From: Keir Fraser <keir.fraser@citrix.com>
Date: Thu, 16 Oct 2008 17:36:43 +0000 (+0100)
Subject: Fix SCHEDOP_poll to avoid wakeup-waiting race on interrupt delivery.
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~14066^2~37
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success//%22http:/www.example.com/cgi/success/?a=commitdiff_plain;h=27b186a0dbe932c15195a24a520b92a2d2282d92;p=xen.git

Fix SCHEDOP_poll to avoid wakeup-waiting race on interrupt delivery.

Race found by Jan Beulich.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
---

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 12882d0204..04b09e2168 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -455,6 +455,10 @@ static long do_poll(struct sched_poll *sched_poll)
         goto out;
 #endif
 
+    rc = 0;
+    if ( local_events_need_delivery() )
+        goto out;
+
     for ( i = 0; i < sched_poll->nr_ports; i++ )
     {
         rc = -EFAULT;