On 2012年05月03日 10:15, Benjamin Herrenschmidt wrote:
> On Thu, 2012-05-03 at 09:53 +0800, Wang Sheng-Hui wrote:
>> local_paca->irq_happened may be changed asychronously.
>>
>> In my test env (IBM Power 9117-MMA), I installed the RHEL6.2 with the shipped
>> oprofile. Then I run into kernel v3.4-rc4, setup/start oprofile and start the
>> LTP test suite.
>>
>> In a short while, the system would crash. Seems that oprofile may change
>> the irq_happened.
>
> .../...
>
>> Use local var instead of local_paca->irq_happened directly in this function
>> here.
>>
>> Please check this patch. Any comments are welcome.
>
> It should not as __check_irq_replay() should always be called
> with interrupts hard disabled... Do you see any code path
> where that is not the case ?
This is the only case.
I have run LTP test suite on my system without oprofile over 24 hours
with 3.4-rc4 kernel.
Then I started oprofile, and the system crashed quickly.
I wonder if oprofile does some special changes with the running.
But I'm not familiar with the internal of oprofile.
I tried to change BUG_ON to WARN_ON, and got lots of warnning messages
in dmesg. So I changed it to local var here.
>
> Cheers,
> Ben.
>
>> Signed-off-by: Wang Sheng-Hui <shh...@gmail.com>
>> ---
>> arch/powerpc/kernel/irq.c | 46
>> +++++++++++++++++++++++++++++---------------
>> 1 files changed, 30 insertions(+), 16 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
>> index 5ec1b23..3d48b23 100644
>> --- a/arch/powerpc/kernel/irq.c
>> +++ b/arch/powerpc/kernel/irq.c
>> @@ -137,15 +137,17 @@ static inline notrace int
>> decrementer_check_overflow(void)
>> */
>> notrace unsigned int __check_irq_replay(void)
>> {
>> + unsigned int ret_val;
>> /*
>> * We use local_paca rather than get_paca() to avoid all
>> * the debug_smp_processor_id() business in this low level
>> * function
>> */
>> - unsigned char happened = local_paca->irq_happened;
>> + unsigned char happened, irq_happened;
>> + happened = irq_happened = local_paca->irq_happened;
>>
>> /* Clear bit 0 which we wouldn't clear otherwise */
>> - local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
>> + irq_happened &= ~PACA_IRQ_HARD_DIS;
>>
>> /*
>> * Force the delivery of pending soft-disabled interrupts on PS3.
>> @@ -161,33 +163,45 @@ notrace unsigned int __check_irq_replay(void)
>> * decrementer itself rather than the paca irq_happened field
>> * in case we also had a rollover while hard disabled
>> */
>> - local_paca->irq_happened &= ~PACA_IRQ_DEC;
>> - if (decrementer_check_overflow())
>> - return 0x900;
>> + irq_happened &= ~PACA_IRQ_DEC;
>> + if (decrementer_check_overflow()) {
>> + ret_val = 0x900;
>> + goto replay;
>> + }
>>
>> /* Finally check if an external interrupt happened */
>> - local_paca->irq_happened &= ~PACA_IRQ_EE;
>> - if (happened & PACA_IRQ_EE)
>> - return 0x500;
>> + irq_happened &= ~PACA_IRQ_EE;
>> + if (happened & PACA_IRQ_EE) {
>> + ret_val = 0x500;
>> + goto replay;
>> + }
>>
>> #ifdef CONFIG_PPC_BOOK3E
>> /* Finally check if an EPR external interrupt happened
>> * this bit is typically set if we need to handle another
>> * "edge" interrupt from within the MPIC "EPR" handler
>> */
>> - local_paca->irq_happened &= ~PACA_IRQ_EE_EDGE;
>> - if (happened & PACA_IRQ_EE_EDGE)
>> - return 0x500;
>> + irq_happened &= ~PACA_IRQ_EE_EDGE;
>> + if (happened & PACA_IRQ_EE_EDGE) {
>> + ret_val = 0x500;
>> + goto replay;
>> + }
>>
>> - local_paca->irq_happened &= ~PACA_IRQ_DBELL;
>> - if (happened & PACA_IRQ_DBELL)
>> - return 0x280;
>> + irq_happened &= ~PACA_IRQ_DBELL;
>> + if (happened & PACA_IRQ_DBELL) {
>> + ret_val = 0x280;
>> + goto replay;
>> + }
>> #endif /* CONFIG_PPC_BOOK3E */
>>
>> /* There should be nothing left ! */
>> - BUG_ON(local_paca->irq_happened != 0);
>> + BUG_ON(irq_happened != 0);
>> + ret_val = 0;
>>
>> - return 0;
>> +replay:
>> + local_paca->irq_happened = irq_happened;
>> +
>> + return ret_val;
>> }
>>
>> notrace void arch_local_irq_restore(unsigned long en)
>
>
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