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* get/put_cpu() usage in block/blk-mq.c
@ 2017-05-09  6:07 Mike Galbraith
  2017-05-09 14:53 ` Jens Axboe
  0 siblings, 1 reply; 10+ messages in thread
From: Mike Galbraith @ 2017-05-09  6:07 UTC (permalink / raw)
  To: Jens Axboe; +Cc: LKML

Hi Jens,

I was about to fix up this splat..

[  445.022141] loop: module loaded
[  445.078116] BUG: using smp_processor_id() in preemptible [00000000] code: loop0/3801
[  445.085873] caller is debug_smp_processor_id+0x17/0x20
[  445.091016] CPU: 7 PID: 3801 Comm: loop0 Tainted: G            E   4.12.0-default #40
[  445.098838] Hardware name: IBM System x3550 M3 -[7944K3G]-/69Y5698     , BIOS -[D6E150AUS-1.10]- 12/15/2010
[  445.108564] Call Trace:
[  445.111016]  dump_stack+0x65/0x89
[  445.114330]  check_preemption_disabled+0xde/0xf0
[  445.118945]  debug_smp_processor_id+0x17/0x20
[  445.123300]  blk_stat_add+0xb0/0x130
[  445.126876]  __blk_mq_complete_request+0xb5/0x150
[  445.131575]  blk_mq_complete_request+0x16/0x20
[  445.136020]  loop_queue_work+0x5f/0xaa0 [loop]
[  445.140461]  ? _raw_spin_unlock_irq+0x21/0x40
[  445.144816]  ? finish_task_switch+0x85/0x270
[  445.149085]  ? __schedule+0x291/0x8c0
[  445.152747]  kthread_worker_fn+0xc2/0x1d0
[  445.156754]  kthread+0x114/0x150
[  445.159983]  ? __kthread_init_worker+0xb0/0xb0
[  445.164424]  ? kthread_park+0x60/0x60
[  445.168085]  ret_from_fork+0x2c/0x40

..but then noticed that __blk_mq_run_hw_queue() is also called under
get_cpu(), but recently grew a might_sleep(), so maybe wants some block
layer eyeballs.

	-Mike

^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: get/put_cpu() usage in block/blk-mq.c
  2017-05-09  6:07 get/put_cpu() usage in block/blk-mq.c Mike Galbraith
@ 2017-05-09 14:53 ` Jens Axboe
  2017-05-09 15:04   ` Mike Galbraith
  0 siblings, 1 reply; 10+ messages in thread
From: Jens Axboe @ 2017-05-09 14:53 UTC (permalink / raw)
  To: Mike Galbraith; +Cc: LKML

On 05/09/2017 12:07 AM, Mike Galbraith wrote:
> Hi Jens,
> 
> I was about to fix up this splat..
> 
> [  445.022141] loop: module loaded
> [  445.078116] BUG: using smp_processor_id() in preemptible [00000000] code: loop0/3801
> [  445.085873] caller is debug_smp_processor_id+0x17/0x20
> [  445.091016] CPU: 7 PID: 3801 Comm: loop0 Tainted: G            E   4.12.0-default #40
> [  445.098838] Hardware name: IBM System x3550 M3 -[7944K3G]-/69Y5698     , BIOS -[D6E150AUS-1.10]- 12/15/2010
> [  445.108564] Call Trace:
> [  445.111016]  dump_stack+0x65/0x89
> [  445.114330]  check_preemption_disabled+0xde/0xf0
> [  445.118945]  debug_smp_processor_id+0x17/0x20
> [  445.123300]  blk_stat_add+0xb0/0x130
> [  445.126876]  __blk_mq_complete_request+0xb5/0x150
> [  445.131575]  blk_mq_complete_request+0x16/0x20
> [  445.136020]  loop_queue_work+0x5f/0xaa0 [loop]
> [  445.140461]  ? _raw_spin_unlock_irq+0x21/0x40
> [  445.144816]  ? finish_task_switch+0x85/0x270
> [  445.149085]  ? __schedule+0x291/0x8c0
> [  445.152747]  kthread_worker_fn+0xc2/0x1d0
> [  445.156754]  kthread+0x114/0x150
> [  445.159983]  ? __kthread_init_worker+0xb0/0xb0
> [  445.164424]  ? kthread_park+0x60/0x60
> [  445.168085]  ret_from_fork+0x2c/0x40

Is it from this_cpu_ptr() in blk_stat_add()?

