[PATCH 3/3] xen/cpupool: fix removing cpu from a cpupool

[Juergen Gross <jgross@suse.com>]

Commit cb563d7665f2 ("xen/sched: support core scheduling for moving
cpus to/from cpupools") introduced a regression when trying to remove
an offline cpu from a cpupool, as the system would crash in this
situation.

Fix that by testing the cpu to be online.

Fixes: cb563d7665f2 ("xen/sched: support core scheduling for moving cpus to/from cpupools")
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 xen/common/sched/cpupool.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/xen/common/sched/cpupool.c b/xen/common/sched/cpupool.c
index d40345b585..de9e25af84 100644
--- a/xen/common/sched/cpupool.c
+++ b/xen/common/sched/cpupool.c
@@ -520,6 +520,9 @@ static int cpupool_unassign_cpu(struct cpupool *c, unsigned int cpu)
     debugtrace_printk("cpupool_unassign_cpu(pool=%d,cpu=%d)\n",
                       c->cpupool_id, cpu);
 
+    if ( !cpu_online(cpu) )
+        return -EINVAL;
+
     master_cpu = sched_get_resource_cpu(cpu);
     ret = cpupool_unassign_cpu_start(c, master_cpu);
     if ( ret )
-- 
2.16.4