[PATCH, v4] irq / PM: Fix IRQF_NO_SUSPEND problem with shared interrupts

Rafael J. Wysocki
2014-07-29T07:09:46Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Since __disable_irq() only checks IRQF_NO_SUSPEND for the first
irqaction in a given irq_desc, that value of that bit for the
first irqaction affects all of the other irqactions sharing the
interrupt with it. This is problematic in two cases.

First, if IRQF_NO_SUSPEND is set in the first irqaction and unset
in at least one of the other irqactions sharing the same interrupt,
the interrupt handlers in the other irqactions with IRQF_NO_SUSPEND
unset will be invoked after suspend_device_irqs() has returned even
though they are not supposed to. That shouldn't be a problem if
those interrupt handlers are implemented correctly and the
corresponding devices are properly suspended, but it may lead to
functional issues otherwise.

Second, if IRQF_NO_SUSPEND is unset in the first irqaction and set
in at least one of the other irqactions sharing the same interrupt,
the interrupt handlers in the other irqactions with IRQF_NO_SUSPEND
set will not be invoked after suspend_device_irqs() has returned, but
they are supposed to be invoked then. That may be a problem if the
corresponding devices are wakeup devices or if their interrupts have
to be properly handled during system suspend/resume too for other
reasons, which is the case for timer interrupts or the ACPI SCI for
example.

To address this, modify the handling of IRQF_NO_SUSPEND by
suspend_device_irqs() and resume_device_irqs() and make
note_interrupt() handle suspended interrupts.

First of all, make suspend_device_irqs() check IRQF_NO_SUSPEND for
all irqactions sharing the same irq_desc and avoid disabling the IRQ
if at least one of them has IRQF_NO_SUSPEND set. If that flag is
also unset for at least one irqaction in the given irq_desc, however,
suspend_device_irqs() will move the irqactions with IRQF_NO_SUSPEND
unset over to a list of "suspended actions" whose interrupt handlers
won't be invoked going forward.

Second, modify note_interrupt() to disable misbehaving IRQs faster if
spuroius interrupts occur during system suspend/resume (that is, for
an irq_desc with IRQS_SUSPENDED set).

Finally, make resume_device_irqs() move irqactions from the list of
"suspended actions" created by suspend_device_irqs() back to the
regular "action" list. It also will clear the IRQS_SPURIOUS_DISABLED
flag for IRQS_SUSPENDED IRQs that were emergency disabled after
suspend_device_irqs() had returned and will log warning messages for
them.

This should address the problematic case (when IRQF_NO_SUSPEND is set
for at least one and unset for at least one irqaction sharing one
irq_desc) and that case only without changing behavior in any other
cases.

It also effectively reverts a previous change to refuse interrupt
requests with IRQF_NO_SUSPEND settings that do not match the
existing ones (as it is not needed any more) and a previous change
that added a IRQD_WAKEUP_STATE check to __disable_irqs() (as that
mechanism has the same problem with shared interrupts as described
above).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

I'm not sure why I make suspend_irq() and resume_irq() return bool
instead of just calling __disable_irq() and __enable_irq() from them
directly in the previous version. Do it better this time.

Rafael

---
include/linux/irqdesc.h | 2 +
kernel/irq/internals.h | 4 +-
kernel/irq/manage.c | 31 +++---------------
kernel/irq/pm.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++--
kernel/irq/spurious.c | 14 +++++++-
5 files changed, 100 insertions(+), 31 deletions(-)

Index: linux-pm/kernel/irq/manage.c
===================================================================
--- linux-pm.orig/kernel/irq/manage.c
+++ linux-pm/kernel/irq/manage.c
@@ -382,15 +382,8 @@ setup_affinity(unsigned int irq, struct
}
#endif