> ..but then noticed that __blk_mq_run_hw_queue() is also called under
> get_cpu(), but recently grew a might_sleep(), so maybe wants some block
> layer eyeballs.

That part is fine. The might sleep depends on BLOCKING being set in
the hardware queue flags. And if that is set, then we don't call
it under get_cpu().

-- 
Jens Axboe

^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: get/put_cpu() usage in block/blk-mq.c
  2017-05-09 14:53 ` Jens Axboe
@ 2017-05-09 15:04   ` Mike Galbraith
  2017-05-09 15:13     ` Jens Axboe
  0 siblings, 1 reply; 10+ messages in thread
From: Mike Galbraith @ 2017-05-09 15:04 UTC (permalink / raw)
  To: Jens Axboe; +Cc: LKML

On Tue, 2017-05-09 at 08:53 -0600, Jens Axboe wrote:
> On 05/09/2017 12:07 AM, Mike Galbraith wrote:
> > Hi Jens,
> > 
> > I was about to fix up this splat..
> > 
> > [  445.022141] loop: module loaded
> > [  445.078116] BUG: using smp_processor_id() in preemptible [00000000] code: loop0/3801
> > [  445.085873] caller is debug_smp_processor_id+0x17/0x20
> > [  445.091016] CPU: 7 PID: 3801 Comm: loop0 Tainted: G            E   4.12.0-default #40
> > [  445.098838] Hardware name: IBM System x3550 M3 -[7944K3G]-/69Y5698     , BIOS -[D6E150AUS-1.10]- 12/15/2010
> > [  445.108564] Call Trace:
> > [  445.111016]  dump_stack+0x65/0x89
> > [  445.114330]  check_preemption_disabled+0xde/0xf0
> > [  445.118945]  debug_smp_processor_id+0x17/0x20
> > [  445.123300]  blk_stat_add+0xb0/0x130
> > [  445.126876]  __blk_mq_complete_request+0xb5/0x150
> > [  445.131575]  blk_mq_complete_request+0x16/0x20
> > [  445.136020]  loop_queue_work+0x5f/0xaa0 [loop]
> > [  445.140461]  ? _raw_spin_unlock_irq+0x21/0x40
> > [  445.144816]  ? finish_task_switch+0x85/0x270
> > [  445.149085]  ? __schedule+0x291/0x8c0
> > [  445.152747]  kthread_worker_fn+0xc2/0x1d0
> > [  445.156754]  kthread+0x114/0x150
> > [  445.159983]  ? __kthread_init_worker+0xb0/0xb0
> > [  445.164424]  ? kthread_park+0x60/0x60
> > [  445.168085]  ret_from_fork+0x2c/0x40
> 
> Is it from this_cpu_ptr() in blk_stat_add()?

Yeah.

> > ..but then noticed that __blk_mq_run_hw_queue() is also called under
> > get_cpu(), but recently grew a might_sleep(), so maybe wants some block
> > layer eyeballs.
> 
> That part is fine. The might sleep depends on BLOCKING being set in
> the hardware queue flags. And if that is set, then we don't call
> it under get_cpu().

Ah, right.

	-Mike

^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: get/put_cpu() usage in block/blk-mq.c
  2017-05-09 15:04   ` Mike Galbraith
@ 2017-05-09 15:13     ` Jens Axboe
  2017-05-09 15:15       ` Jens Axboe
  0 siblings, 1 reply; 10+ messages in thread
From: Jens Axboe @ 2017-05-09 15:13 UTC (permalink / raw)
  To: Mike Galbraith; +Cc: LKML

