From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Sat, 13 Aug 2011 09:14:28 +0000 (+0100)
Subject: x86: IRQ fix incorrect logic in __clear_irq_vector
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~9967
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=1a9b16687d54c660c83c8d8554d7b08c3cec6895;p=xen.git

x86: IRQ fix incorrect logic in __clear_irq_vector

In the old code, tmp_mask is the cpu_and of cfg->cpu_mask and
cpu_online_map.  However, in the usual case of moving an IRQ from one
PCPU to another because the scheduler decides its a good idea,
cfg->cpu_mask and cfg->old_cpu_mask do not intersect.  This causes the
old cpu vector_irq table to keep the irq reference when it shouldn't.

This leads to a resource leak if a domain is shut down wile an irq has
a move pending, which results in Xen's create_irq() eventually failing
with -ENOSPC when all vector_irq tables are full of stale references.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index dfec057b42..8d598c28ca 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -216,6 +216,7 @@ static void __clear_irq_vector(int irq)
 
     if (likely(!cfg->move_in_progress))
         return;
+    cpus_and(tmp_mask, cfg->old_cpu_mask, cpu_online_map);
     for_each_cpu_mask(cpu, tmp_mask) {
         for (vector = FIRST_DYNAMIC_VECTOR; vector <= LAST_DYNAMIC_VECTOR;
                                 vector++) {