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Commit 76ba59f8 authored by Marc Zyngier's avatar Marc Zyngier Committed by Jason Cooper
Browse files

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:

<quote>
===============================
[ 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: [<ffffffc00010206c>]
irq_find_mapping+0x4c/0x198
</quote>

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: default avatarVladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1409047421-27649-2-git-send-email-marc.zyngier@arm.com


Signed-off-by: default avatarJason Cooper <jason@lakedaemon.net>
parent 7d1311b9

include/linux/irqdesc.h

+19 −0
Original line number Diff line number Diff line
@@ -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)

{

kernel/irq/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -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

kernel/irq/irqdesc.c

+42 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/kernel_stat.h>

#include <linux/radix-tree.h>

#include <linux/bitmap.h>

#include <linux/irqdomain.h>



#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 */



/**