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-rw-r--r--include/linux/hardirq.h2
-rw-r--r--include/linux/interrupt.h37
-rw-r--r--include/linux/irq.h5
-rw-r--r--include/linux/irqreturn.h2
-rw-r--r--include/linux/sched.h5
-rw-r--r--kernel/exit.c2
-rw-r--r--kernel/irq/handle.c31
-rw-r--r--kernel/irq/manage.c192
8 files changed, 259 insertions, 17 deletions
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index f83288347dda..2dfaadbdb2ac 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -105,7 +105,7 @@
# define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
#endif
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
extern void synchronize_irq(unsigned int irq);
#else
# define synchronize_irq(irq) barrier()
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 0c9cb63e6895..6fc2b720c231 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -59,6 +59,16 @@
#define IRQF_NOBALANCING 0x00000800
#define IRQF_IRQPOLL 0x00001000
+/*
+ * Bits used by threaded handlers:
+ * IRQTF_RUNTHREAD - signals that the interrupt handler thread should run
+ * IRQTF_DIED - handler thread died
+ */
+enum {
+ IRQTF_RUNTHREAD,
+ IRQTF_DIED,
+};
+
typedef irqreturn_t (*irq_handler_t)(int, void *);
/**
@@ -71,6 +81,9 @@ typedef irqreturn_t (*irq_handler_t)(int, void *);
* @next: pointer to the next irqaction for shared interrupts
* @irq: interrupt number
* @dir: pointer to the proc/irq/NN/name entry
+ * @thread_fn: interupt handler function for threaded interrupts
+ * @thread: thread pointer for threaded interrupts
+ * @thread_flags: flags related to @thread
*/
struct irqaction {
irq_handler_t handler;
@@ -81,11 +94,31 @@ struct irqaction {
struct irqaction *next;
int irq;
struct proc_dir_entry *dir;
+ irq_handler_t thread_fn;
+ struct task_struct *thread;
+ unsigned long thread_flags;
};
extern irqreturn_t no_action(int cpl, void *dev_id);
-extern int __must_check request_irq(unsigned int, irq_handler_t handler,
- unsigned long, const char *, void *);
+
+extern int __must_check
+request_threaded_irq(unsigned int irq, irq_handler_t handler,
+ irq_handler_t thread_fn,
+ unsigned long flags, const char *name, void *dev);
+
+static inline int __must_check
+request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
+ const char *name, void *dev)
+{
+ return request_threaded_irq(irq, handler, NULL, flags, name, dev);
+}
+
+#ifdef CONFIG_GENERIC_HARDIRQS
+extern void exit_irq_thread(void);
+#else
+static inline void exit_irq_thread(void) { }
+#endif
+
extern void free_irq(unsigned int, void *);
struct device;
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 873e4ac11b81..8b1cf0630210 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -20,6 +20,7 @@
#include <linux/irqreturn.h>
#include <linux/irqnr.h>
#include <linux/errno.h>
+#include <linux/wait.h>
#include <asm/irq.h>
#include <asm/ptrace.h>
@@ -155,6 +156,8 @@ struct irq_2_iommu;
* @affinity: IRQ affinity on SMP
* @cpu: cpu index useful for balancing
* @pending_mask: pending rebalanced interrupts
+ * @threads_active: number of irqaction threads currently running
+ * @wait_for_threads: wait queue for sync_irq to wait for threaded handlers
* @dir: /proc/irq/ procfs entry
