[PATCH] rcu: join rcu_ctrlblk and rcu_state

This patch moves rcu_state into the rcu_ctrlblk. I think there
are no reasons why we should have 2 different variables to control
rcu state. Every user of rcu_state has also "rcu_ctrlblk *rcp" in
the parameter list.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 42 insertions, 44 deletions

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index a1d26cb28925..981f9aa43353 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -65,6 +65,10 @@ struct rcu_ctrlblk {
         long    cur;            /* Current batch number.                      */
         long    completed;      /* Number of the last completed batch         */
         int     next_pending;   /* Is the next batch already waiting?         */
+
+        spinlock_t      lock    ____cacheline_internodealigned_in_smp;
+        cpumask_t       cpumask; /* CPUs that need to switch in order    */
+                                 /* for current batch to proceed.        */
 } ____cacheline_internodealigned_in_smp;
 
 /* Is batch a before batch b ? */
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 05ee48316f70..e18f9190eafa 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -49,22 +49,18 @@
 #include <linux/cpu.h>
 
 /* Definition for rcupdate control block. */
-struct rcu_ctrlblk rcu_ctrlblk = 
-        { .cur = -300, .completed = -300 };
-struct rcu_ctrlblk rcu_bh_ctrlblk =
-        { .cur = -300, .completed = -300 };
-
-/* Bookkeeping of the progress of the grace period */
-struct rcu_state {
-        spinlock_t      lock; /* Guard this struct and writes to rcu_ctrlblk */
-        cpumask_t       cpumask; /* CPUs that need to switch in order    */
-                                      /* for current batch to proceed.        */
+struct rcu_ctrlblk rcu_ctrlblk = {
+        .cur = -300,
+        .completed = -300,
+        .lock = SPIN_LOCK_UNLOCKED,
+        .cpumask = CPU_MASK_NONE,
+};
+struct rcu_ctrlblk rcu_bh_ctrlblk = {
+        .cur = -300,
+        .completed = -300,
+        .lock = SPIN_LOCK_UNLOCKED,
+        .cpumask = CPU_MASK_NONE,
 };
-
-static struct rcu_state rcu_state ____cacheline_internodealigned_in_smp =
-          {.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE };
-static struct rcu_state rcu_bh_state ____cacheline_internodealigned_in_smp =
-          {.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE };
 
 DEFINE_PER_CPU(struct rcu_data, rcu_data) = { 0L };
 DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L };
@@ -220,13 +216,13 @@ static void rcu_do_batch(struct rcu_data *rdp)
  *   This is done by rcu_start_batch. The start is not broadcasted to
  *   all cpus, they must pick this up by comparing rcp->cur with
  *   rdp->quiescbatch. All cpus are recorded  in the
- *   rcu_state.cpumask bitmap.
+ *   rcu_ctrlblk.cpumask bitmap.
  * - All cpus must go through a quiescent state.
  *   Since the start of the grace period is not broadcasted, at least two
  *   calls to rcu_check_quiescent_state are required:
  *   The first call just notices that a new grace period is running. The
  *   following calls check if there was a quiescent state since the beginning
- *   of the grace period. If so, it updates rcu_state.cpumask. If
+ *   of the grace period. If so, it updates rcu_ctrlblk.cpumask. If
  *   the bitmap is empty, then the grace period is completed.
  *   rcu_check_quiescent_state calls rcu_start_batch(0) to start the next grace
  *   period (if necessary).
@@ -234,9 +230,9 @@ static void rcu_do_batch(struct rcu_data *rdp)
 /*
  * Register a new batch of callbacks, and start it up if there is currently no
  * active batch and the batch to be registered has not already occurred.
- * Caller must hold rcu_state.lock.
+ * Caller must hold rcu_ctrlblk.lock.
  */
-static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp)
+static void rcu_start_batch(struct rcu_ctrlblk *rcp)
 {
         if (rcp->next_pending &&
                         rcp->completed == rcp->cur) {
@@ -251,11 +247,11 @@ static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp)
                 /*
                  * Accessing nohz_cpu_mask before incrementing rcp->cur needs a
                  * Barrier  Otherwise it can cause tickless idle CPUs to be
-                 * included in rsp->cpumask, which will extend graceperiods
+                 * included in rcp->cpumask, which will extend graceperiods
                  * unnecessarily.
                  */
                 smp_mb();
-                cpus_andnot(rsp->cpumask, cpu_online_map, nohz_cpu_mask);
+                cpus_andnot(rcp->cpumask, cpu_online_map, nohz_cpu_mask);
 
