rcu: merge TREE_PREEPT_RCU blocked_tasks[] lists

Combine the current TREE_PREEMPT_RCU ->blocked_tasks[] lists in the
rcu_node structure into a single ->blkd_tasks list with ->gp_tasks
and ->exp_tasks tail pointers.  This is in preparation for RCU priority
boosting, which will add a third dimension to the combinatorial explosion
in the ->blocked_tasks[] case, but simply a third pointer in the new
->blkd_tasks case.

Also update documentation to reflect blocked_tasks[] merge

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 4 insertions, 7 deletions

diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index 4a21ca55ef7c..1cedf94e2c4f 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -161,7 +161,6 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 {
         unsigned long gpnum;
         int level = 0;
-        int phase;
         struct rcu_node *rnp;
 
         gpnum = rsp->gpnum;
@@ -178,13 +177,11 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
                         seq_puts(m, "\n");
                         level = rnp->level;
                 }
-                phase = gpnum & 0x1;
-                seq_printf(m, "%lx/%lx %c%c>%c%c %d:%d ^%d    ",
+                seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d    ",
                            rnp->qsmask, rnp->qsmaskinit,
-                           "T."[list_empty(&rnp->blocked_tasks[phase])],
-                           "E."[list_empty(&rnp->blocked_tasks[phase + 2])],
-                           "T."[list_empty(&rnp->blocked_tasks[!phase])],
-                           "E."[list_empty(&rnp->blocked_tasks[!phase + 2])],
+                           ".G"[rnp->gp_tasks != NULL],
+                           ".E"[rnp->exp_tasks != NULL],
+                           ".T"[!list_empty(&rnp->blkd_tasks)],
                            rnp->grplo, rnp->grphi, rnp->grpnum);
         }
         seq_puts(m, "\n");