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Commit 9114014c authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

genirq: Add mutex to irq desc to serialize request/free_irq() 



The irq_request/release_resources() callbacks ar currently invoked under
desc->lock with interrupts disabled. This is a source of problems on RT and
conceptually not required.

Add a seperate mutex to struct irq_desc which allows to serialize
request/free_irq(), which can be used to move the resource functions out of
the desc->lock held region.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Cc: Heiko Stuebner <heiko@sntech.de>
Cc: Julia Cartwright <julia@ni.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Doug Anderson <dianders@chromium.org>
Cc: linux-rockchip@lists.infradead.org
Cc: John Keeping <john@metanate.com>
Cc: linux-gpio@vger.kernel.org
Link: http://lkml.kernel.org/r/20170629214344.039220922@linutronix.de
parent 3a90795e

include/linux/irqdesc.h

+3 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 


#include <linux/rcupdate.h>

#include <linux/kobject.h>

#include <linux/mutex.h>



/*

 * Core internal functions to deal with irq descriptors
@@ -45,6 +46,7 @@ struct pt_regs; 
 *			IRQF_FORCE_RESUME set

 * @rcu:		rcu head for delayed free

 * @kobj:		kobject used to represent this struct in sysfs

 * @request_mutex:	mutex to protect request/free before locking desc->lock

 * @dir:		/proc/irq/ procfs entry

 * @debugfs_file:	dentry for the debugfs file

 * @name:		flow handler name for /proc/interrupts output
@@ -96,6 +98,7 @@ struct irq_desc { 
	struct rcu_head		rcu;

	struct kobject		kobj;

#endif

	struct mutex		request_mutex;

	int			parent_irq;

	struct module		*owner;

	const char		*name;

kernel/irq/irqdesc.c

+1 −0
Original line number Diff line number Diff line
@@ -373,6 +373,7 @@ static struct irq_desc *alloc_desc(int irq, int node, unsigned int flags, 


	raw_spin_lock_init(&desc->lock);

	lockdep_set_class(&desc->lock, &irq_desc_lock_class);

	mutex_init(&desc->request_mutex);

	init_rcu_head(&desc->rcu);



	desc_set_defaults(irq, desc, node, affinity, owner);

kernel/irq/manage.c

+8 −0
Original line number Diff line number Diff line
@@ -1167,6 +1167,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) 
	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)

		new->flags &= ~IRQF_ONESHOT;



	mutex_lock(&desc->request_mutex);



	chip_bus_lock(desc);



	/*
@@ -1350,6 +1352,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) 


	raw_spin_unlock_irqrestore(&desc->lock, flags);

	chip_bus_sync_unlock(desc);

	mutex_unlock(&desc->request_mutex);



	irq_setup_timings(desc, new);
@@ -1383,6 +1386,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) 


	chip_bus_sync_unlock(desc);



	mutex_unlock(&desc->request_mutex);



out_thread:

	if (new->thread) {

		struct task_struct *t = new->thread;
@@ -1446,6 +1451,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) 
	if (!desc)

		return NULL;



	mutex_lock(&desc->request_mutex);

	chip_bus_lock(desc);

	raw_spin_lock_irqsave(&desc->lock, flags);
@@ -1521,6 +1527,8 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) 
		}

	}



	mutex_unlock(&desc->request_mutex);



	irq_chip_pm_put(&desc->irq_data);

	module_put(desc->owner);

	kfree(action->secondary);