         }
 }
@@ -265,13 +261,13 @@ static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp)
  * Clear it from the cpu mask and complete the grace period if it was the last
  * cpu. Start another grace period if someone has further entries pending
  */
-static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp, struct rcu_state *rsp)
+static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp)
 {
-        cpu_clear(cpu, rsp->cpumask);
-        if (cpus_empty(rsp->cpumask)) {
+        cpu_clear(cpu, rcp->cpumask);
+        if (cpus_empty(rcp->cpumask)) {
                 /* batch completed ! */
                 rcp->completed = rcp->cur;
-                rcu_start_batch(rcp, rsp);
+                rcu_start_batch(rcp);
         }
 }
 
@@ -281,7 +277,7 @@ static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp, struct rcu_state *rsp)
  * quiescent cycle, then indicate that it has done so.
  */
 static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp,
-                        struct rcu_state *rsp, struct rcu_data *rdp)
+                                        struct rcu_data *rdp)
 {
         if (rdp->quiescbatch != rcp->cur) {
                 /* start new grace period: */
@@ -306,15 +302,15 @@ static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp,
                 return;
         rdp->qs_pending = 0;
 
-        spin_lock(&rsp->lock);
+        spin_lock(&rcp->lock);
         /*
          * rdp->quiescbatch/rcp->cur and the cpu bitmap can come out of sync
          * during cpu startup. Ignore the quiescent state.
          */
         if (likely(rdp->quiescbatch == rcp->cur))
-                cpu_quiet(rdp->cpu, rcp, rsp);
+                cpu_quiet(rdp->cpu, rcp);
 
-        spin_unlock(&rsp->lock);
+        spin_unlock(&rcp->lock);
 }
 
 
@@ -335,16 +331,16 @@ static void rcu_move_batch(struct rcu_data *this_rdp, struct rcu_head *list,
 }
 
 static void __rcu_offline_cpu(struct rcu_data *this_rdp,
-        struct rcu_ctrlblk *rcp, struct rcu_state *rsp, struct rcu_data *rdp)
+                                struct rcu_ctrlblk *rcp, struct rcu_data *rdp)
 {
         /* if the cpu going offline owns the grace period
          * we can block indefinitely waiting for it, so flush
          * it here
          */
-        spin_lock_bh(&rsp->lock);
+        spin_lock_bh(&rcp->lock);
         if (rcp->cur != rcp->completed)
-                cpu_quiet(rdp->cpu, rcp, rsp);
-        spin_unlock_bh(&rsp->lock);
+                cpu_quiet(rdp->cpu, rcp);
+        spin_unlock_bh(&rcp->lock);
         rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail);
         rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail);
 
@@ -354,9 +350,9 @@ static void rcu_offline_cpu(int cpu)
         struct rcu_data *this_rdp = &get_cpu_var(rcu_data);
         struct rcu_data *this_bh_rdp = &get_cpu_var(rcu_bh_data);
 
-        __rcu_offline_cpu(this_rdp, &rcu_ctrlblk, &rcu_state,
+        __rcu_offline_cpu(this_rdp, &rcu_ctrlblk,
                                         &per_cpu(rcu_data, cpu));
-        __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk, &rcu_bh_state,
+        __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk,
                                         &per_cpu(rcu_bh_data, cpu));
         put_cpu_var(rcu_data);
         put_cpu_var(rcu_bh_data);
@@ -375,7 +371,7 @@ static void rcu_offline_cpu(int cpu)
  * This does the RCU processing work from tasklet context. 
  */
 static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp,
-                        struct rcu_state *rsp, struct rcu_data *rdp)
+                                        struct rcu_data *rdp)
 {
         if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) {
                 *rdp->donetail = rdp->curlist;
@@ -405,25 +401,23 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp,
 
                 if (!rcp->next_pending) {
                         /* and start it/schedule start if it's a new batch */
-                        spin_lock(&rsp->lock);
+                        spin_lock(&rcp->lock);
                         rcp->next_pending = 1;
-                        rcu_start_batch(rcp, rsp);
-                        spin_unlock(&rsp->lock);
+                        rcu_start_batch(rcp);
+                        spin_unlock(&rcp->lock);
                 }
         } else {
                 local_irq_enable();
         }
-        rcu_check_quiescent_state(rcp, rsp, rdp);
+        rcu_check_quiescent_state(rcp, rdp);
         if (rdp->donelist)
                 rcu_do_batch(rdp);
 }
 
 static void rcu_process_callbacks(unsigned long unused)
 {
-        __rcu_process_callbacks(&rcu_ctrlblk, &rcu_state,
-                                &__get_cpu_var(rcu_data));
-        __rcu_process_callbacks(&rcu_bh_ctrlblk, &rcu_bh_state,
-                                &__get_cpu_var(rcu_bh_data));
+        __rcu_process_callbacks(&rcu_ctrlblk, &__get_cpu_var(rcu_data));
+        __rcu_process_callbacks(&rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data));
 }
 
 static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp)