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

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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: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc 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
This commit is contained in:
Thomas Gleixner 2017-06-29 23:33:37 +02:00
parent 3a90795e1e
commit 9114014cf4
3 changed files with 12 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/irqdesc.h
View File

@ -3,6 +3,7 @@
#include <linux/rcupdate.h> #include <linux/rcupdate.h>
#include <linux/kobject.h> #include <linux/kobject.h>
#include <linux/mutex.h>
/* /*
* Core internal functions to deal with irq descriptors * Core internal functions to deal with irq descriptors
@ -45,6 +46,7 @@ struct pt_regs;
* IRQF_FORCE_RESUME set * IRQF_FORCE_RESUME set
* @rcu: rcu head for delayed free * @rcu: rcu head for delayed free
* @kobj: kobject used to represent this struct in sysfs * @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 * @dir: /proc/irq/ procfs entry
* @debugfs_file: dentry for the debugfs file * @debugfs_file: dentry for the debugfs file
* @name: flow handler name for /proc/interrupts output * @name: flow handler name for /proc/interrupts output
@ -96,6 +98,7 @@ struct irq_desc {
struct rcu_head rcu; struct rcu_head rcu;
struct kobject kobj; struct kobject kobj;
#endif #endif
struct mutex request_mutex;
int parent_irq; int parent_irq;
struct module *owner; struct module *owner;
const char *name; const char *name;

1
kernel/irq/irqdesc.c
View File

@ -373,6 +373,7 @@ static struct irq_desc *alloc_desc(int irq, int node, unsigned int flags,
raw_spin_lock_init(&desc->lock); raw_spin_lock_init(&desc->lock);
lockdep_set_class(&desc->lock, &irq_desc_lock_class); lockdep_set_class(&desc->lock, &irq_desc_lock_class);
mutex_init(&desc->request_mutex);
init_rcu_head(&desc->rcu); init_rcu_head(&desc->rcu);
desc_set_defaults(irq, desc, node, affinity, owner); desc_set_defaults(irq, desc, node, affinity, owner);

8
kernel/irq/manage.c
View File

@ -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) if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
new->flags &= ~IRQF_ONESHOT; new->flags &= ~IRQF_ONESHOT;
mutex_lock(&desc->request_mutex);
chip_bus_lock(desc); 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); raw_spin_unlock_irqrestore(&desc->lock, flags);
chip_bus_sync_unlock(desc); chip_bus_sync_unlock(desc);
mutex_unlock(&desc->request_mutex);
irq_setup_timings(desc, new); irq_setup_timings(desc, new);
@ -1383,6 +1386,8 @@ out_unlock:
chip_bus_sync_unlock(desc); chip_bus_sync_unlock(desc);
mutex_unlock(&desc->request_mutex);
out_thread: out_thread:
if (new->thread) { if (new->thread) {
struct task_struct *t = 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) if (!desc)
return NULL; return NULL;
mutex_lock(&desc->request_mutex);
chip_bus_lock(desc); chip_bus_lock(desc);
raw_spin_lock_irqsave(&desc->lock, flags); 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); irq_chip_pm_put(&desc->irq_data);
module_put(desc->owner); module_put(desc->owner);
kfree(action->secondary); kfree(action->secondary);