cpumask: convert RCU implementations

Impact: use new cpumask API.

rcu_ctrlblk contains a cpumask, and it's highly optimized so I don't want
a cpumask_var_t (ie. a pointer) for the CONFIG_CPUMASK_OFFSTACK case.  It
could use a dangling bitmap, and be allocated in __rcu_init to save memory,
but for the moment we use a bitmap.

(Eventually 'struct cpumask' will be undefined for CONFIG_CPUMASK_OFFSTACK,
so we use a bitmap here to show we really mean it).

We remove on-stack cpumasks, using cpumask_var_t for
rcu_torture_shuffle_tasks() and for_each_cpu_and in force_quiescent_state().

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 15 insertions, 12 deletions

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index b3106552210..3245b40952c 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -868,49 +868,52 @@ static int rcu_idle_cpu;	/* Force all torture tasks off this CPU */
  */
 static void rcu_torture_shuffle_tasks(void)
 {
-        cpumask_t tmp_mask;
+        cpumask_var_t tmp_mask;
         int i;
 
-        cpus_setall(tmp_mask);
+        if (!alloc_cpumask_var(&tmp_mask, GFP_KERNEL))
+                BUG();
+
+        cpumask_setall(tmp_mask);
         get_online_cpus();
 
         /* No point in shuffling if there is only one online CPU (ex: UP) */
-        if (num_online_cpus() == 1) {
-                put_online_cpus();
-                return;
-        }
+        if (num_online_cpus() == 1)
+                goto out;
 
         if (rcu_idle_cpu != -1)
-                cpu_clear(rcu_idle_cpu, tmp_mask);
+                cpumask_clear_cpu(rcu_idle_cpu, tmp_mask);
 
-        set_cpus_allowed_ptr(current, &tmp_mask);
+        set_cpus_allowed_ptr(current, tmp_mask);
 
         if (reader_tasks) {
                 for (i = 0; i < nrealreaders; i++)
                         if (reader_tasks[i])
                                 set_cpus_allowed_ptr(reader_tasks[i],
-                                                     &tmp_mask);
+                                                     tmp_mask);
         }
 
         if (fakewriter_tasks) {
                 for (i = 0; i < nfakewriters; i++)
                         if (fakewriter_tasks[i])
                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
-                                                     &tmp_mask);
+                                                     tmp_mask);
         }
 
         if (writer_task)
-                set_cpus_allowed_ptr(writer_task, &tmp_mask);
+                set_cpus_allowed_ptr(writer_task, tmp_mask);
 
         if (stats_task)
-                set_cpus_allowed_ptr(stats_task, &tmp_mask);
+                set_cpus_allowed_ptr(stats_task, tmp_mask);
 
         if (rcu_idle_cpu == -1)
                 rcu_idle_cpu = num_online_cpus() - 1;
         else
                 rcu_idle_cpu--;
 
+out:
         put_online_cpus();
+        free_cpumask_var(tmp_mask);
 }
 
 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the