[Xen-devel] [PATCH 14/14] xen: events: propagate irq allocation failure instead of panicking

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

Running out of IRQs need not be fatal to the machine as a whole.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
---
 drivers/xen/events.c |   22 ++++++++++++++--------
 1 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 7c36689..3566c00 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -406,7 +406,7 @@ static void xen_irq_init(unsigned irq)
        list_add_tail(&info->list, &xen_irq_list_head);
 }
 
-static int xen_allocate_irq_dynamic(void)
+static int __must_check xen_allocate_irq_dynamic(void)
 {
        int first = 0;
        int irq;
@@ -425,15 +425,12 @@ static int xen_allocate_irq_dynamic(void)
 
        irq = irq_alloc_desc_from(first, -1);
 
-       if (irq < 0)
-               panic("No available IRQ to bind to: increase nr_irqs!\n");
-
        xen_irq_init(irq);
 
        return irq;
 }
 
-static int xen_allocate_irq_gsi(unsigned gsi)
+static int __must_check xen_allocate_irq_gsi(unsigned gsi)
 {
        int irq;
 
@@ -452,9 +449,6 @@ static int xen_allocate_irq_gsi(unsigned gsi)
        else
                irq = irq_alloc_desc_at(gsi, -1);
 
-       if (irq < 0)
-               panic("Unable to allocate to IRQ%d (%d)\n", gsi, irq);
-
        xen_irq_init(irq);
 
        return irq;
@@ -640,6 +634,8 @@ int xen_bind_pirq_gsi_to_irq(unsigned gsi,
        }
 
        irq = xen_allocate_irq_gsi(gsi);
+       if (irq < 0)
+               goto out;
 
        set_irq_chip_and_handler_name(irq, &xen_pirq_chip,
                                      handle_level_irq, name);
@@ -771,6 +767,8 @@ int bind_evtchn_to_irq(unsigned int evtchn)
 
        if (irq == -1) {
                irq = xen_allocate_irq_dynamic();
+               if (irq == -1)
+                       goto out;
 
                set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
                                              handle_fasteoi_irq, "event");
@@ -778,6 +776,7 @@ int bind_evtchn_to_irq(unsigned int evtchn)
                xen_irq_info_evtchn_init(irq, evtchn);
        }
 
+out:
        spin_unlock(&irq_mapping_update_lock);
 
        return irq;
@@ -829,6 +828,8 @@ int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
 
        if (irq == -1) {
                irq = xen_allocate_irq_dynamic();
+               if (irq == -1)
+                       goto out;
 
                set_irq_chip_and_handler_name(irq, &xen_percpu_chip,
                                              handle_percpu_irq, "virq");
@@ -845,6 +846,7 @@ int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
                bind_evtchn_to_cpu(evtchn, cpu);
        }
 
+out:
        spin_unlock(&irq_mapping_update_lock);
 
        return irq;
@@ -897,6 +899,8 @@ int bind_evtchn_to_irqhandler(unsigned int evtchn,
        int retval;
 
        irq = bind_evtchn_to_irq(evtchn);
+       if (irq < 0)
+               return irq;
        retval = request_irq(irq, handler, irqflags, devname, dev_id);
        if (retval != 0) {
                unbind_from_irq(irq);
@@ -915,6 +919,8 @@ int bind_virq_to_irqhandler(unsigned int virq, unsigned int 
cpu,
        int retval;
 
        irq = bind_virq_to_irq(virq, cpu);
+       if (irq < 0)
+               return irq;
        retval = request_irq(irq, handler, irqflags, devname, dev_id);
        if (retval != 0) {
                unbind_from_irq(irq);
-- 
1.5.6.5


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