rcu: Remove CONFIG_RCU_CPU_STALL_VERBOSE

The CONFIG_RCU_CPU_STALL_VERBOSE Kconfig parameter causes preemptible
RCU's CPU stall warnings to dump out any preempted tasks that are blocking
the current RCU grace period.  This information is useful, and the default
has been CONFIG_RCU_CPU_STALL_VERBOSE=y for some years.  It is therefore
time for this commit to remove this Kconfig parameter, so that future
kernel builds will always act as if CONFIG_RCU_CPU_STALL_VERBOSE=y.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Documentation/RCU/stallwarn.txt

@@ -26,12 +26,6 @@ CONFIG_RCU_CPU_STALL_TIMEOUT
 	Stall-warning messages may be enabled and disabled completely via
 	/sys/module/rcupdate/parameters/rcu_cpu_stall_suppress.
 
-CONFIG_RCU_CPU_STALL_VERBOSE
-
-	This kernel configuration parameter causes the stall warning to
-	also dump the stacks of any tasks that are blocking the current
-	RCU-preempt grace period.
-
 CONFIG_RCU_CPU_STALL_INFO
 
 	This kernel configuration parameter causes the stall warning to

kernel/rcu/tree_plugin.h

@@ -72,9 +72,6 @@ static void __init rcu_bootup_announce_oddness(void)
 #ifdef CONFIG_RCU_TORTURE_TEST_RUNNABLE
 	pr_info("\tRCU torture testing starts during boot.\n");
 #endif
-#if defined(CONFIG_TREE_PREEMPT_RCU) && !defined(CONFIG_RCU_CPU_STALL_VERBOSE)
-	pr_info("\tDump stacks of tasks blocking RCU-preempt GP.\n");
-#endif
 #if defined(CONFIG_RCU_CPU_STALL_INFO)
 	pr_info("\tAdditional per-CPU info printed with stalls.\n");
 #endif
@@ -415,8 +412,6 @@ void rcu_read_unlock_special(struct task_struct *t)
 	}
 }
 
-#ifdef CONFIG_RCU_CPU_STALL_VERBOSE
-
 /*
  * Dump detailed information for all tasks blocking the current RCU
  * grace period on the specified rcu_node structure.
@@ -451,14 +446,6 @@ static void rcu_print_detail_task_stall(struct rcu_state *rsp)
 		rcu_print_detail_task_stall_rnp(rnp);
 }
 
-#else /* #ifdef CONFIG_RCU_CPU_STALL_VERBOSE */
-
-static void rcu_print_detail_task_stall(struct rcu_state *rsp)
-{
-}
-
-#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_VERBOSE */
-
 #ifdef CONFIG_RCU_CPU_STALL_INFO
 
 static void rcu_print_task_stall_begin(struct rcu_node *rnp)

lib/Kconfig.debug

@@ -1238,18 +1238,6 @@ config RCU_CPU_STALL_TIMEOUT
 	  RCU grace period persists, additional CPU stall warnings are
 	  printed at more widely spaced intervals.
 
-config RCU_CPU_STALL_VERBOSE
-	bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
-	depends on TREE_PREEMPT_RCU
-	default y
-	help
-	  This option causes RCU to printk detailed per-task information
-	  for any tasks that are stalling the current RCU grace period.
-
-	  Say N if you are unsure.
-
-	  Say Y if you want to enable such checks.
-
 config RCU_CPU_STALL_INFO
 	bool "Print additional diagnostics on RCU CPU stall"
 	depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL

tools/testing/selftests/rcutorture/configs/rcu/TREE01

@@ -14,6 +14,5 @@ CONFIG_RCU_NOCB_CPU=y
 CONFIG_RCU_NOCB_CPU_ZERO=y
 CONFIG_DEBUG_LOCK_ALLOC=n
 CONFIG_RCU_CPU_STALL_INFO=n
-CONFIG_RCU_CPU_STALL_VERBOSE=n
 CONFIG_RCU_BOOST=n
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/configs/rcu/TREE02

@@ -19,6 +19,5 @@ CONFIG_RCU_NOCB_CPU=n
 CONFIG_DEBUG_LOCK_ALLOC=y
 CONFIG_PROVE_LOCKING=n
 CONFIG_RCU_CPU_STALL_INFO=n
-CONFIG_RCU_CPU_STALL_VERBOSE=y
 CONFIG_RCU_BOOST=n
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/configs/rcu/TREE02-T

