rcu: Remove conditional compilation for RCU CPU stall warnings

The RCU CPU stall warnings can now be controlled using the
rcu_cpu_stall_suppress boot-time parameter or via the same parameter
from sysfs.  There is therefore no longer any reason to have
kernel config parameters for this feature.  This commit therefore
removes the RCU_CPU_STALL_DETECTOR and RCU_CPU_STALL_DETECTOR_RUNNABLE
kernel config parameters.  The RCU_CPU_STALL_TIMEOUT parameter remains
to allow the timeout to be tuned and the RCU_CPU_STALL_VERBOSE parameter
remains to allow task-stall information to be suppressed if desired.

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

3 files changed, 1 insertions, 49 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index dd4aea806f8e..18f7a593d4c7 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -140,10 +140,8 @@ module_param(blimit, int, 0);
 module_param(qhimark, int, 0);
 module_param(qlowmark, int, 0);
 
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
-int rcu_cpu_stall_suppress __read_mostly = RCU_CPU_STALL_SUPPRESS_INIT;
+int rcu_cpu_stall_suppress __read_mostly;
 module_param(rcu_cpu_stall_suppress, int, 0644);
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
 
 static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
 static int rcu_pending(int cpu);
@@ -450,8 +448,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 
 #endif /* #else #ifdef CONFIG_NO_HZ */
 
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
-
 int rcu_cpu_stall_suppress __read_mostly;
 
 static void record_gp_stall_check_time(struct rcu_state *rsp)
@@ -587,26 +583,6 @@ static void __init check_cpu_stall_init(void)
         atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
 }
 
-#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-
-static void record_gp_stall_check_time(struct rcu_state *rsp)
-{
-}
-
-static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-}
-
-void rcu_cpu_stall_reset(void)
-{
-}
-
-static void __init check_cpu_stall_init(void)
-{
-}
-
-#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-
 /*
  * Update CPU-local rcu_data state to record the newly noticed grace period.
  * This is used both when we started the grace period and when we notice
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index e8f057e44e3e..e1a6663c0155 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -254,7 +254,6 @@ struct rcu_data {
 #endif /* #else #ifdef CONFIG_NO_HZ */
 
 #define RCU_JIFFIES_TILL_FORCE_QS        3      /* for rsp->jiffies_force_qs */
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
 
 #ifdef CONFIG_PROVE_RCU
 #define RCU_STALL_DELAY_DELTA          (5 * HZ)
@@ -272,13 +271,6 @@ struct rcu_data {
                                                 /*  scheduling clock irq */
                                                 /*  before ratting on them. */
 
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR_RUNNABLE
-#define RCU_CPU_STALL_SUPPRESS_INIT 0
-#else
-#define RCU_CPU_STALL_SUPPRESS_INIT 1
-#endif
-
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
 
 /*
  * RCU global state, including node hierarchy.  This hierarchy is
@@ -325,12 +317,10 @@ struct rcu_state {
                                                 /*  due to lock unavailable. */
         unsigned long n_force_qs_ngp;           /* Number of calls leaving */
                                                 /*  due to no GP active. */
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
         unsigned long gp_start;                 /* Time at which GP started, */
                                                 /*  but in jiffies. */
         unsigned long jiffies_stall;            /* Time at which to check */
                                                 /*  for CPU stalls. */
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
         char *name;                             /* Name of structure. */
 };
 
@@ -366,11 +356,9 @@ static int rcu_preempted_readers(struct rcu_node *rnp);
 static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
                                       unsigned long flags);
 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
 static void rcu_print_task_stall(struct rcu_node *rnp);
 static void rcu_preempt_stall_reset(void);
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
 #ifdef CONFIG_HOTPLUG_CPU
 static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index a3638710dc67..38426ef1bcd6 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -54,10 +54,6 @@ static void __init rcu_bootup_announce_oddness(void)
 #ifdef CONFIG_RCU_TORTURE_TEST_RUNNABLE
         printk(KERN_INFO "\tRCU torture testing starts during boot.\n");
 #endif
-#ifndef CONFIG_RCU_CPU_STALL_DETECTOR
-        printk(KERN_INFO
-               "\tRCU-based detection of stalled CPUs is disabled.\n");
-#endif
 #if defined(CONFIG_TREE_PREEMPT_RCU) && !defined(CONFIG_RCU_CPU_STALL_VERBOSE)
         printk(KERN_INFO "\tVerbose stalled-CPUs detection is disabled.\n");
 #endif
@@ -356,8 +352,6 @@ void __rcu_read_unlock(void)
 }
 EXPORT_SYMBOL_GPL(__rcu_read_unlock);
 
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
-
 #ifdef CONFIG_RCU_CPU_STALL_VERBOSE
 
 /*
@@ -430,8 +424,6 @@ static void rcu_preempt_stall_reset(void)
         rcu_preempt_state.jiffies_stall = jiffies + ULONG_MAX / 2;
 }
 
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-
 /*
  * Check that the list of blocked tasks for the newly completed grace
  * period is in fact empty.  It is a serious bug to complete a grace
@@ -862,8 +854,6 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags)
 
 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
-
 /*
  * Because preemptable RCU does not exist, we never have to check for
  * tasks blocked within RCU read-side critical sections.
@@ -888,8 +878,6 @@ static void rcu_preempt_stall_reset(void)
 {
 }
 
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-
 /*
  * Because there is no preemptable RCU, there can be no readers blocked,
  * so there is no need to check for blocked tasks.  So check only for