* @name: flow handler name for /proc/interrupts output
*/
@@ -186,6 +189,8 @@ struct irq_desc {
cpumask_var_t pending_mask;
#endif
#endif
+ atomic_t threads_active;
+ wait_queue_head_t wait_for_threads;
#ifdef CONFIG_PROC_FS
struct proc_dir_entry *dir;
#endif
diff --git a/include/linux/irqreturn.h b/include/linux/irqreturn.h
index c5584ca5b8c9..819acaaac3f5 100644
--- a/include/linux/irqreturn.h
+++ b/include/linux/irqreturn.h
@@ -5,10 +5,12 @@
* enum irqreturn
* @IRQ_NONE interrupt was not from this device
* @IRQ_HANDLED interrupt was handled by this device
+ * @IRQ_WAKE_THREAD handler requests to wake the handler thread
*/
enum irqreturn {
IRQ_NONE,
IRQ_HANDLED,
+ IRQ_WAKE_THREAD,
};
typedef enum irqreturn irqreturn_t;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 46d680643f89..38b77b0f56e5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1292,6 +1292,11 @@ struct task_struct {
/* Protection of (de-)allocation: mm, files, fs, tty, keyrings */
spinlock_t alloc_lock;
+#ifdef CONFIG_GENERIC_HARDIRQS
+ /* IRQ handler threads */
+ struct irqaction *irqaction;
+#endif
+
/* Protection of the PI data structures: */
spinlock_t pi_lock;
diff --git a/kernel/exit.c b/kernel/exit.c
index 167e1e3ad7c6..ca0b3488c4a9 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1037,6 +1037,8 @@ NORET_TYPE void do_exit(long code)
schedule();
}
+ exit_irq_thread();
+
exit_signals(tsk); /* sets PF_EXITING */
/*
* tsk->flags are checked in the futex code to protect against
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 9ebf77968871..fe8f45374e86 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -357,8 +357,37 @@ irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
do {
ret = action->handler(irq, action->dev_id);
- if (ret == IRQ_HANDLED)
+
+ switch (ret) {
+ case IRQ_WAKE_THREAD:
+ /*
+ * Wake up the handler thread for this
+ * action. In case the thread crashed and was
+ * killed we just pretend that we handled the
+ * interrupt. The hardirq handler above has
+ * disabled the device interrupt, so no irq
+ * storm is lurking.
+ */
+ if (likely(!test_bit(IRQTF_DIED,
+ &action->thread_flags))) {
+ set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
+ wake_up_process(action->thread);
+ }
+
+ /*
+ * Set it to handled so the spurious check
+ * does not trigger.
+ */
+ ret = IRQ_HANDLED;
+ /* Fall through to add to randomness */
+ case IRQ_HANDLED:
status |= action->flags;
+ break;
+
+ default:
+ break;
+ }
+
retval |= ret;
action = action->next;
} while (action);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 6458e99984c0..a4c1ab86cd25 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -8,16 +8,15 @@
*/
#include <linux/irq.h>
+#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
+#include <linux/sched.h>
#include "internals.h"
-#if defined(CONFIG_SMP) && defined(CONFIG_GENERIC_HARDIRQS)
-cpumask_var_t irq_default_affinity;
-
/**
* synchronize_irq - wait for pending IRQ handlers (on other CPUs)
* @irq: interrupt number to wait for
@@ -53,9 +52,18 @@ void synchronize_irq(unsigned int irq)
/* Oops, that failed? */
} while (status & IRQ_INPROGRESS);
+
+ /*
+ * We made sure that no hardirq handler is running. Now verify
+ * that no threaded handlers are active.
