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.
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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.
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hosted by The Linux Foundation
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[PATCH v2 01/26] genirq: add irq_domain-aware core IRQ handler
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
As this issue is fairly widespread and involves at least three
different architectures, a possible solution is to add a new
handle_domain_irq entry point into the generic IRQ code that
the interrupt controller code can call.
This new function takes an irq_domain, and calls into irq_find_domain
inside the irq_{enter,exit} block. An additional "lookup" parameter is
used to allow non-domain architecture code to be replaced by this as well.
Interrupt controllers can then be updated to use the new mechanism.
This code is sitting behind a new CONFIG_HANDLE_DOMAIN_IRQ, as not all
architectures implement set_irq_regs (yes, mn10300, I'm looking at you...).
Reported-by: Vladimir Murzin
Signed-off-by: Marc Zyngier
---
include/linux/irqdesc.h | 19 +++
kernel/irq/Kconfig | 3 +++
kernel/irq/irqdesc.c| 42 ++
3 files changed, 64 insertions(+)
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 472c021..ff24667 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -12,6 +12,8 @@ struct irq_affinity_notify;
struct proc_dir_entry;
struct module;
struct irq_desc;
+struct irq_domain;
+struct pt_regs;
/**
* struct irq_desc - interrupt descriptor
@@ -118,6 +120,23 @@ static inline void generic_handle_irq_desc(unsigned int
irq, struct irq_desc *de
int generic_handle_irq(unsigned int irq);
+#ifdef CONFIG_HANDLE_DOMAIN_IRQ
+/*
+ * Convert a HW interrupt number to a logical one using a IRQ domain,
+ * and handle the result interrupt number. Return -EINVAL if
+ * conversion failed. Providing a NULL domain indicates that the
+ * conversion has already been done.
+ */
+int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
+ bool lookup, struct pt_regs *regs);
+
+static inline int handle_domain_irq(struct irq_domain *domain,
+ unsigned int hwirq, struct pt_regs *regs)
+{
+ return __handle_domain_irq(domain, hwirq, true, regs);
+}
+#endif
+
/* Test to see if a driver has successfully requested an irq */
static inline int irq_has_action(unsigned int irq)
{
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index d269cec..225086b 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -55,6 +55,9 @@ config GENERIC_IRQ_CHIP
config IRQ_DOMAIN
bool
+config HANDLE_DOMAIN_IRQ
+ bool
+
config IRQ_DOMAIN_DEBUG
bool "Expose hardware/virtual IRQ mapping via debugfs"
depends on IRQ_DOMAIN && DEBUG_FS
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 1487a12..a1782f8 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -14,6 +14,7 @@
#include
#include
#include
+#include
#include "internals.h"
@@ -336,6 +337,47 @@ int generic_handle_irq(unsigned int irq)
}
EXPORT_SYMBOL_GPL(generic_handle_irq);
+#ifdef CONFIG_HANDLE_DOMAIN_IRQ
+/**
+ * __handle_domain_irq - Invoke the handler for a HW irq belonging to a domain
+ * @domain:The domain where to perform the lookup
+ * @hwirq: The HW irq number to convert to a logical one
+ * @lookup:Whether to perform the domain lookup or not
+ * @regs: Register file coming from the low-level handling code
+ *
+ * Returns:0 on success, or -EINVAL if conversion has failed
+ */
+int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
+ bool lookup, struct pt_regs *regs)
+{
+ struct pt_regs *old_regs = set_irq_regs(regs);
+ unsigned int irq = hwirq;
+ int ret = 0;
+
+ irq_enter();
+
+#ifdef CONFIG_IRQ_DOMAIN
+ if (lookup)
+ irq = irq_find_mapping(domain, hwirq);
+#endif
+
+ /*
+* Some hardware gives randomly wrong interrupts. Rather
+* than crashing, do something sensible.
+*/
+ if (unlikely(!irq || irq >= nr_irqs)) {
+ ack_bad_irq(irq);
+ ret = -EINVAL;
+ } else {
+ generic_handle_irq(irq);
+ }
+
+ irq_exit();
+ set_irq_regs(old_regs);
+ return ret;
+}
+#endif
+
/* Dynamic interrupt handling */
/**
--
2.0.4
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