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Subject[rfc] x86,ioapic: panic on irq-pin binding only if needed
Though the most time we are to panic on irq-pin allocation
fails, for PCI interrupts it's not the case and we could
continue operate even if irq-pin allocation failed.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
---

Please review. Not sure that it's a best solution at all
but allow us to not panic in case of PCI irq routing fails.

But note that irq descriptor is allocated anyway in such
a case. Perhaps we need to bring in irq_descr freeing
function as well. Or what is more likelihood is that
I'm missing something. Yinghai?

arch/x86/kernel/apic/io_apic.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)

Index: linux-2.6.git/arch/x86/kernel/apic/io_apic.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/apic/io_apic.c
+++ linux-2.6.git/arch/x86/kernel/apic/io_apic.c
@@ -490,7 +490,8 @@ static void ioapic_mask_entry(int apic,
* shared ISA-space IRQs, so we have to support them. We are super
* fast in the common case, and fast for shared ISA-space IRQs.
*/
-static void add_pin_to_irq_node(struct irq_cfg *cfg, int node, int apic, int pin)
+static int
+add_pin_to_irq_node_nopanic(struct irq_cfg *cfg, int node, int apic, int pin)
{
struct irq_pin_list **last, *entry;

@@ -498,19 +499,27 @@ static void add_pin_to_irq_node(struct i
last = &cfg->irq_2_pin;
for_each_irq_pin(entry, cfg->irq_2_pin) {
if (entry->apic == apic && entry->pin == pin)
- return;
+ return 0;
last = &entry->next;
}

entry = get_one_free_irq_2_pin(node);
if (!entry) {
- printk(KERN_ERR "can not alloc irq_pin_list\n");
- BUG_ON(1);
+ printk(KERN_ERR "can not alloc irq_pin_list (%d,%d,%d)\n",
+ node, apic, pin);
+ return -ENOMEM;
}
entry->apic = apic;
entry->pin = pin;

*last = entry;
+ return 0;
+}
+
+static void add_pin_to_irq_node(struct irq_cfg *cfg, int node, int apic, int pin)
+{
+ if (add_pin_to_irq_node_nopanic(cfg, node, apic, pin))
+ panic("IO-APIC: failed to add irq-pin. Can not proceed\n");
}

/*
@@ -3846,7 +3855,11 @@ static int __io_apic_set_pci_routing(str
*/
if (irq >= NR_IRQS_LEGACY) {
cfg = desc->chip_data;
- add_pin_to_irq_node(cfg, node, ioapic, pin);
+ if (add_pin_to_irq_node_nopanic(cfg, node, ioapic, pin)) {
+ printk(KERN_INFO "can not add pin %d for irq %d\n",
+ pin, irq);
+ return 0;
+ }
}

setup_IO_APIC_irq(ioapic, pin, irq, desc, trigger, polarity);

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