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: 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

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index d425a3a097227ed7e3e83c6fbfb8219cab55d9ed..3e90a094798d2955054db8f8bee381cb07dcfde9 100644 (file)
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -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;

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 948b50e78549f09a0dc3c5f00f97b7071656fa39..906a67e583912396aee646db4f05baaa1ff0a14e 100644 (file)
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -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);

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0934e02fa04ea81afd3c65ebbfdeff25d76ba2f8..0139908b8d53feb67ddfc346afd45a68553d522c 100644 (file)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -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 @@ out_unlock:
 
        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);