On 05/09/2017 09:04 AM, Mike Galbraith wrote:
> On Tue, 2017-05-09 at 08:53 -0600, Jens Axboe wrote:
>> On 05/09/2017 12:07 AM, Mike Galbraith wrote:
>>> Hi Jens,
>>>
>>> I was about to fix up this splat..
>>>
>>> [  445.022141] loop: module loaded
>>> [  445.078116] BUG: using smp_processor_id() in preemptible [00000000] code: loop0/3801
>>> [  445.085873] caller is debug_smp_processor_id+0x17/0x20
>>> [  445.091016] CPU: 7 PID: 3801 Comm: loop0 Tainted: G            E   4.12.0-default #40
>>> [  445.098838] Hardware name: IBM System x3550 M3 -[7944K3G]-/69Y5698     , BIOS -[D6E150AUS-1.10]- 12/15/2010
>>> [  445.108564] Call Trace:
>>> [  445.111016]  dump_stack+0x65/0x89
>>> [  445.114330]  check_preemption_disabled+0xde/0xf0
>>> [  445.118945]  debug_smp_processor_id+0x17/0x20
>>> [  445.123300]  blk_stat_add+0xb0/0x130
>>> [  445.126876]  __blk_mq_complete_request+0xb5/0x150
>>> [  445.131575]  blk_mq_complete_request+0x16/0x20
>>> [  445.136020]  loop_queue_work+0x5f/0xaa0 [loop]
>>> [  445.140461]  ? _raw_spin_unlock_irq+0x21/0x40
>>> [  445.144816]  ? finish_task_switch+0x85/0x270
>>> [  445.149085]  ? __schedule+0x291/0x8c0
>>> [  445.152747]  kthread_worker_fn+0xc2/0x1d0
>>> [  445.156754]  kthread+0x114/0x150
>>> [  445.159983]  ? __kthread_init_worker+0xb0/0xb0
>>> [  445.164424]  ? kthread_park+0x60/0x60
>>> [  445.168085]  ret_from_fork+0x2c/0x40
>>
>> Is it from this_cpu_ptr() in blk_stat_add()?
> 
> Yeah.

So why is this complaining, doesn't rcu_read_lock() disable
preemption?

-- 
Jens Axboe

^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: get/put_cpu() usage in block/blk-mq.c
  2017-05-09 15:13     ` Jens Axboe
@ 2017-05-09 15:15       ` Jens Axboe
  2017-05-09 15:40         ` Mike Galbraith
  0 siblings, 1 reply; 10+ messages in thread
From: Jens Axboe @ 2017-05-09 15:15 UTC (permalink / raw)
  To: Mike Galbraith; +Cc: LKML

On 05/09/2017 09:13 AM, Jens Axboe wrote:
> On 05/09/2017 09:04 AM, Mike Galbraith wrote:
>> On Tue, 2017-05-09 at 08:53 -0600, Jens Axboe wrote:
>>> On 05/09/2017 12:07 AM, Mike Galbraith wrote:
>>>> Hi Jens,
>>>>
>>>> I was about to fix up this splat..
>>>>
>>>> [  445.022141] loop: module loaded
>>>> [  445.078116] BUG: using smp_processor_id() in preemptible [00000000] code: loop0/3801
>>>> [  445.085873] caller is debug_smp_processor_id+0x17/0x20
>>>> [  445.091016] CPU: 7 PID: 3801 Comm: loop0 Tainted: G            E   4.12.0-default #40
>>>> [  445.098838] Hardware name: IBM System x3550 M3 -[7944K3G]-/69Y5698     , BIOS -[D6E150AUS-1.10]- 12/15/2010
>>>> [  445.108564] Call Trace:
>>>> [  445.111016]  dump_stack+0x65/0x89
>>>> [  445.114330]  check_preemption_disabled+0xde/0xf0
>>>> [  445.118945]  debug_smp_processor_id+0x17/0x20
>>>> [  445.123300]  blk_stat_add+0xb0/0x130
>>>> [  445.126876]  __blk_mq_complete_request+0xb5/0x150
>>>> [  445.131575]  blk_mq_complete_request+0x16/0x20
>>>> [  445.136020]  loop_queue_work+0x5f/0xaa0 [loop]
>>>> [  445.140461]  ? _raw_spin_unlock_irq+0x21/0x40
>>>> [  445.144816]  ? finish_task_switch+0x85/0x270
>>>> [  445.149085]  ? __schedule+0x291/0x8c0
>>>> [  445.152747]  kthread_worker_fn+0xc2/0x1d0
>>>> [  445.156754]  kthread+0x114/0x150
>>>> [  445.159983]  ? __kthread_init_worker+0xb0/0xb0
>>>> [  445.164424]  ? kthread_park+0x60/0x60
>>>> [  445.168085]  ret_from_fork+0x2c/0x40
>>>
>>> Is it from this_cpu_ptr() in blk_stat_add()?
>>
>> Yeah.
> 
> So why is this complaining, doesn't rcu_read_lock() disable
> preemption?

