[Xen-devel] [PATCH] workaround for bug#197

[Ryan Harper <ryanh@xxxxxxxxxx>]

I don't think this is the right fix, but it does highlight the issue.
While killing a domain, the vcpus are descheduled, but every
now and then, one of the cpus is still running one of the vcpus, which
means d->cpumask is not empty.   This triggers the BUG_ON() in
xen/arch/x86/domain.c:domain_relinquish_resources().  The patch puts in
some printks and a cpu_relax() loop till the cpumask is empty before
calling domain_relinquish_resources().   With this patch, I've gone
through several thousand iterations of create/destroy without crashing.

--
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@xxxxxxxxxx


diffstat output:
 domain.c |    8 ++++++++
 1 files changed, 8 insertions(+)

Signed-off-by: Ryan Harper <ryanh@xxxxxxxxxx>
---

diff -r 413c911e5780 xen/common/domain.c
--- a/xen/common/domain.c       Mon Sep 12 12:48:33 2005
+++ b/xen/common/domain.c       Mon Sep 12 13:25:07 2005
@@ -112,6 +112,14 @@
     {
         for_each_vcpu(d, v)
             sched_rem_domain(v);
+        if(!cpus_empty(d->cpumask)) {
+            printk("ACK! DOM%d still running, waiting before dying\n",
+                   d->domain_id);
+            while(!cpus_empty(d->cpumask))
+                cpu_relax();
+            printk("DOM%d cpumask clear, relinquishing resources\n", 
+                   d->domain_id);
+        }                
         domain_relinquish_resources(d);
         put_domain(d);
 

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