[PATCH v2 tip/core/rcu 7/9] rcutorture: Print symbolic name for ->gp_state

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

Currently, ->gp_state is printed as an integer, which slows debugging.
This commit therefore prints a symbolic name in addition to the integer.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Updated to fix relational operator called out by Dan Carpenter. ]
[ paulmck: More "const", as suggested by Josh Triplett. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
---
 kernel/rcu/tree.c | 15 +++++++++++++--
 kernel/rcu/tree.h | 12 ++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7b78c88e19a3..316354109734 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1187,6 +1187,16 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
 }
 
 /*
+ * Convert a ->gp_state value to a character string.
+ */
+static const char *gp_state_getname(short gs)
+{
+	if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
+		return "???";
+	return gp_state_names[gs];
+}
+
+/*
  * Complain about starvation of grace-period kthread.
  */
 static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
@@ -1197,10 +1207,11 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
 	j = jiffies;
 	gpa = READ_ONCE(rsp->gp_activity);
 	if (j - gpa > 2 * HZ) {
-		pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x s%d ->state=%#lx\n",
+		pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x %s(%d) ->state=%#lx\n",
 		       rsp->name, j - gpa,
 		       rsp->gpnum, rsp->completed,
-		       rsp->gp_flags, rsp->gp_state,
+		       rsp->gp_flags,
+		       gp_state_getname(rsp->gp_state), rsp->gp_state,
 		       rsp->gp_kthread ? rsp->gp_kthread->state : ~0);
 		if (rsp->gp_kthread)
 			sched_show_task(rsp->gp_kthread);
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index f32bebb6bc90..a3fb6fe94127 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -545,6 +545,18 @@ struct rcu_state {
 #define RCU_GP_CLEANUP   5	/* Grace-period cleanup started. */
 #define RCU_GP_CLEANED   6	/* Grace-period cleanup complete. */
 
+#ifndef RCU_TREE_NONCORE
+static const char * const gp_state_names[] = {
+	"RCU_GP_IDLE",
+	"RCU_GP_WAIT_GPS",
+	"RCU_GP_DONE_GPS",
+	"RCU_GP_WAIT_FQS",
+	"RCU_GP_DOING_FQS",
+	"RCU_GP_CLEANUP",
+	"RCU_GP_CLEANED",
+};
+#endif /* #ifndef RCU_TREE_NONCORE */
+
 extern struct list_head rcu_struct_flavors;
 
 /* Sequence through rcu_state structures for each RCU flavor. */
-- 
2.5.2