EXPERIMENTAL and incomplete patch to make LOCKDEP behave better in
the face of irq chaining, by annotating irqs with a lock_class which
can reflect that hierarchy.
This version of the patch is incomplete in at least two respects:
- There's no spin_lock_irq_nested() primitive, so that locking calls
on irq probing (yeech!) paths must ignore the annotations.
==> LOCKDEP feature is evidently missing:
spin_lock_irq_nested(lock_ptr, lock_class)
- We'd really need new API to declare the parent/child relationships
between IRQs to handle this properly. Lacking such calls, this just
piggybacks set_irq_chained_handler() to modify the parent's class.
That's a problem, since only the lowest level of any lock tree gets
accurate nesting annotations. On the plus side: no platform changes
are needed this way, so testing is easy.
==> GENIRQ programming interface evidently missing
set_irq_parent(parent_irqnum, child_irqnum) (?)
Example: when a GPIO controller's set_wake() handler needs to call its
parent's set_irq_wake() method to ensure all appropriate signal paths are
set up, that currently generates a bogus lockdep warning. This patch
removes those bogus warnings ... when there's only one level of parent.
---
include/linux/irq.h | 3 +++
kernel/irq/autoprobe.c | 5 +++++
kernel/irq/chip.c | 44 ++++++++++++++++++++++++++++----------------
kernel/irq/handle.c | 4 ++--
kernel/irq/manage.c | 12 ++++++------
kernel/irq/migration.c | 2 +-
kernel/irq/proc.c | 2 +-
kernel/irq/spurious.c | 6 +++---
8 files changed, 49 insertions(+), 29 deletions(-)
--- a/include/linux/irq.h 2008-01-17 22:25:53.000000000 -0800
+++ b/include/linux/irq.h 2008-01-18 00:08:57.000000000 -0800
@@ -164,6 +164,9 @@ struct irq_desc {
unsigned int irqs_unhandled;
unsigned long last_unhandled; /* Aging timer for unhandled
count */
spinlock_t lock;
+#ifdef CONFIG_LOCKDEP
+ unsigned int lock_class; /* for chained irqs */
+#endif
#ifdef CONFIG_SMP
cpumask_t affinity;
unsigned int cpu;
--- a/kernel/irq/autoprobe.c 2008-01-17 22:25:53.000000000 -0800
+++ b/kernel/irq/autoprobe.c 2008-01-18 00:08:57.000000000 -0800
@@ -41,6 +41,7 @@ unsigned long probe_irq_on(void)
for (i = NR_IRQS-1; i > 0; i--) {
desc = irq_desc + i;
+/* FIXME nested */
spin_lock_irq(&desc->lock);
if (!desc->action && !(desc->status & IRQ_NOPROBE)) {
/*
@@ -71,6 +72,7 @@ unsigned long probe_irq_on(void)
for (i = NR_IRQS-1; i > 0; i--) {
desc = irq_desc + i;
+/* FIXME nested */
spin_lock_irq(&desc->lock);
if (!desc->action && !(desc->status & IRQ_NOPROBE)) {
desc->status |= IRQ_AUTODETECT | IRQ_WAITING;
@@ -93,6 +95,7 @@ unsigned long probe_irq_on(void)
unsigned int status;
desc = irq_desc + i;
+/* FIXME nested */
spin_lock_irq(&desc->lock);
status = desc->status;
@@ -134,6 +137,7 @@ unsigned int probe_irq_mask(unsigned lon
struct irq_desc *desc = irq_desc + i;
unsigned int status;
+/* FIXME nested */
spin_lock_irq(&desc->lock);
status = desc->status;
@@ -177,6 +181,7 @@ int probe_irq_off(unsigned long val)
struct irq_desc *desc = irq_desc + i;
unsigned int status;
+/* FIXME nested */
spin_lock_irq(&desc->lock);
status = desc->status;
--- a/kernel/irq/chip.c 2008-01-17 22:25:52.000000000 -0800
+++ b/kernel/irq/chip.c 2008-01-18 14:20:21.000000000 -0800
@@ -35,7 +35,7 @@ void dynamic_irq_init(unsigned int irq)
/* Ensure we don't have left over values from a previous use of this
irq */
desc = irq_desc + irq;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
desc->status = IRQ_DISABLED;
desc->chip = &no_irq_chip;
desc->handle_irq = handle_bad_irq;
@@ -68,7 +68,7 @@ void dynamic_irq_cleanup(unsigned int ir
}
