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-rw-r--r--include/linux/interrupt.h2
-rw-r--r--include/linux/irqdesc.h2
-rw-r--r--kernel/irq/handle.c76
-rw-r--r--kernel/irq/manage.c54
4 files changed, 115 insertions, 19 deletions
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 8da6643e39a6..e116fef274cd 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -99,6 +99,7 @@ typedef irqreturn_t (*irq_handler_t)(int, void *);
* @thread_fn: interupt handler function for threaded interrupts
* @thread: thread pointer for threaded interrupts
* @thread_flags: flags related to @thread
+ * @thread_mask: bitmask for keeping track of @thread activity
*/
struct irqaction {
irq_handler_t handler;
@@ -109,6 +110,7 @@ struct irqaction {
irq_handler_t thread_fn;
struct task_struct *thread;
unsigned long thread_flags;
+ unsigned long thread_mask;
const char *name;
struct proc_dir_entry *dir;
} ____cacheline_internodealigned_in_smp;
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 2f87d6441302..9eb9cd313052 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -28,6 +28,7 @@ struct timer_rand_state;
* @lock: locking for SMP
* @affinity_notify: context for notification of affinity changes
* @pending_mask: pending rebalanced interrupts
+ * @threads_oneshot: bitfield to handle shared oneshot threads
* @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
@@ -86,6 +87,7 @@ struct irq_desc {
cpumask_var_t pending_mask;
#endif
#endif
+ unsigned long threads_oneshot;
atomic_t threads_active;
wait_queue_head_t wait_for_threads;
#ifdef CONFIG_PROC_FS
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index b110c835e070..517561fc7317 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -51,6 +51,68 @@ static void warn_no_thread(unsigned int irq, struct irqaction *action)
"but no thread function available.", irq, action->name);
}
+static void irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
+{
+ /*
+ * 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 has disabled the
+ * device interrupt, so no irq storm is lurking. If the
+ * RUNTHREAD bit is already set, nothing to do.
+ */
+ if (test_bit(IRQTF_DIED, &action->thread_flags) ||
+ test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags))
+ return;
+
+ /*
+ * It's safe to OR the mask lockless here. We have only two
+ * places which write to threads_oneshot: This code and the
+ * irq thread.
+ *
+ * This code is the hard irq context and can never run on two
+ * cpus in parallel. If it ever does we have more serious
+ * problems than this bitmask.
+ *
+ * The irq threads of this irq which clear their "running" bit
+ * in threads_oneshot are serialized via desc->lock against
+ * each other and they are serialized against this code by
+ * IRQS_INPROGRESS.
+ *
+ * Hard irq handler:
+ *
+ * spin_lock(desc->lock);
+ * desc->state |= IRQS_INPROGRESS;
+ * spin_unlock(desc->lock);
+ * set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
+ * desc->threads_oneshot |= mask;
+ * spin_lock(desc->lock);
+ * desc->state &= ~IRQS_INPROGRESS;
+ * spin_unlock(desc->lock);
+ *
+ * irq thread:
+ *
+ * again:
+ * spin_lock(desc->lock);
+ * if (desc->state & IRQS_INPROGRESS) {
+ * spin_unlock(desc->lock);
+ * while(desc->state & IRQS_INPROGRESS)
+ * cpu_relax();
+ * goto again;
+ * }
+ * if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
+ * desc->threads_oneshot &= ~mask;
+ * spin_unlock(desc->lock);
+ *
+ * So either the thread waits for us to clear IRQS_INPROGRESS
+ * or we are waiting in the flow handler for desc->lock to be
+ * released before we reach this point. The thread also checks
+ * IRQTF_RUNTHREAD under desc->lock. If set it leaves
+ * threads_oneshot untouched and runs the thread another time.
+ */
+ desc->threads_oneshot |= action->thread_mask;
+ wake_up_process(action->thread);
+}
+
irqreturn_t
handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action)
{
@@ -85,19 +147,7 @@ handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action)
break;
}
- /*
- * 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);
- }
+ irq_wake_thread(desc, action);
/* Fall through to add to randomness */
case IRQ_HANDLED:
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 01f8a9519e63..2301de19ac7d 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -617,8 +617,11 @@ static int irq_wait_for_interrupt(struct irqaction *action)
* handler finished. unmask if the interrupt has not been disabled and
* is marked MASKED.
