Re: [PATCH v2 01/26] genirq: add irq_domain-aware core IRQ handler
On Tue, Aug 26, 2014 at 11:46:38AM -0700, Stephen Boyd wrote: > Ah ok. This is the multi-irq handler case? Has this been broken since > v3.2 at least for the gic users? Now that we call irq_enter()/irq_exit() > a lot more code runs, including things like updating jiffies when > interrupts arrive and invoking softirq? Do we only call irq_exit() on > the IPI path otherwise? > > Are there any plans to send this back to stable trees? Not calling > irq_enter()/irq_exit() when we get an interrupt seems like a big problem. gic_handle_irq() calls handle_IRQ() which has the irq_enter()..irq_exit() wrappers. If we didn't have irq_exit(), then softirq's would be totally broken on all gic-based platforms. -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v2 01/26] genirq: add irq_domain-aware core IRQ handler
On 08/26/14 11:46, Stephen Boyd wrote: > On 08/26/14 11:07, Marc Zyngier wrote: >> Digging into my email, one of the traces looked like this: >> >> stack backtrace: >> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.16.0-rc1+ #135 >> Call trace: >> [] dump_backtrace+0x0/0x12c >> [] show_stack+0x10/0x1c >> [] dump_stack+0x74/0xc4 >> [] lockdep_rcu_suspicious+0xe8/0x124 >> [] irq_find_mapping+0x16c/0x198 >> [] gic_handle_irq+0x38/0xcc >> >> Most drivers call irq_find_mapping outside of irq_enter()/irq_exit(), as >> this is in handle_IRQ(). >> > Ah ok. This is the multi-irq handler case? Has this been broken since > v3.2 at least for the gic users? Now that we call irq_enter()/irq_exit() > a lot more code runs, including things like updating jiffies when > interrupts arrive and invoking softirq? Do we only call irq_exit() on > the IPI path otherwise? > > Are there any plans to send this back to stable trees? Not calling > irq_enter()/irq_exit() when we get an interrupt seems like a big problem. > Hmm I see we still call handle_IRQ eventually. So it's not as bad as I first thought. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v2 01/26] genirq: add irq_domain-aware core IRQ handler
On 08/26/14 11:07, Marc Zyngier wrote: > Digging into my email, one of the traces looked like this: > > stack backtrace: > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.16.0-rc1+ #135 > Call trace: > [] dump_backtrace+0x0/0x12c > [] show_stack+0x10/0x1c > [] dump_stack+0x74/0xc4 > [] lockdep_rcu_suspicious+0xe8/0x124 > [] irq_find_mapping+0x16c/0x198 > [] gic_handle_irq+0x38/0xcc > > Most drivers call irq_find_mapping outside of irq_enter()/irq_exit(), as > this is in handle_IRQ(). > Ah ok. This is the multi-irq handler case? Has this been broken since v3.2 at least for the gic users? Now that we call irq_enter()/irq_exit() a lot more code runs, including things like updating jiffies when interrupts arrive and invoking softirq? Do we only call irq_exit() on the IPI path otherwise? Are there any plans to send this back to stable trees? Not calling irq_enter()/irq_exit() when we get an interrupt seems like a big problem. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v2 01/26] genirq: add irq_domain-aware core IRQ handler
On 26/08/14 18:42, Stephen Boyd wrote:
> On 08/26/14 03:03, Marc Zyngier wrote:
>> Calling irq_find_mapping from outside a irq_{enter,exit} section is
>> unsafe and produces ugly messages if CONFIG_PROVE_RCU is enabled:
>> If coming from the idle state, the rcu_read_lock call in irq_find_mapping
>> will generate an unpleasant warning:
>>
>>
>> ===
>> [ INFO: suspicious RCU usage. ]
>> 3.16.0-rc1+ #135 Not tainted
>> ---
>> include/linux/rcupdate.h:871 rcu_read_lock() used illegally while idle!
>>
>> other info that might help us debug this:
>>
>> RCU used illegally from idle CPU!
>> rcu_scheduler_active = 1, debug_locks = 0
>> RCU used illegally from extended quiescent state!
>> 1 lock held by swapper/0/0:
>> #0: (rcu_read_lock){..}, at: []
>> irq_find_mapping+0x4c/0x198
>
> Do you have the whole stacktrace? I don't see where this is called
> outside of irq_enter() from within the idle loop, but maybe I missed
> something.
>
Hi Stephen,
Digging into my email, one of the traces looked like this:
stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.16.0-rc1+ #135
Call trace:
[] dump_backtrace+0x0/0x12c
[] show_stack+0x10/0x1c
[] dump_stack+0x74/0xc4
[] lockdep_rcu_suspicious+0xe8/0x124
[] irq_find_mapping+0x16c/0x198
[] gic_handle_irq+0x38/0xcc
Most drivers call irq_find_mapping outside of irq_enter()/irq_exit(), as
this is in handle_IRQ().
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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Re: [PATCH v2 01/26] genirq: add irq_domain-aware core IRQ handler
On 08/26/14 03:03, Marc Zyngier wrote:
> Calling irq_find_mapping from outside a irq_{enter,exit} section is
> unsafe and produces ugly messages if CONFIG_PROVE_RCU is enabled:
> If coming from the idle state, the rcu_read_lock call in irq_find_mapping
> will generate an unpleasant warning:
>
>
> ===
> [ INFO: suspicious RCU usage. ]
> 3.16.0-rc1+ #135 Not tainted
> ---
> include/linux/rcupdate.h:871 rcu_read_lock() used illegally while idle!
>
> other info that might help us debug this:
>
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 0
> RCU used illegally from extended quiescent state!
> 1 lock held by swapper/0/0:
> #0: (rcu_read_lock){..}, at: []
> irq_find_mapping+0x4c/0x198
Do you have the whole stacktrace? I don't see where this is called
outside of irq_enter() from within the idle loop, but maybe I missed
something.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation
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