desc = irq_desc + irq;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
if (desc->action) {
spin_unlock_irqrestore(&desc->lock, flags);
printk(KERN_ERR "Destroying IRQ%d without calling free_irq\n",
@@ -105,7 +105,7 @@ int set_irq_chip(unsigned int irq, struc
chip = &no_irq_chip;
desc = irq_desc + irq;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
irq_chip_set_defaults(chip);
desc->chip = chip;
spin_unlock_irqrestore(&desc->lock, flags);
@@ -132,7 +132,7 @@ int set_irq_type(unsigned int irq, unsig
desc = irq_desc + irq;
if (desc->chip->set_type) {
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
ret = desc->chip->set_type(irq, type);
spin_unlock_irqrestore(&desc->lock, flags);
}
@@ -159,7 +159,7 @@ int set_irq_data(unsigned int irq, void
}
desc = irq_desc + irq;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
desc->handler_data = data;
spin_unlock_irqrestore(&desc->lock, flags);
return 0;
@@ -184,7 +184,7 @@ int set_irq_msi(unsigned int irq, struct
return -EINVAL;
}
desc = irq_desc + irq;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
desc->msi_desc = entry;
if (entry)
entry->irq = irq;
@@ -209,7 +209,7 @@ int set_irq_chip_data(unsigned int irq,
return -EINVAL;
}
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
desc->chip_data = data;
spin_unlock_irqrestore(&desc->lock, flags);
@@ -293,7 +293,7 @@ handle_simple_irq(unsigned int irq, stru
irqreturn_t action_ret;
const unsigned int cpu = smp_processor_id();
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out_unlock;
@@ -311,7 +311,7 @@ handle_simple_irq(unsigned int irq, stru
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
desc->status &= ~IRQ_INPROGRESS;
out_unlock:
spin_unlock(&desc->lock);
@@ -334,7 +334,7 @@ handle_level_irq(unsigned int irq, struc
struct irqaction *action;
irqreturn_t action_ret;
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
mask_ack_irq(desc, irq);
if (unlikely(desc->status & IRQ_INPROGRESS))
@@ -357,7 +357,7 @@ handle_level_irq(unsigned int irq, struc
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
desc->status &= ~IRQ_INPROGRESS;
if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
desc->chip->unmask(irq);
@@ -382,7 +382,7 @@ handle_fasteoi_irq(unsigned int irq, str
struct irqaction *action;
irqreturn_t action_ret;
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out;
@@ -410,7 +410,7 @@ handle_fasteoi_irq(unsigned int irq, str
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
desc->status &= ~IRQ_INPROGRESS;
out:
desc->chip->eoi(irq);
@@ -439,7 +439,7 @@ handle_edge_irq(unsigned int irq, struct
{
const unsigned int cpu = smp_processor_id();
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
@@ -489,7 +489,7 @@ handle_edge_irq(unsigned int irq, struct
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
} while ((desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING);
@@ -553,7 +553,7 @@ __set_irq_handler(unsigned int irq, irq_
desc->chip = &dummy_irq_chip;
}
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
/* Uninstall? */
if (handle == handle_bad_irq) {
@@ -570,6 +570,18 @@ __set_irq_handler(unsigned int irq, irq_
desc->status |= IRQ_NOREQUEST | IRQ_NOPROBE;
desc->depth = 0;
desc->chip->unmask(irq);
+
+#ifdef CONFIG_LOCKDEP
+ /* REVISIT this only handles a single level of chaining.
+ * A better solution would use a new interface setting
+ * the child's lock_class to one more than the parent's;
+ * but genirq doesn't currently link parents to children.
+ *
+ * REVISIT should this even work? We already grabbed the
+ * lock with the wrong class annotation, above...