Ah, I guess it doesn't if PREEMPT_RCU is set. How about the below?


diff --git a/block/blk-stat.c b/block/blk-stat.c
index 6c2f40940439..022f5925a427 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -96,13 +96,16 @@ void blk_stat_add(struct request *rq)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(cb, &q->stats->callbacks, list) {
-		if (blk_stat_is_active(cb)) {
-			bucket = cb->bucket_fn(rq);
-			if (bucket < 0)
-				continue;
-			stat = &this_cpu_ptr(cb->cpu_stat)[bucket];
-			__blk_stat_add(stat, value);
-		}
+		if (!blk_stat_is_active(cb))
+			continue;
+
+		bucket = cb->bucket_fn(rq);
+		if (bucket < 0)
+			continue;
+
+		stat = &get_cpu_var(cb->cpu_stat)[bucket];
+		__blk_stat_add(stat, value);
+		put_cpu_var(cb->cpu_stat);
 	}
 	rcu_read_unlock();
 }

-- 
Jens Axboe

^ permalink raw reply related	[flat|nested] 10+ messages in thread
* Re: get/put_cpu() usage in block/blk-mq.c
  2017-05-09 15:15       ` Jens Axboe
@ 2017-05-09 15:40         ` Mike Galbraith
  2017-05-09 15:45           ` Jens Axboe
  0 siblings, 1 reply; 10+ messages in thread
From: Mike Galbraith @ 2017-05-09 15:40 UTC (permalink / raw)
  To: Jens Axboe; +Cc: LKML

On Tue, 2017-05-09 at 09:15 -0600, Jens Axboe wrote:
> On 05/09/2017 09:13 AM, Jens Axboe wrote:
> > On 05/09/2017 09:04 AM, Mike Galbraith wrote:
> > > On Tue, 2017-05-09 at 08:53 -0600, Jens Axboe wrote:
> > > > On 05/09/2017 12:07 AM, Mike Galbraith wrote:
> > > > > Hi Jens,
> > > > > 
> > > > > I was about to fix up this splat..
> > > > > 
> > > > > [  445.022141] loop: module loaded
> > > > > [  445.078116] BUG: using smp_processor_id() in preemptible
> > > > > [00000000] code: loop0/3801
> > > > > [  445.085873] caller is debug_smp_processor_id+0x17/0x20
> > > > > [  445.091016] CPU: 7 PID: 3801 Comm: loop0 Tainted: G       
> > > > >      E   4.12.0-default #40
> > > > > [  445.098838] Hardware name: IBM System x3550 M3 -[7944K3G]
> > > > > -/69Y5698     , BIOS -[D6E150AUS-1.10]- 12/15/2010
> > > > > [  445.108564] Call Trace:
> > > > > [  445.111016]  dump_stack+0x65/0x89
> > > > > [  445.114330]  check_preemption_disabled+0xde/0xf0
> > > > > [  445.118945]  debug_smp_processor_id+0x17/0x20
> > > > > [  445.123300]  blk_stat_add+0xb0/0x130
> > > > > [  445.126876]  __blk_mq_complete_request+0xb5/0x150
> > > > > [  445.131575]  blk_mq_complete_request+0x16/0x20
> > > > > [  445.136020]  loop_queue_work+0x5f/0xaa0 [loop]
> > > > > [  445.140461]  ? _raw_spin_unlock_irq+0x21/0x40
> > > > > [  445.144816]  ? finish_task_switch+0x85/0x270
> > > > > [  445.149085]  ? __schedule+0x291/0x8c0
> > > > > [  445.152747]  kthread_worker_fn+0xc2/0x1d0
> > > > > [  445.156754]  kthread+0x114/0x150
> > > > > [  445.159983]  ? __kthread_init_worker+0xb0/0xb0
> > > > > [  445.164424]  ? kthread_park+0x60/0x60
> > > > > [  445.168085]  ret_from_fork+0x2c/0x40
> > > > 
> > > > Is it from this_cpu_ptr() in blk_stat_add()?
> > > 
> > > Yeah.
> > 
> > So why is this complaining, doesn't rcu_read_lock() disable
> > preemption?
> 
> Ah, I guess it doesn't if PREEMPT_RCU is set. How about the below?

Should do it.  I was about to run LTP (where it turned up) again
anyway, I'll add this.  No news is good news, what you should hear.