*/
-static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
+static void irq_finalize_oneshot(struct irq_desc *desc,
+ struct irqaction *action, bool force)
{
+ if (!(desc->istate & IRQS_ONESHOT))
+ return;
again:
chip_bus_lock(desc);
raw_spin_lock_irq(&desc->lock);
@@ -631,6 +634,11 @@ again:
* on the other CPU. If we unmask the irq line then the
* interrupt can come in again and masks the line, leaves due
* to IRQS_INPROGRESS and the irq line is masked forever.
+ *
+ * This also serializes the state of shared oneshot handlers
+ * versus "desc->threads_onehsot |= action->thread_mask;" in
+ * irq_wake_thread(). See the comment there which explains the
+ * serialization.
*/
if (unlikely(desc->istate & IRQS_INPROGRESS)) {
raw_spin_unlock_irq(&desc->lock);
@@ -639,11 +647,23 @@ again:
goto again;
}
- if (!(desc->istate & IRQS_DISABLED) && (desc->istate & IRQS_MASKED)) {
+ /*
+ * Now check again, whether the thread should run. Otherwise
+ * we would clear the threads_oneshot bit of this thread which
+ * was just set.
+ */
+ if (!force && test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
+ goto out_unlock;
+
+ desc->threads_oneshot &= ~action->thread_mask;
+
+ if (!desc->threads_oneshot && !(desc->istate & IRQS_DISABLED) &&
+ (desc->istate & IRQS_MASKED)) {
irq_compat_clr_masked(desc);
desc->istate &= ~IRQS_MASKED;
desc->irq_data.chip->irq_unmask(&desc->irq_data);
}
+out_unlock:
raw_spin_unlock_irq(&desc->lock);
chip_bus_sync_unlock(desc);
}
@@ -691,7 +711,7 @@ static int irq_thread(void *data)
};
struct irqaction *action = data;
struct irq_desc *desc = irq_to_desc(action->irq);
- int wake, oneshot = desc->istate & IRQS_ONESHOT;
+ int wake;
sched_setscheduler(current, SCHED_FIFO, &param);
current->irqaction = action;
@@ -719,8 +739,7 @@ static int irq_thread(void *data)
action->thread_fn(action->irq, action->dev_id);
- if (oneshot)
- irq_finalize_oneshot(action->irq, desc);
+ irq_finalize_oneshot(desc, action, false);
}
wake = atomic_dec_and_test(&desc->threads_active);
@@ -729,6 +748,9 @@ static int irq_thread(void *data)
wake_up(&desc->wait_for_threads);
}
+ /* Prevent a stale desc->threads_oneshot */
+ irq_finalize_oneshot(desc, action, true);
+
/*
* Clear irqaction. Otherwise exit_irq_thread() would make
* fuzz about an active irq thread going into nirvana.
@@ -743,6 +765,7 @@ static int irq_thread(void *data)
void exit_irq_thread(void)
{
struct task_struct *tsk = current;
+ struct irq_desc *desc;
if (!tsk->irqaction)
return;
@@ -751,6 +774,14 @@ void exit_irq_thread(void)
"exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
+ desc = irq_to_desc(tsk->irqaction->irq);
+
+ /*
+ * Prevent a stale desc->threads_oneshot. Must be called
+ * before setting the IRQTF_DIED flag.
+ */
+ irq_finalize_oneshot(desc, tsk->irqaction, true);
+
/*
* Set the THREAD DIED flag to prevent further wakeups of the
* soon to be gone threaded handler.
@@ -767,7 +798,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
struct irqaction *old, **old_ptr;
const char *old_name = NULL;
- unsigned long flags;
+ unsigned long flags, thread_mask = 0;
int ret, nested, shared = 0;
cpumask_var_t mask;
@@ -865,12 +896,23 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
/* add new interrupt at end of irq queue */
do {
+ thread_mask |= old->thread_mask;
old_ptr = &old->next;
old = *old_ptr;
} while (old);
shared = 1;
}
+ /*
+ * Setup the thread mask for this irqaction. Unlikely to have
+ * 32 resp 64 irqs sharing one line, but who knows.
+ */
+ if (new->flags & IRQF_ONESHOT && thread_mask == ~0UL) {
+ ret = -EBUSY;
+ goto out_mask;
+ }
+ new->thread_mask = 1 << ffz(thread_mask);
+
if (!shared) {
irq_chip_set_defaults(desc->irq_data.chip);
generated by cgit v1.2.3 (git 2.0.4) at 2024-05-12 04:53:37 +0000