+ */
+ desc->lock_class++;
+#endif
}
spin_unlock_irqrestore(&desc->lock, flags);
}
--- a/kernel/irq/handle.c 2008-01-17 22:25:52.000000000 -0800
+++ b/kernel/irq/handle.c 2008-01-18 00:08:57.000000000 -0800
@@ -187,7 +187,7 @@ fastcall unsigned int __do_IRQ(unsigned
return 1;
}
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
if (desc->chip->ack)
desc->chip->ack(irq);
/*
@@ -237,7 +237,7 @@ fastcall unsigned int __do_IRQ(unsigned
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
if (likely(!(desc->status & IRQ_PENDING)))
break;
desc->status &= ~IRQ_PENDING;
--- a/kernel/irq/manage.c 2008-01-17 22:25:52.000000000 -0800
+++ b/kernel/irq/manage.c 2008-01-18 00:08:57.000000000 -0800
@@ -45,7 +45,7 @@ void synchronize_irq(unsigned int irq)
cpu_relax();
/* Ok, that indicated we're done: double-check carefully. */
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
status = desc->status;
spin_unlock_irqrestore(&desc->lock, flags);
@@ -115,7 +115,7 @@ void disable_irq_nosync(unsigned int irq
if (irq >= NR_IRQS)
return;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
if (!desc->depth++) {
desc->status |= IRQ_DISABLED;
desc->chip->disable(irq);
@@ -167,7 +167,7 @@ void enable_irq(unsigned int irq)
if (irq >= NR_IRQS)
return;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
switch (desc->depth) {
case 0:
printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
@@ -210,7 +210,7 @@ int set_irq_wake(unsigned int irq, unsig
/* wakeup-capable irqs can be shared between drivers that
* don't need to have the same sleep mode behaviors.
*/
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
if (on) {
if (desc->wake_depth++ == 0)
desc->status |= IRQ_WAKEUP;
@@ -301,7 +301,7 @@ int setup_irq(unsigned int irq, struct i
/*
* The following block of code has to be executed atomically
*/
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
p = &desc->action;
old = *p;
if (old) {
@@ -427,7 +427,7 @@ void free_irq(unsigned int irq, void *de
return;
desc = irq_desc + irq;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
p = &desc->action;
for (;;) {
struct irqaction *action = *p;
--- a/kernel/irq/migration.c 2008-01-17 22:25:53.000000000 -0800
+++ b/kernel/irq/migration.c 2008-01-18 00:08:57.000000000 -0800
@@ -6,7 +6,7 @@ void set_pending_irq(unsigned int irq, c
struct irq_desc *desc = irq_desc + irq;
unsigned long flags;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
desc->status |= IRQ_MOVE_PENDING;
irq_desc[irq].pending_mask = mask;
spin_unlock_irqrestore(&desc->lock, flags);
--- a/kernel/irq/proc.c 2008-01-17 22:25:53.000000000 -0800
+++ b/kernel/irq/proc.c 2008-01-18 00:08:57.000000000 -0800
@@ -84,7 +84,7 @@ static int name_unique(unsigned int irq,
unsigned long flags;
int ret = 1;
- spin_lock_irqsave(&desc->lock, flags);
+ spin_lock_irqsave_nested(&desc->lock, flags, desc->lock_class);
for (action = desc->action ; action; action = action->next) {
if ((action != new_action) && action->name &&
!strcmp(new_action->name, action->name)) {
--- a/kernel/irq/spurious.c 2008-01-17 22:25:52.000000000 -0800
+++ b/kernel/irq/spurious.c 2008-01-18 00:08:57.000000000 -0800
@@ -29,7 +29,7 @@ static int misrouted_irq(int irq)
if (i == irq) /* Already tried */
continue;
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
/* Already running on another processor */
if (desc->status & IRQ_INPROGRESS) {
/*
@@ -57,7 +57,7 @@ static int misrouted_irq(int irq)
}
local_irq_disable();
/* Now clean up the flags */
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
action = desc->action;
/*
@@ -71,7 +71,7 @@ static int misrouted_irq(int irq)
work = 1;
spin_unlock(&desc->lock);
handle_IRQ_event(i, action);
- spin_lock(&desc->lock);
+ spin_lock_nested(&desc->lock, desc->lock_class);
desc->status &= ~IRQ_PENDING;
}
desc->status &= ~IRQ_INPROGRESS;
--
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