2ac/0x2e0
> [   65.831789]  [] ? delay_tsc+0x4a/0x80
> [   65.837625]  [] do_machine_check+0xbaf/0xbf0
> [   65.844138]  [] ? intel_idle+0xc7/0x150
> [   65.850166]  [] machine_check+0x1f/0x30
> [   65.856195]  [] ? intel_idle+0xc7/0x150
> [   65.86]  <>  [] cpuidle_enter_state+0x55/0x170
> [   65.869823]  [] cpuidle_enter+0x17/0x20
> [   65.875852]  [] cpu_startup_entry+0x2d8/0x370
> [   65.882467]  [] start_secondary+0x159/0x180
>
> There's __drm_modeset_lock_all() which Daniel Vetter introduced for this
> purpose. We can leverage that without reinventing anything. This patch
> works with the latest kernel.
>
> Signed-off-by: Rui Wang 
> ---
>  drivers/gpu/drm/drm_fb_helper.c |8 ++--
>  1 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 0c0c39b..70dd2f4 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -732,7 +732,9 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap,
> struct fb_info *info)
> int i, j, rc = 0;
> int start;
>
> -   drm_modeset_lock_all(dev);
> +   if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
> +   return -EBUSY;
> +   }
> if (!drm_fb_helper_is_bound(fb_helper)) {
> drm_modeset_unlock_all(dev);
> return -EBUSY;
> @@ -910,7 +912,9 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo 
> *var,
> int ret = 0;
> int i;
>
> -   drm_modeset_lock_all(dev);
> +   if (__drm_modeset_lock_all(dev, !!oops_in_progress)) {
> +   return -EBUSY;
> +   }
> if (!drm_fb_helper_is_bound(fb_helper)) {
> drm_modeset_unlock_all(dev);
> return -EBUSY;
> --
> 1.7.5.4
>
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