+ */
+ wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
}
EXPORT_SYMBOL(synchronize_irq);
+#ifdef CONFIG_SMP
+cpumask_var_t irq_default_affinity;
+
/**
* irq_can_set_affinity - Check if the affinity of a given irq can be set
* @irq: Interrupt to check
@@ -72,6 +80,18 @@ int irq_can_set_affinity(unsigned int irq)
return 1;
}
+static void
+irq_set_thread_affinity(struct irq_desc *desc, const struct cpumask *cpumask)
+{
+ struct irqaction *action = desc->action;
+
+ while (action) {
+ if (action->thread)
+ set_cpus_allowed_ptr(action->thread, cpumask);
+ action = action->next;
+ }
+}
+
/**
* irq_set_affinity - Set the irq affinity of a given irq
* @irq: Interrupt to set affinity
@@ -100,6 +120,7 @@ int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
cpumask_copy(desc->affinity, cpumask);
desc->chip->set_affinity(irq, cpumask);
#endif
+ irq_set_thread_affinity(desc, cpumask);
desc->status |= IRQ_AFFINITY_SET;
spin_unlock_irqrestore(&desc->lock, flags);
return 0;
@@ -150,6 +171,8 @@ int irq_select_affinity_usr(unsigned int irq)
spin_lock_irqsave(&desc->lock, flags);
ret = setup_affinity(irq, desc);
+ if (!ret)
+ irq_set_thread_affinity(desc, desc->affinity);
spin_unlock_irqrestore(&desc->lock, flags);
return ret;
@@ -384,6 +407,93 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
return ret;
}
+static inline int irq_thread_should_run(struct irqaction *action)
+{
+ return test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags);
+}
+
+static int irq_wait_for_interrupt(struct irqaction *action)
+{
+ while (!kthread_should_stop()) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (irq_thread_should_run(action)) {
+ __set_current_state(TASK_RUNNING);
+ return 0;
+ } else
+ schedule();
+ }
+ return -1;
+}
+
+/*
+ * Interrupt handler thread
+ */
+static int irq_thread(void *data)
+{
+ struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, };
+ struct irqaction *action = data;
+ struct irq_desc *desc = irq_to_desc(action->irq);
+ int wake;
+
+ sched_setscheduler(current, SCHED_FIFO, &param);
+ current->irqaction = action;
+
+ while (!irq_wait_for_interrupt(action)) {
+
+ atomic_inc(&desc->threads_active);
+
+ spin_lock_irq(&desc->lock);
+ if (unlikely(desc->status & IRQ_DISABLED)) {
+ /*
+ * CHECKME: We might need a dedicated
+ * IRQ_THREAD_PENDING flag here, which
+ * retriggers the thread in check_irq_resend()
+ * but AFAICT IRQ_PENDING should be fine as it
+ * retriggers the interrupt itself --- tglx
+ */
+ desc->status |= IRQ_PENDING;
+ spin_unlock_irq(&desc->lock);
+ } else {
+ spin_unlock_irq(&desc->lock);
+
+ action->thread_fn(action->irq, action->dev_id);
+ }
+
+ wake = atomic_dec_and_test(&desc->threads_active);
+
+ if (wake && waitqueue_active(&desc->wait_for_threads))
+ wake_up(&desc->wait_for_threads);
+ }
+
+ /*
+ * Clear irqaction. Otherwise exit_irq_thread() would make
+ * fuzz about an active irq thread going into nirvana.
+ */
+ current->irqaction = NULL;
+ return 0;
+}
+
+/*
+ * Called from do_exit()
+ */
+void exit_irq_thread(void)
+{
+ struct task_struct *tsk = current;
+
+ if (!tsk->irqaction)
+ return;
+
+ printk(KERN_ERR
+ "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
+ tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
+
+ /*
+ * Set the THREAD DIED flag to prevent further wakeups of the
+ * soon to be gone threaded handler.
+ */
+ set_bit(IRQTF_DIED, &tsk->irqaction->flags);
+}
+
/*
* Internal function to register an irqaction - typically used to
* allocate special interrupts that are part of the architecture.
@@ -420,6 +530,26 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
}
/*
+ * Threaded handler ?
+ */
+ if (new->thread_fn) {
+ struct task_struct *t;
+
+ t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
+ new->name);
+ if (IS_ERR(t))
+ return PTR_ERR(t);
+ /*
+ * We keep the reference to the task struct even if
+ * the thread dies to avoid that the interrupt code
+ * references an already freed task_struct.
