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, 10 insertions, 9 deletions

diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index 04982659875a..f9dc8f3720f6 100644
--- a/kernel/rcupreempt.c
+++ b/kernel/rcupreempt.c
@@ -164,7 +164,8 @@ static char *rcu_try_flip_state_names[] =
         { "idle", "waitack", "waitzero", "waitmb" };
 #endif /* #ifdef CONFIG_RCU_TRACE */
 
-static cpumask_t rcu_cpu_online_map __read_mostly = CPU_MASK_NONE;
+static DECLARE_BITMAP(rcu_cpu_online_map, NR_CPUS) __read_mostly
+        = CPU_BITS_NONE;
 
 /*
  * Enum and per-CPU flag to determine when each CPU has seen
@@ -758,7 +759,7 @@ rcu_try_flip_idle(void)
 
         /* Now ask each CPU for acknowledgement of the flip. */
 
-        for_each_cpu_mask_nr(cpu, rcu_cpu_online_map) {
+        for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map)) {
                 per_cpu(rcu_flip_flag, cpu) = rcu_flipped;
                 dyntick_save_progress_counter(cpu);
         }
@@ -776,7 +777,7 @@ rcu_try_flip_waitack(void)
         int cpu;
 
         RCU_TRACE_ME(rcupreempt_trace_try_flip_a1);
-        for_each_cpu_mask_nr(cpu, rcu_cpu_online_map)
+        for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map))
                 if (rcu_try_flip_waitack_needed(cpu) &&
                     per_cpu(rcu_flip_flag, cpu) != rcu_flip_seen) {
                         RCU_TRACE_ME(rcupreempt_trace_try_flip_ae1);
@@ -808,7 +809,7 @@ rcu_try_flip_waitzero(void)
         /* Check to see if the sum of the "last" counters is zero. */
 
         RCU_TRACE_ME(rcupreempt_trace_try_flip_z1);
-        for_each_cpu_mask_nr(cpu, rcu_cpu_online_map)
+        for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map))
                 sum += RCU_DATA_CPU(cpu)->rcu_flipctr[lastidx];
         if (sum != 0) {
                 RCU_TRACE_ME(rcupreempt_trace_try_flip_ze1);
@@ -823,7 +824,7 @@ rcu_try_flip_waitzero(void)
         smp_mb();  /*  ^^^^^^^^^^^^ */
 
         /* Call for a memory barrier from each CPU. */
-        for_each_cpu_mask_nr(cpu, rcu_cpu_online_map) {
+        for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map)) {
                 per_cpu(rcu_mb_flag, cpu) = rcu_mb_needed;
                 dyntick_save_progress_counter(cpu);
         }
@@ -843,7 +844,7 @@ rcu_try_flip_waitmb(void)
         int cpu;
 
         RCU_TRACE_ME(rcupreempt_trace_try_flip_m1);
-        for_each_cpu_mask_nr(cpu, rcu_cpu_online_map)
+        for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map))
                 if (rcu_try_flip_waitmb_needed(cpu) &&
                     per_cpu(rcu_mb_flag, cpu) != rcu_mb_done) {
                         RCU_TRACE_ME(rcupreempt_trace_try_flip_me1);
@@ -1032,7 +1033,7 @@ void rcu_offline_cpu(int cpu)
         RCU_DATA_CPU(cpu)->rcu_flipctr[0] = 0;
         RCU_DATA_CPU(cpu)->rcu_flipctr[1] = 0;
 
-        cpu_clear(cpu, rcu_cpu_online_map);
+        cpumask_clear_cpu(cpu, to_cpumask(rcu_cpu_online_map));
 
         spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags);
 
@@ -1072,7 +1073,7 @@ void __cpuinit rcu_online_cpu(int cpu)
         struct rcu_data *rdp;
 
         spin_lock_irqsave(&rcu_ctrlblk.fliplock, flags);
-        cpu_set(cpu, rcu_cpu_online_map);
+        cpumask_set_cpu(cpu, to_cpumask(rcu_cpu_online_map));
         spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags);
 
         /*
@@ -1430,7 +1431,7 @@ void __init __rcu_init(void)
          * We don't need protection against CPU-Hotplug here
          * since
          * a) If a CPU comes online while we are iterating over the
-         *    cpu_online_map below, we would only end up making a
+         *    cpu_online_mask below, we would only end up making a
          *    duplicate call to rcu_online_cpu() which sets the corresponding
          *    CPU's mask in the rcu_cpu_online_map.
          *