-void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
+void __disable_irq(struct irq_desc *desc, unsigned int irq)
{
- if (suspend) {
- if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND)
- || irqd_has_set(&desc->irq_data, IRQD_WAKEUP_STATE))
- return;
- desc->istate |= IRQS_SUSPENDED;
- }
-
if (!desc->depth++)
irq_disable(desc);
}
@@ -402,7 +395,7 @@ static int __disable_irq_nosync(unsigned

if (!desc)
return -EINVAL;
- __disable_irq(desc, irq, false);
+ __disable_irq(desc, irq);
irq_put_desc_busunlock(desc, flags);
return 0;
}
@@ -443,20 +436,8 @@ void disable_irq(unsigned int irq)
}
EXPORT_SYMBOL(disable_irq);

-void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
+void __enable_irq(struct irq_desc *desc, unsigned int irq)
{
- if (resume) {
- if (!(desc->istate & IRQS_SUSPENDED)) {
- if (!desc->action)
- return;
- if (!(desc->action->flags & IRQF_FORCE_RESUME))
- return;
- /* Pretend that it got disabled ! */
- desc->depth++;
- }
- desc->istate &= ~IRQS_SUSPENDED;
- }
-
switch (desc->depth) {
case 0:
err_out:
@@ -498,7 +479,7 @@ void enable_irq(unsigned int irq)
KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
goto out;

- __enable_irq(desc, irq, false);
+ __enable_irq(desc, irq);
out:
irq_put_desc_busunlock(desc, flags);
}
@@ -1079,7 +1060,7 @@ __setup_irq(unsigned int irq, struct irq
*/

#define IRQF_MISMATCH \
- (IRQF_TRIGGER_MASK | IRQF_ONESHOT | IRQF_NO_SUSPEND)
+ (IRQF_TRIGGER_MASK | IRQF_ONESHOT)

if (!((old->flags & new->flags) & IRQF_SHARED) ||
((old->flags ^ new->flags) & IRQF_MISMATCH))
@@ -1232,7 +1213,7 @@ __setup_irq(unsigned int irq, struct irq
*/
if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
desc->istate &= ~IRQS_SPURIOUS_DISABLED;
- __enable_irq(desc, irq, false);
+ __enable_irq(desc, irq);
}

raw_spin_unlock_irqrestore(&desc->lock, flags);
Index: linux-pm/kernel/irq/spurious.c
===================================================================
--- linux-pm.orig/kernel/irq/spurious.c
+++ linux-pm/kernel/irq/spurious.c
@@ -391,10 +391,20 @@ void note_interrupt(unsigned int irq, st
* otherwise the counter becomes a doomsday timer for otherwise
* working systems
*/
- if (time_after(jiffies, desc->last_unhandled + HZ/10))
+ if (time_after(jiffies, desc->last_unhandled + HZ/10)) {
desc->irqs_unhandled = 1;
- else
+ } else {
desc->irqs_unhandled++;
+ if (unlikely(desc->istate & IRQS_SUSPENDED)) {
+ /*
+ * That shouldn't happen. It means IRQs from
+ * a device that is supposed to be suspended at
+ * this point. Decay faster.
+ */
+ desc->irqs_unhandled += 999;
+ desc->irq_count += 999;
+ }
+ }
desc->last_unhandled = jiffies;
}

Index: linux-pm/include/linux/irqdesc.h
===================================================================
--- linux-pm.orig/include/linux/irqdesc.h
+++ linux-pm/include/linux/irqdesc.h
@@ -20,6 +20,7 @@ struct irq_desc;
* @handle_irq: highlevel irq-events handler
* @preflow_handler: handler called before the flow handler (currently used by sparc)
* @action: the irq action chain
+ * @action_suspended: suspended irq action chain
* @status: status information
* @core_internal_state__do_not_mess_with_it: core internal status information
* @depth: disable-depth, for nested irq_disable() calls
@@ -47,6 +48,7 @@ struct irq_desc {
irq_preflow_handler_t preflow_handler;
#endif
struct irqaction *action; /* IRQ action list */
+ struct irqaction *action_suspended;
unsigned int status_use_accessors;
unsigned int core_internal_state__do_not_mess_with_it;
unsigned int depth; /* nested irq disables */
Index: linux-pm/kernel/irq/internals.h
===================================================================
--- linux-pm.orig/kernel/irq/internals.h
+++ linux-pm/kernel/irq/internals.h
@@ -63,8 +63,8 @@ enum {

