lguest: fix for CONFIG_SPARSE_IRQ=y

Impact: remove lots of lguest boot WARN_ON() when CONFIG_SPARSE_IRQ=y

We now need to call irq_to_desc_alloc_cpu() before
set_irq_chip_and_handler_name(), but we can't do that from init_IRQ (no
kmalloc available).

So do it as we use interrupts instead.  Also means we only alloc for
irqs we use, which was the intent of CONFIG_SPARSE_IRQ anyway.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>

2 files changed, 15 insertions, 7 deletions

diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index ba5c05e97f10..960a8d9c049c 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -594,19 +594,21 @@ static void __init lguest_init_IRQ(void)
                 /* Some systems map "vectors" to interrupts weirdly.  Lguest has
                  * a straightforward 1 to 1 mapping, so force that here. */
                 __get_cpu_var(vector_irq)[vector] = i;
-                if (vector != SYSCALL_VECTOR) {
-                        set_intr_gate(vector,
-                                      interrupt[vector-FIRST_EXTERNAL_VECTOR]);
-                        set_irq_chip_and_handler_name(i, &lguest_irq_controller,
-                                                      handle_level_irq,
-                                                      "level");
-                }
+                if (vector != SYSCALL_VECTOR)
+                        set_intr_gate(vector, interrupt[i]);
         }
         /* This call is required to set up for 4k stacks, where we have
          * separate stacks for hard and soft interrupts. */
         irq_ctx_init(smp_processor_id());
 }
 
+void lguest_setup_irq(unsigned int irq)
+{
+        irq_to_desc_alloc_cpu(irq, 0);
+        set_irq_chip_and_handler_name(irq, &lguest_irq_controller,
+                                      handle_level_irq, "level");
+}
+
 /*
  * Time.
  *
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index b4d44e571d76..8132533d71f9 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -212,6 +212,9 @@ static void lg_notify(struct virtqueue *vq)
         hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0);
 }
 
+/* An extern declaration inside a C file is bad form.  Don't do it. */
+extern void lguest_setup_irq(unsigned int irq);
+
 /* This routine finds the first virtqueue described in the configuration of
  * this device and sets it up.
  *
@@ -266,6 +269,9 @@ static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
                 goto unmap;
         }
 
+        /* Make sure the interrupt is allocated. */
+        lguest_setup_irq(lvq->config.irq);
+
         /* Tell the interrupt for this virtqueue to go to the virtio_ring
          * interrupt handler. */
         /* FIXME: We used to have a flag for the Host to tell us we could use