> diff --git a/block/blk-stat.c b/block/blk-stat.c
> index 6c2f40940439..022f5925a427 100644
> --- a/block/blk-stat.c
> +++ b/block/blk-stat.c
> @@ -96,13 +96,16 @@ void blk_stat_add(struct request *rq)
>  
>  	rcu_read_lock();
>  	list_for_each_entry_rcu(cb, &q->stats->callbacks, list) {
> -		if (blk_stat_is_active(cb)) {
> -			bucket = cb->bucket_fn(rq);
> -			if (bucket < 0)
> -				continue;
> -			stat = &this_cpu_ptr(cb->cpu_stat)[bucket];
> -			__blk_stat_add(stat, value);
> -		}
> +		if (!blk_stat_is_active(cb))
> +			continue;
> +
> +		bucket = cb->bucket_fn(rq);
> +		if (bucket < 0)
> +			continue;
> +
> +		stat = &get_cpu_var(cb->cpu_stat)[bucket];
> +		__blk_stat_add(stat, value);
> +		put_cpu_var(cb->cpu_stat);
>  	}
>  	rcu_read_unlock();
>  }
> 

^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: get/put_cpu() usage in block/blk-mq.c
  2017-05-09 15:40         ` Mike Galbraith
@ 2017-05-09 15:45           ` Jens Axboe
  2017-05-09 16:26             ` Mike Galbraith
  0 siblings, 1 reply; 10+ messages in thread
From: Jens Axboe @ 2017-05-09 15:45 UTC (permalink / raw)
  To: Mike Galbraith; +Cc: LKML

On 05/09/2017 09:40 AM, Mike Galbraith wrote:
> On Tue, 2017-05-09 at 09:15 -0600, Jens Axboe wrote:
>> On 05/09/2017 09:13 AM, Jens Axboe wrote:
>>> On 05/09/2017 09:04 AM, Mike Galbraith wrote:
>>>> On Tue, 2017-05-09 at 08:53 -0600, Jens Axboe wrote:
>>>>> On 05/09/2017 12:07 AM, Mike Galbraith wrote:
>>>>>> Hi Jens,
>>>>>>
>>>>>> I was about to fix up this splat..
>>>>>>
>>>>>> [  445.022141] loop: module loaded
>>>>>> [  445.078116] BUG: using smp_processor_id() in preemptible
>>>>>> [00000000] code: loop0/3801
>>>>>> [  445.085873] caller is debug_smp_processor_id+0x17/0x20
>>>>>> [  445.091016] CPU: 7 PID: 3801 Comm: loop0 Tainted: G       
>>>>>>      E   4.12.0-default #40
>>>>>> [  445.098838] Hardware name: IBM System x3550 M3 -[7944K3G]
>>>>>> -/69Y5698     , BIOS -[D6E150AUS-1.10]- 12/15/2010
>>>>>> [  445.108564] Call Trace:
>>>>>> [  445.111016]  dump_stack+0x65/0x89
>>>>>> [  445.114330]  check_preemption_disabled+0xde/0xf0
>>>>>> [  445.118945]  debug_smp_processor_id+0x17/0x20
>>>>>> [  445.123300]  blk_stat_add+0xb0/0x130
>>>>>> [  445.126876]  __blk_mq_complete_request+0xb5/0x150
>>>>>> [  445.131575]  blk_mq_complete_request+0x16/0x20
>>>>>> [  445.136020]  loop_queue_work+0x5f/0xaa0 [loop]
>>>>>> [  445.140461]  ? _raw_spin_unlock_irq+0x21/0x40
>>>>>> [  445.144816]  ? finish_task_switch+0x85/0x270
>>>>>> [  445.149085]  ? __schedule+0x291/0x8c0
>>>>>> [  445.152747]  kthread_worker_fn+0xc2/0x1d0
>>>>>> [  445.156754]  kthread+0x114/0x150
>>>>>> [  445.159983]  ? __kthread_init_worker+0xb0/0xb0
>>>>>> [  445.164424]  ? kthread_park+0x60/0x60
>>>>>> [  445.168085]  ret_from_fork+0x2c/0x40
>>>>>
>>>>> Is it from this_cpu_ptr() in blk_stat_add()?
>>>>
>>>> Yeah.
>>>
>>> So why is this complaining, doesn't rcu_read_lock() disable
>>> preemption?
>>
>> Ah, I guess it doesn't if PREEMPT_RCU is set. How about the below?
> 
> Should do it.  I was about to run LTP (where it turned up) again
> anyway, I'll add this.  No news is good news, what you should hear.

Thanks, let me know, so I can add your tested-by (or whatever you
prefer).

