Re: [GIT pull] irq updates for 4.13

[Thomas Gleixner]

Sebastian,

On Tue, 11 Jul 2017, Thomas Gleixner wrote:
> On Tue, 11 Jul 2017, Sebastian Reichel wrote:
> So this crashes in do_raw_spin_unlock_irqrestore() !?! I just have to
> wonder how the raw_spin_lock() succeeded. That does not make any sense.

can you please apply the patch below on top of 4.12? It's a backport
isolating the resource request changes.

Thanks,

	tglx

8<----------------------
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1198,6 +1198,18 @@ static int
 	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
 		new->flags &= ~IRQF_ONESHOT;
 
+	mutex_lock(&desc->request_mutex);
+	if (!desc->action) {
+		ret = irq_request_resources(desc);
+		if (ret) {
+			pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
+			       new->name, irq, desc->irq_data.chip->name);
+			goto out_mutex;
+		}
+	}
+
+	chip_bus_lock(desc);
+
 	/*
 	 * The following block of code has to be executed atomically
 	 */
@@ -1298,13 +1310,6 @@ static int
 	}
 
 	if (!shared) {
-		ret = irq_request_resources(desc);
-		if (ret) {
-			pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
-			       new->name, irq, desc->irq_data.chip->name);
-			goto out_mask;
-		}
-
 		init_waitqueue_head(&desc->wait_for_threads);
 
 		/* Setup the type (level, edge polarity) if configured: */
@@ -1312,10 +1317,8 @@ static int
 			ret = __irq_set_trigger(desc,
 						new->flags & IRQF_TRIGGER_MASK);
 
-			if (ret) {
-				irq_release_resources(desc);
+			if (ret)
 				goto out_mask;
-			}
 		}
 
 		desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
@@ -1373,6 +1376,8 @@ static int
 	}
 
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
+	chip_bus_sync_unlock(desc);
+	mutex_unlock(&desc->request_mutex);
 
 	/*
 	 * Strictly no need to wake it up, but hung_task complains
@@ -1402,6 +1407,13 @@ static int
 
 out_mask:
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
+	chip_bus_sync_unlock(desc);
+	if (!desc->action)
+		irq_release_resources(desc);
+
+out_mutex:
+	mutex_unlock(&desc->request_mutex);
+
 	free_cpumask_var(mask);
 
 out_thread:
@@ -1443,9 +1455,7 @@ int setup_irq(unsigned int irq, struct i
 	if (retval < 0)
 		return retval;
 
-	chip_bus_lock(desc);
 	retval = __setup_irq(irq, desc, act);
-	chip_bus_sync_unlock(desc);
 
 	if (retval)
 		irq_chip_pm_put(&desc->irq_data);
@@ -1469,6 +1479,7 @@ static struct irqaction *__free_irq(unsi
 	if (!desc)
 		return NULL;
 
+	mutex_lock(&desc->request_mutex);
 	chip_bus_lock(desc);
 	raw_spin_lock_irqsave(&desc->lock, flags);
 
@@ -1501,7 +1512,6 @@ static struct irqaction *__free_irq(unsi
 	if (!desc->action) {
 		irq_settings_clr_disable_unlazy(desc);
 		irq_shutdown(desc);
-		irq_release_resources(desc);
 	}
 
 #ifdef CONFIG_SMP
@@ -1543,6 +1553,11 @@ static struct irqaction *__free_irq(unsi
 		}
 	}
 
+	if (!desc->action)
+		irq_release_resources(desc);
+
+	mutex_unlock(&desc->request_mutex);
+
 	irq_chip_pm_put(&desc->irq_data);
 	module_put(desc->owner);
 	kfree(action->secondary);
@@ -1699,9 +1714,7 @@ int request_threaded_irq(unsigned int ir
 		return retval;
 	}
 
-	chip_bus_lock(desc);
 	retval = __setup_irq(irq, desc, action);
-	chip_bus_sync_unlock(desc);
 
 	if (retval) {
 		irq_chip_pm_put(&desc->irq_data);
@@ -1949,9 +1962,7 @@ int setup_percpu_irq(unsigned int irq, s
 	if (retval < 0)
 		return retval;
 
-	chip_bus_lock(desc);
 	retval = __setup_irq(irq, desc, act);
-	chip_bus_sync_unlock(desc);
 
 	if (retval)
 		irq_chip_pm_put(&desc->irq_data);
@@ -2005,9 +2016,7 @@ int request_percpu_irq(unsigned int irq,
 		return retval;
 	}
 
-	chip_bus_lock(desc);
 	retval = __setup_irq(irq, desc, action);
-	chip_bus_sync_unlock(desc);
 
 	if (retval) {
 		irq_chip_pm_put(&desc->irq_data);
--- 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
  * @name:		flow handler name for /proc/interrupts output
  */
@@ -92,6 +94,7 @@ struct irq_desc {
 	struct rcu_head		rcu;
 	struct kobject		kobj;
 #endif
+	struct mutex		request_mutex;
 	int			parent_irq;
 	struct module		*owner;
 	const char		*name;
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -359,6 +359,7 @@ static struct irq_desc *alloc_desc(int i
 
 	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);