xen/sched: only allow schedulers with all mandatory functions available

Some functions of struct scheduler are mandatory. Test those in the
scheduler initialization loop to be present and drop schedulers not
complying.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Dario Faggioli <dfaggioli@suse.com>

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 86341bc8fbb9359bcf43608fffb26553ca8ac0c7..b671aeadb7347d110965a17f4c51cc893cacf327 100644 (file)
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -1727,9 +1727,33 @@ void __init scheduler_init(void)
 
     for ( i = 0; i < NUM_SCHEDULERS; i++)
     {
+#define sched_test_func(f)                               \
+        if ( !schedulers[i]->f )                         \
+        {                                                \
+            printk("scheduler %s misses .%s, dropped\n", \
+                   schedulers[i]->opt_name, #f);         \
+            schedulers[i] = NULL;                        \
+        }
+
+        sched_test_func(init);
+        sched_test_func(deinit);
+        sched_test_func(pick_cpu);
+        sched_test_func(alloc_vdata);
+        sched_test_func(free_vdata);
+        sched_test_func(switch_sched);
+        sched_test_func(do_schedule);
+
+#undef sched_test_func
+
         if ( schedulers[i]->global_init && schedulers[i]->global_init() < 0 )
+        {
+            printk("scheduler %s failed initialization, dropped\n",
+                   schedulers[i]->opt_name);
             schedulers[i] = NULL;
-        else if ( !ops.name && !strcmp(schedulers[i]->opt_name, opt_sched) )
+        }
+
+        if ( schedulers[i] && !ops.name &&
+             !strcmp(schedulers[i]->opt_name, opt_sched) )
             ops = *schedulers[i];
     }