* [PATCH] Fix scheduling-while-atomic problem in console_cpu_notify()
@ 2012-10-16 0:31 Paul E. McKenney
2012-10-16 4:35 ` Paul E. McKenney
0 siblings, 1 reply; 3+ messages in thread
From: Paul E. McKenney @ 2012-10-16 0:31 UTC (permalink / raw)
To: linux-kernel; +Cc: cernekee, torbenh, torvalds, tglx, srivatsa.bhat
The console_cpu_notify( function runs with interrupts disabled in
the CPU_DEAD case. It therefore cannot block, for example, as will
happen when it calls console_lock(). Therefore, remove the CPU_DEAD
leg of the switch statement to avoid this problem.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
diff --git a/kernel/printk.c b/kernel/printk.c
index 66a2ea3..8e23a14 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1889,7 +1889,6 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self,
{
switch (action) {
case CPU_ONLINE:
- case CPU_DEAD:
case CPU_DYING:
case CPU_DOWN_FAILED:
case CPU_UP_CANCELED:
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] Fix scheduling-while-atomic problem in console_cpu_notify()
2012-10-16 0:31 [PATCH] Fix scheduling-while-atomic problem in console_cpu_notify() Paul E. McKenney
@ 2012-10-16 4:35 ` Paul E. McKenney
2012-10-16 5:31 ` Srivatsa S. Bhat
0 siblings, 1 reply; 3+ messages in thread
From: Paul E. McKenney @ 2012-10-16 4:35 UTC (permalink / raw)
To: linux-kernel; +Cc: cernekee, torbenh, torvalds, tglx, srivatsa.bhat
On Mon, Oct 15, 2012 at 05:31:28PM -0700, Paul E. McKenney wrote:
> The console_cpu_notify( function runs with interrupts disabled in
> the CPU_DEAD case. It therefore cannot block, for example, as will
> happen when it calls console_lock(). Therefore, remove the CPU_DEAD
> leg of the switch statement to avoid this problem.
>
> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
s/CPU_DEAD/CPU_DYING/
Apparently it is a bad idea to compose and send a patch while in a
C++ standards committee meeting where people are arguing about async
futures... Fixed patch below.
Thanx, Paul
------------------------------------------------------------------------
printk: Fix scheduling-while-atomic problem in console_cpu_notify()
The console_cpu_notify( function runs with interrupts disabled in
the CPU_DYING case. It therefore cannot block, for example, as will
happen when it calls console_lock(). Therefore, remove the CPU_DYING
leg of the switch statement to avoid this problem.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/printk.c b/kernel/printk.c
index 66a2ea3..2d607f4 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1890,7 +1890,6 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self,
switch (action) {
case CPU_ONLINE:
case CPU_DEAD:
- case CPU_DYING:
case CPU_DOWN_FAILED:
case CPU_UP_CANCELED:
console_lock();
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] Fix scheduling-while-atomic problem in console_cpu_notify()
2012-10-16 4:35 ` Paul E. McKenney
@ 2012-10-16 5:31 ` Srivatsa S. Bhat
0 siblings, 0 replies; 3+ messages in thread
From: Srivatsa S. Bhat @ 2012-10-16 5:31 UTC (permalink / raw)
To: paulmck; +Cc: linux-kernel, cernekee, torbenh, torvalds, tglx
On 10/16/2012 10:05 AM, Paul E. McKenney wrote:
> On Mon, Oct 15, 2012 at 05:31:28PM -0700, Paul E. McKenney wrote:
>> The console_cpu_notify( function runs with interrupts disabled in
>> the CPU_DEAD case. It therefore cannot block, for example, as will
>> happen when it calls console_lock(). Therefore, remove the CPU_DEAD
>> leg of the switch statement to avoid this problem.
>>
>> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
>
> s/CPU_DEAD/CPU_DYING/
>
> Apparently it is a bad idea to compose and send a patch while in a
> C++ standards committee meeting where people are arguing about async
> futures... Fixed patch below.
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> printk: Fix scheduling-while-atomic problem in console_cpu_notify()
>
> The console_cpu_notify( function runs with interrupts disabled in
> the CPU_DYING case. It therefore cannot block, for example, as will
> happen when it calls console_lock(). Therefore, remove the CPU_DYING
> leg of the switch statement to avoid this problem.
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Regards,
Srivatsa S. Bhat
> diff --git a/kernel/printk.c b/kernel/printk.c
> index 66a2ea3..2d607f4 100644
> --- a/kernel/printk.c
> +++ b/kernel/printk.c
> @@ -1890,7 +1890,6 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self,
> switch (action) {
> case CPU_ONLINE:
> case CPU_DEAD:
> - case CPU_DYING:
> case CPU_DOWN_FAILED:
> case CPU_UP_CANCELED:
> console_lock();
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-10-16 0:31 [PATCH] Fix scheduling-while-atomic problem in console_cpu_notify() Paul E. McKenney
2012-10-16 4:35 ` Paul E. McKenney
2012-10-16 5:31 ` Srivatsa S. Bhat
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