[PATCH] fix deadlock in drivers/pci/msi.c

The lock validator caught another one: drivers/pci/msi.c is accessing
&irq_desc[i].lock with interrupts enabled (!).

The fix is to disable interrupts properly.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/pci/msi.c

@@ -416,7 +416,9 @@ static void attach_msi_entry(struct msi_desc *entry, int vector)
 
 static void irq_handler_init(int cap_id, int pos, int mask)
 {
-	spin_lock(&irq_desc[pos].lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&irq_desc[pos].lock, flags);
 	if (cap_id == PCI_CAP_ID_MSIX)
 		irq_desc[pos].handler = &msix_irq_type;
 	else {
@@ -425,7 +427,7 @@ static void irq_handler_init(int cap_id, int pos, int mask)
 		else
 			irq_desc[pos].handler = &msi_irq_w_maskbit_type;
 	}
-	spin_unlock(&irq_desc[pos].lock);
+	spin_unlock_irqrestore(&irq_desc[pos].lock, flags);
 }
 
 static void enable_msi_mode(struct pci_dev *dev, int pos, int type)