-- 
Jens Axboe

^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: get/put_cpu() usage in block/blk-mq.c
  2017-05-09 15:45           ` Jens Axboe
@ 2017-05-09 16:26             ` Mike Galbraith
  2017-05-09 16:32               ` Jens Axboe
  0 siblings, 1 reply; 10+ messages in thread
From: Mike Galbraith @ 2017-05-09 16:26 UTC (permalink / raw)
  To: Jens Axboe; +Cc: LKML

On Tue, 2017-05-09 at 09:45 -0600, Jens Axboe wrote:

> > > > > > Is it from this_cpu_ptr() in blk_stat_add()?
> > > > > 
> > > > > Yeah.
> > > > 
> > > > So why is this complaining, doesn't rcu_read_lock() disable
> > > > preemption?
> > > 
> > > Ah, I guess it doesn't if PREEMPT_RCU is set. How about the
> > > below?
> > 
> > Should do it.  I was about to run LTP (where it turned up) again
> > anyway, I'll add this.  No news is good news, what you should hear.
> 
> Thanks, let me know, so I can add your tested-by (or whatever you
> prefer).

Sure, but s/get_cpu_var/get_cpu_ptr first.

	-MIke

^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: get/put_cpu() usage in block/blk-mq.c
  2017-05-09 16:26             ` Mike Galbraith
@ 2017-05-09 16:32               ` Jens Axboe
  2017-05-09 16:52                 ` Mike Galbraith
  0 siblings, 1 reply; 10+ messages in thread
From: Jens Axboe @ 2017-05-09 16:32 UTC (permalink / raw)
  To: Mike Galbraith; +Cc: LKML

On 05/09/2017 10:26 AM, Mike Galbraith wrote:
> On Tue, 2017-05-09 at 09:45 -0600, Jens Axboe wrote:
> 
>>>>>>> Is it from this_cpu_ptr() in blk_stat_add()?
>>>>>>
>>>>>> Yeah.
>>>>>
>>>>> So why is this complaining, doesn't rcu_read_lock() disable
>>>>> preemption?
>>>>
>>>> Ah, I guess it doesn't if PREEMPT_RCU is set. How about the
>>>> below?
>>>
>>> Should do it.  I was about to run LTP (where it turned up) again
>>> anyway, I'll add this.  No news is good news, what you should hear.
>>
>> Thanks, let me know, so I can add your tested-by (or whatever you
>> prefer).
> 
> Sure, but s/get_cpu_var/get_cpu_ptr first.

Doh.

diff --git a/block/blk-stat.c b/block/blk-stat.c
index 6c2f40940439..c52356d90fe3 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -96,13 +96,16 @@ void blk_stat_add(struct request *rq)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(cb, &q->stats->callbacks, list) {
-		if (blk_stat_is_active(cb)) {
-			bucket = cb->bucket_fn(rq);
-			if (bucket < 0)
-				continue;
-			stat = &this_cpu_ptr(cb->cpu_stat)[bucket];
-			__blk_stat_add(stat, value);
-		}
+		if (!blk_stat_is_active(cb))
+			continue;
+
+		bucket = cb->bucket_fn(rq);
+		if (bucket < 0)
+			continue;
+
+		stat = &get_cpu_ptr(cb->cpu_stat)[bucket];
+		__blk_stat_add(stat, value);
+		put_cpu_ptr(cb->cpu_stat);
 	}
 	rcu_read_unlock();
 }

-- 
Jens Axboe

^ permalink raw reply related	[flat|nested] 10+ messages in thread
* Re: get/put_cpu() usage in block/blk-mq.c
  2017-05-09 16:32               ` Jens Axboe
@ 2017-05-09 16:52                 ` Mike Galbraith
  0 siblings, 0 replies; 10+ messages in thread
From: Mike Galbraith @ 2017-05-09 16:52 UTC (permalink / raw)
  To: Jens Axboe; +Cc: LKML

On Tue, 2017-05-09 at 10:32 -0600, Jens Axboe wrote:

> > Sure, but s/get_cpu_var/get_cpu_ptr first.
> 
> Doh.

Ditto, box OTOH spotted the booboo instantly :)

	-Mike

^ permalink raw reply	[flat|nested] 10+ messages in thread
end of thread, other threads:[~2017-05-09 16:52 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-05-09  6:07 get/put_cpu() usage in block/blk-mq.c Mike Galbraith
2017-05-09 14:53 ` Jens Axboe
2017-05-09 15:04   ` Mike Galbraith
2017-05-09 15:13     ` Jens Axboe
2017-05-09 15:15       ` Jens Axboe
2017-05-09 15:40         ` Mike Galbraith
2017-05-09 15:45           ` Jens Axboe
2017-05-09 16:26             ` Mike Galbraith
2017-05-09 16:32               ` Jens Axboe
2017-05-09 16:52                 ` Mike Galbraith

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