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 <[email protected]> --- include/linux/irqdesc.h | 3 +++ kernel/irq/irqdesc.c | 1 + kernel/irq/manage.c | 8 ++++++++ 3 files changed, 12 insertions(+) --- 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; --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -373,6 +373,7 @@ 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); --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1167,6 +1167,8 @@ static int 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 @@ static int 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 @@ static int 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(unsi 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(unsi } } + mutex_unlock(&desc->request_mutex); + irq_chip_pm_put(&desc->irq_data); module_put(desc->owner); kfree(action->secondary);
