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List: linux-gpio
Subject: [patch 3/5] genirq: Add mutex to irq desc to serialize request/free_irq()
From: Thomas Gleixner <tglx () linutronix ! de>
Date: 2017-06-29 21:33:37
Message-ID: 20170629214344.039220922 () linutronix ! de
[Download RAW message or body]
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>
---
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);
--
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