extern int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
unsigned long flags);
-extern void __disable_irq(struct irq_desc *desc, unsigned int irq, bool susp);
-extern void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume);
+extern void __disable_irq(struct irq_desc *desc, unsigned int irq);
+extern void __enable_irq(struct irq_desc *desc, unsigned int irq);

extern int irq_startup(struct irq_desc *desc, bool resend);
extern void irq_shutdown(struct irq_desc *desc);
Index: linux-pm/kernel/irq/pm.c
===================================================================
--- linux-pm.orig/kernel/irq/pm.c
+++ linux-pm/kernel/irq/pm.c
@@ -13,6 +13,47 @@

#include "internals.h"

+static void suspend_irq(struct irq_desc *desc, int irq)
+{
+ struct irqaction *action = desc->action;
+ unsigned int no_suspend, flags;
+
+ if (!action)
+ return;
+
+ no_suspend = IRQF_NO_SUSPEND;
+ flags = 0;
+ do {
+ no_suspend &= action->flags;
+ flags |= action->flags;
+ action = action->next;
+ } while (action);
+ if (no_suspend)
+ return;
+
+ desc->istate |= IRQS_SUSPENDED;
+
+ if ((flags & IRQF_NO_SUSPEND) &&
+ !(desc->istate & IRQS_SPURIOUS_DISABLED)) {
+ struct irqaction *no_suspend = NULL;
+
+ do {
+ action = desc->action;
+ desc->action = action->next;
+ if (action->flags & IRQF_NO_SUSPEND) {
+ action->next = no_suspend;
+ no_suspend = action;
+ } else {
+ action->next = desc->action_suspended;
+ desc->action_suspended = action;
+ }
+ } while (desc->action);
+ desc->action = no_suspend;
+ return;
+ }
+ __disable_irq(desc, irq);
+}
+
/**
* suspend_device_irqs - disable all currently enabled interrupt lines
*
@@ -30,7 +71,7 @@ void suspend_device_irqs(void)
unsigned long flags;

raw_spin_lock_irqsave(&desc->lock, flags);
- __disable_irq(desc, irq, true);
+ suspend_irq(desc, irq);
raw_spin_unlock_irqrestore(&desc->lock, flags);
}

@@ -40,6 +81,41 @@ void suspend_device_irqs(void)
}
EXPORT_SYMBOL_GPL(suspend_device_irqs);

+static void resume_irq(struct irq_desc *desc, int irq)
+{
+ if (desc->istate & IRQS_SUSPENDED) {
+ desc->istate &= ~IRQS_SUSPENDED;
+ if (desc->action_suspended) {
+ struct irqaction *action;
+
+ do {
+ action = desc->action_suspended;
+ desc->action_suspended = action->next;
+ action->next = desc->action;
+ desc->action = action;
+ } while (desc->action_suspended);
+
+ if (desc->istate & IRQS_SPURIOUS_DISABLED) {
+ pr_err("Re-enabling emergency disabled IRQ %d\n",
+ irq);
+ desc->istate &= ~IRQS_SPURIOUS_DISABLED;
+ } else {
+ return;
+ }
+ }
+ } else {
+ if (!desc->action)
+ return;
+
+ if (!(desc->action->flags & IRQF_FORCE_RESUME))
+ return;
+
+ /* Pretend that it got disabled ! */
+ desc->depth++;
+ }
+ __enable_irq(desc, irq);
+}
+
static void resume_irqs(bool want_early)
{
struct irq_desc *desc;
@@ -54,7 +130,7 @@ static void resume_irqs(bool want_early)
continue;

raw_spin_lock_irqsave(&desc->lock, flags);
- __enable_irq(desc, irq, true);
+ resume_irq(desc, irq);
raw_spin_unlock_irqrestore(&desc->lock, flags);
}
}