Thomas, as discussed previously over IRC and private email. Please
apply.
At present set_irq_handler() and all the existing variants take the
desc->lock for the irq in question before adjusting the irq's flow
handler. This can cause problems for irq chips for which a given
interrupt can be either level or edge depending on what's attached.
The chip->set_type() callback, which is used to switch the interrupt
type in this case may need to alter the flow handler - but it is
called with the desc->lock already held, so it cannot safely call
set_irq_handler().
This patch pulls the core logic out of set_irq_handler() into a new
set_irq_handler_locked() which assumes the desc->lock is already held.
It can safely be used from the chip->set_type() callback.
Signed-off-by: David Gibson <[email protected]>
Index: working-2.6/kernel/irq/chip.c
===================================================================
--- working-2.6.orig/kernel/irq/chip.c 2007-01-24 12:01:21.000000000 +1100
+++ working-2.6/kernel/irq/chip.c 2007-02-09 14:28:55.000000000 +1100
@@ -500,6 +500,43 @@ handle_percpu_irq(unsigned int irq, stru
#endif /* CONFIG_SMP */
+/**
+ * set_irq_handler_locked - Set irq flow handler. *
+ * @irq: the interrupt number
+ * @handle: the flow handler function
+ * @is_chained: is this a chained handler (used for cascade interrupts)
+ * @name: name for this handler, usually "level" or "edge"
+ *
+ * This version of set_irq_handler() assumes that desc->lock for
+ * the interrupt in question is already taken. In particular,
+ * this means it is safe to call from a chip->set_type() callback
+ * function.
+ */
+void set_irq_handler_locked(unsigned int irq, irq_flow_handler_t handle,
+ int is_chained, const char *name)
+{
+ struct irq_desc *desc = irq_desc + irq;
+
+ /* Uninstall? */
+ if (handle == handle_bad_irq) {
+ if (desc->chip != &no_irq_chip) {
+ desc->chip->mask(irq);
+ desc->chip->ack(irq);
+ }
+ desc->status |= IRQ_DISABLED;
+ desc->depth = 1;
+ }
+ desc->handle_irq = handle;
+ desc->name = name;
+
+ if (handle != handle_bad_irq && is_chained) {
+ desc->status &= ~IRQ_DISABLED;
+ desc->status |= IRQ_NOREQUEST | IRQ_NOPROBE;
+ desc->depth = 0;
+ desc->chip->unmask(irq);
+ }
+}
+
void
__set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
const char *name)
@@ -531,25 +568,7 @@ __set_irq_handler(unsigned int irq, irq_
}
spin_lock_irqsave(&desc->lock, flags);
-
- /* Uninstall? */
- if (handle == handle_bad_irq) {
- if (desc->chip != &no_irq_chip) {
- desc->chip->mask(irq);
- desc->chip->ack(irq);
- }
- desc->status |= IRQ_DISABLED;
- desc->depth = 1;
- }
- desc->handle_irq = handle;
- desc->name = name;
-
- if (handle != handle_bad_irq && is_chained) {
- desc->status &= ~IRQ_DISABLED;
- desc->status |= IRQ_NOREQUEST | IRQ_NOPROBE;
- desc->depth = 0;
- desc->chip->unmask(irq);
- }
+ set_irq_handler_locked(irq, handle, is_chained, name);
spin_unlock_irqrestore(&desc->lock, flags);
}
Index: working-2.6/include/linux/irq.h
===================================================================
--- working-2.6.orig/include/linux/irq.h 2007-01-24 12:01:21.000000000 +1100
+++ working-2.6/include/linux/irq.h 2007-02-09 14:04:12.000000000 +1100
@@ -329,6 +329,9 @@ set_irq_chip_and_handler_name(unsigned i
irq_flow_handler_t handle, const char *name);
extern void
+set_irq_handler_locked(unsigned int irq, irq_flow_handler_t handle,
+ int is_chained, const char *name);
+extern void
__set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
const char *name);
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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