irq, x86: fix lock status with numa_migrate_irq_desc

Eric Paris reported:

> I have an hp dl785g5 which is unable to successfully run
> 2.6.29-0.66.rc3.fc11.x86_64 or 2.6.29-rc2-next-20090126.  During bootup
> (early in userspace daemons starting) I get the below BUG, which quickly
> renders the machine dead.  I assume it is because sparse_irq_lock never
> gets released when the BUG kills that task.

Adjust lock sequence when migrating a descriptor with
CONFIG_NUMA_MIGRATE_IRQ_DESC enabled.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 1 deletions

diff --git a/kernel/irq/numa_migrate.c b/kernel/irq/numa_migrate.c
index ecf765c6a77a..acd88356ac76 100644
--- a/kernel/irq/numa_migrate.c
+++ b/kernel/irq/numa_migrate.c
@@ -71,7 +71,7 @@ static struct irq_desc *__real_move_irq_desc(struct irq_desc *old_desc,
         desc = irq_desc_ptrs[irq];
 
         if (desc && old_desc != desc)
-                        goto out_unlock;
+                goto out_unlock;
 
         node = cpu_to_node(cpu);
         desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
@@ -84,10 +84,15 @@ static struct irq_desc *__real_move_irq_desc(struct irq_desc *old_desc,
         init_copy_one_irq_desc(irq, old_desc, desc, cpu);
 
         irq_desc_ptrs[irq] = desc;
+        spin_unlock_irqrestore(&sparse_irq_lock, flags);
 
         /* free the old one */
         free_one_irq_desc(old_desc, desc);
+        spin_unlock(&old_desc->lock);
         kfree(old_desc);
+        spin_lock(&desc->lock);
+
+        return desc;
 
 out_unlock:
         spin_unlock_irqrestore(&sparse_irq_lock, flags);