diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 89835a4766a68..cac6cf9a588cd 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2436,6 +2436,10 @@ and is between 256 and 4096 characters. It is defined in the file
<deci-seconds>: poll all this frequency
0: no polling (default)
+ threadirqs [KNL]
+ Force threading of all interrupt handlers except those
+ marked explicitely IRQF_NO_THREAD.
+
topology= [S390]
Format: {off | on}
Specify if the kernel should make use of the cpu
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 0fc3eb9397b48..f8a8af108e0cd 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -383,6 +383,13 @@ static inline int disable_irq_wake(unsigned int irq)
}
#endif /* CONFIG_GENERIC_HARDIRQS */
+
+#ifdef CONFIG_IRQ_FORCED_THREADING
+extern bool force_irqthreads;
+#else
+#define force_irqthreads (0)
+#endif
+
#ifndef __ARCH_SET_SOFTIRQ_PENDING
#define set_softirq_pending(x) (local_softirq_pending() = (x))
#define or_softirq_pending(x) (local_softirq_pending() |= (x))
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index 355b8c7957f5e..144db9dcfcde9 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -38,6 +38,9 @@ config HARDIRQS_SW_RESEND
config IRQ_PREFLOW_FASTEOI
bool
+config IRQ_FORCED_THREADING
+ bool
+
config SPARSE_IRQ
bool "Support sparse irq numbering"
depends on HAVE_SPARSE_IRQ
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 935bec4bfa874..6c6ec9a490274 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -27,12 +27,14 @@ extern int noirqdebug;
* IRQTF_DIED - handler thread died
* IRQTF_WARNED - warning "IRQ_WAKE_THREAD w/o thread_fn" has been printed
* IRQTF_AFFINITY - irq thread is requested to adjust affinity
+ * IRQTF_FORCED_THREAD - irq action is force threaded
*/
enum {
IRQTF_RUNTHREAD,
IRQTF_DIED,
IRQTF_WARNED,
IRQTF_AFFINITY,
+ IRQTF_FORCED_THREAD,
};
/*
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 58c861367300d..acd599a43bfb5 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -17,6 +17,17 @@
#include "internals.h"
+#ifdef CONFIG_IRQ_FORCED_THREADING
+__read_mostly bool force_irqthreads;
+
+static int __init setup_forced_irqthreads(char *arg)
+{
+ force_irqthreads = true;
+ return 0;
+}
+early_param("threadirqs", setup_forced_irqthreads);
+#endif
+
/**
* synchronize_irq - wait for pending IRQ handlers (on other CPUs)
* @irq: interrupt number to wait for
@@ -701,6 +712,32 @@ static inline void
irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
#endif
+/*
+ * Interrupts which are not explicitely requested as threaded
+ * interrupts rely on the implicit bh/preempt disable of the hard irq
+ * context. So we need to disable bh here to avoid deadlocks and other
+ * side effects.
+ */
+static void
+irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
+{
+ local_bh_disable();
+ action->thread_fn(action->irq, action->dev_id);
+ irq_finalize_oneshot(desc, action, false);
+ local_bh_enable();
+}
+
+/*
+ * Interrupts explicitely requested as threaded interupts want to be
+ * preemtible - many of them need to sleep and wait for slow busses to
+ * complete.
+ */
+static void irq_thread_fn(struct irq_desc *desc, struct irqaction *action)
+{
+ action->thread_fn(action->irq, action->dev_id);
+ irq_finalize_oneshot(desc, action, false);
+}
+
/*
* Interrupt handler thread
*/
@@ -711,8 +748,15 @@ static int irq_thread(void *data)
};
struct irqaction *action = data;
struct irq_desc *desc = irq_to_desc(action->irq);
+ void (*handler_fn)(struct irq_desc *desc, struct irqaction *action);
int wake;
+ if (force_irqthreads & test_bit(IRQTF_FORCED_THREAD,
+ &action->thread_flags))
+ handler_fn = irq_forced_thread_fn;
+ else
+ handler_fn = irq_thread_fn;
+
sched_setscheduler(current, SCHED_FIFO, ¶m);
current->irqaction = action;
@@ -736,10 +780,7 @@ static int irq_thread(void *data)
raw_spin_unlock_irq(&desc->lock);
} else {
raw_spin_unlock_irq(&desc->lock);
-
- action->thread_fn(action->irq, action->dev_id);
-
- irq_finalize_oneshot(desc, action, false);
+ handler_fn(desc, action);
}
wake = atomic_dec_and_test(&desc->threads_active);
@@ -789,6 +830,22 @@ void exit_irq_thread(void)
set_bit(IRQTF_DIED, &tsk->irqaction->flags);
}
+static void irq_setup_forced_threading(struct irqaction *new)
+{
+ if (!force_irqthreads)
+ return;
+ if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
+ return;
+
+ new->flags |= IRQF_ONESHOT;
+
+ if (!new->thread_fn) {
+ set_bit(IRQTF_FORCED_THREAD, &new->thread_flags);
+ new->thread_fn = new->handler;
+ new->handler = irq_default_primary_handler;
+ }
+}
+
/*
* Internal function to register an irqaction - typically used to
* allocate special interrupts that are part of the architecture.
@@ -838,6 +895,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
* dummy function which warns when called.
*/
new->handler = irq_nested_primary_handler;
+ } else {
+ irq_setup_forced_threading(new);
}
/*
diff --git a/kernel/softirq.c b/kernel/softirq.c
index c0490464e92f0..a33fb29112482 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -311,9 +311,21 @@ void irq_enter(void)
}
#ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
-# define invoke_softirq() __do_softirq()
+static inline void invoke_softirq(void)
+{
+ if (!force_irqthreads)
+ __do_softirq();
+ else
+ wakeup_softirqd();
+}
#else
-# define invoke_softirq() do_softirq()
+static inline void invoke_softirq(void)
+{
+ if (!force_irqthreads)
+ do_softirq();
+ else
+ wakeup_softirqd();
+}
#endif
/*