@@ -19,6 +19,5 @@ CONFIG_RCU_NOCB_CPU=n
 CONFIG_DEBUG_LOCK_ALLOC=y
 CONFIG_PROVE_LOCKING=n
 CONFIG_RCU_CPU_STALL_INFO=n
-CONFIG_RCU_CPU_STALL_VERBOSE=y
 CONFIG_RCU_BOOST=n
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/configs/rcu/TREE03

@@ -15,7 +15,6 @@ CONFIG_RCU_FANOUT_EXACT=n
 CONFIG_RCU_NOCB_CPU=n
 CONFIG_DEBUG_LOCK_ALLOC=n
 CONFIG_RCU_CPU_STALL_INFO=n
-CONFIG_RCU_CPU_STALL_VERBOSE=n
 CONFIG_RCU_BOOST=y
 CONFIG_RCU_BOOST_PRIO=2
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/configs/rcu/TREE04

@@ -19,5 +19,4 @@ CONFIG_RCU_FANOUT_EXACT=n
 CONFIG_RCU_NOCB_CPU=n
 CONFIG_DEBUG_LOCK_ALLOC=n
 CONFIG_RCU_CPU_STALL_INFO=y
-CONFIG_RCU_CPU_STALL_VERBOSE=y
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/configs/rcu/TREE05

@@ -19,5 +19,4 @@ CONFIG_DEBUG_LOCK_ALLOC=y
 CONFIG_PROVE_LOCKING=y
 CONFIG_PROVE_RCU=y
 CONFIG_RCU_CPU_STALL_INFO=n
-CONFIG_RCU_CPU_STALL_VERBOSE=n
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/configs/rcu/TREE06

@@ -20,5 +20,4 @@ CONFIG_DEBUG_LOCK_ALLOC=y
 CONFIG_PROVE_LOCKING=y
 CONFIG_PROVE_RCU=y
 CONFIG_RCU_CPU_STALL_INFO=n
-CONFIG_RCU_CPU_STALL_VERBOSE=n
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=y

tools/testing/selftests/rcutorture/configs/rcu/TREE07

@@ -19,5 +19,4 @@ CONFIG_RCU_FANOUT_EXACT=n
 CONFIG_RCU_NOCB_CPU=n
 CONFIG_DEBUG_LOCK_ALLOC=n
 CONFIG_RCU_CPU_STALL_INFO=y
-CONFIG_RCU_CPU_STALL_VERBOSE=n
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/configs/rcu/TREE08

@@ -19,6 +19,5 @@ CONFIG_RCU_NOCB_CPU=y
 CONFIG_RCU_NOCB_CPU_ALL=y
 CONFIG_DEBUG_LOCK_ALLOC=n
 CONFIG_RCU_CPU_STALL_INFO=n
-CONFIG_RCU_CPU_STALL_VERBOSE=n
 CONFIG_RCU_BOOST=n
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/configs/rcu/TREE08-T

@@ -19,6 +19,5 @@ CONFIG_RCU_NOCB_CPU=y
 CONFIG_RCU_NOCB_CPU_ALL=y
 CONFIG_DEBUG_LOCK_ALLOC=n
 CONFIG_RCU_CPU_STALL_INFO=n
-CONFIG_RCU_CPU_STALL_VERBOSE=n
 CONFIG_RCU_BOOST=n
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/configs/rcu/TREE09

@@ -14,6 +14,5 @@ CONFIG_HIBERNATION=n
 CONFIG_RCU_NOCB_CPU=n
 CONFIG_DEBUG_LOCK_ALLOC=n
 CONFIG_RCU_CPU_STALL_INFO=n
-CONFIG_RCU_CPU_STALL_VERBOSE=n
 CONFIG_RCU_BOOST=n
 CONFIG_DEBUG_OBJECTS_RCU_HEAD=n

tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt

@@ -16,8 +16,7 @@ CONFIG_PROVE_LOCKING -- Do all but two, covering CONFIG_PROVE_RCU and not.
 CONFIG_PROVE_RCU -- Do all but one under CONFIG_PROVE_LOCKING.
 CONFIG_RCU_BOOST -- one of TREE_PREEMPT_RCU.
 CONFIG_RCU_BOOST_PRIO -- set to 2 for _BOOST testing.
-CONFIG_RCU_CPU_STALL_INFO -- do one with and without _VERBOSE.
-CONFIG_RCU_CPU_STALL_VERBOSE -- do one with and without _INFO.
+CONFIG_RCU_CPU_STALL_INFO -- Do one.
 CONFIG_RCU_FANOUT -- Cover hierarchy as currently, but overlap with others.
 CONFIG_RCU_FANOUT_EXACT -- Do one.
 CONFIG_RCU_FANOUT_LEAF -- Do one non-default.