+ */
+ get_task_struct(t);
+ new->thread = t;
+ wake_up_process(t);
+ }
+
+ /*
* The following block of code has to be executed atomically
*/
spin_lock_irqsave(&desc->lock, flags);
@@ -456,15 +586,15 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
if (!shared) {
irq_chip_set_defaults(desc->chip);
+ init_waitqueue_head(&desc->wait_for_threads);
+
/* Setup the type (level, edge polarity) if configured: */
if (new->flags & IRQF_TRIGGER_MASK) {
ret = __irq_set_trigger(desc, irq,
new->flags & IRQF_TRIGGER_MASK);
- if (ret) {
- spin_unlock_irqrestore(&desc->lock, flags);
- return ret;
- }
+ if (ret)
+ goto out_thread;
} else
compat_irq_chip_set_default_handler(desc);
#if defined(CONFIG_IRQ_PER_CPU)
@@ -532,8 +662,19 @@ mismatch:
dump_stack();
}
#endif
+ ret = -EBUSY;
+
+out_thread:
spin_unlock_irqrestore(&desc->lock, flags);
- return -EBUSY;
+ if (new->thread) {
+ struct task_struct *t = new->thread;
+
+ new->thread = NULL;
+ if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
+ kthread_stop(t);
+ put_task_struct(t);
+ }
+ return ret;
}
/**
@@ -559,6 +700,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
{
struct irq_desc *desc = irq_to_desc(irq);
struct irqaction *action, **action_ptr;
+ struct task_struct *irqthread;
unsigned long flags;
WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
@@ -605,6 +747,10 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
else
desc->chip->disable(irq);
}
+
+ irqthread = action->thread;
+ action->thread = NULL;
+
spin_unlock_irqrestore(&desc->lock, flags);
unregister_handler_proc(irq, action);
@@ -612,6 +758,12 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
/* Make sure it's not being used on another CPU: */
synchronize_irq(irq);
+ if (irqthread) {
+ if (!test_bit(IRQTF_DIED, &action->thread_flags))
+ kthread_stop(irqthread);
+ put_task_struct(irqthread);
+ }
+
#ifdef CONFIG_DEBUG_SHIRQ
/*
* It's a shared IRQ -- the driver ought to be prepared for an IRQ
@@ -664,9 +816,12 @@ void free_irq(unsigned int irq, void *dev_id)
EXPORT_SYMBOL(free_irq);
/**
- * request_irq - allocate an interrupt line
+ * request_threaded_irq - allocate an interrupt line
* @irq: Interrupt line to allocate
- * @handler: Function to be called when the IRQ occurs
+ * @handler: Function to be called when the IRQ occurs.
+ * Primary handler for threaded interrupts
+ * @thread_fn: Function called from the irq handler thread
+ * If NULL, no irq thread is created
* @irqflags: Interrupt type flags
* @devname: An ascii name for the claiming device
* @dev_id: A cookie passed back to the handler function
@@ -678,6 +833,15 @@ EXPORT_SYMBOL(free_irq);
* raises, you must take care both to initialise your hardware
* and to set up the interrupt handler in the right order.
*
+ * If you want to set up a threaded irq handler for your device
+ * then you need to supply @handler and @thread_fn. @handler ist
+ * still called in hard interrupt context and has to check
+ * whether the interrupt originates from the device. If yes it
+ * needs to disable the interrupt on the device and return
+ * IRQ_THREAD_WAKE which will wake up the handler thread and run
+ * @thread_fn. This split handler design is necessary to support
+ * shared interrupts.
+ *
* Dev_id must be globally unique. Normally the address of the
* device data structure is used as the cookie. Since the handler
* receives this value it makes sense to use it.
@@ -693,8 +857,9 @@ EXPORT_SYMBOL(free_irq);
* IRQF_TRIGGER_* Specify active edge(s) or level
*
*/
-int request_irq(unsigned int irq, irq_handler_t handler,
- unsigned long irqflags, const char *devname, void *dev_id)
+int request_threaded_irq(unsigned int irq, irq_handler_t handler,
+ irq_handler_t thread_fn, unsigned long irqflags,
+ const char *devname, void *dev_id)
{
struct irqaction *action;
struct irq_desc *desc;
@@ -742,6 +907,7 @@ int request_irq(unsigned int irq, irq_handler_t handler,
return -ENOMEM;
action->handler = handler;
+ action->thread_fn = thread_fn;
action->flags = irqflags;
action->name = devname;
action->dev_id = dev_id;
@@ -771,4 +937,4 @@ int request_irq(unsigned int irq, irq_handler_t handler,
#endif
return retval;
}
-EXPORT_SYMBOL(request_irq);
+EXPORT_SYMBOL(request_threaded_irq);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.