[PATCH tip/core/rcu 88/88] rcu: Remove RCU CPU stall warnings from Tiny RCU
From: Paul E. McKenney
Date: Thu May 25 2017 - 18:11:01 EST
Tiny RCU's job is to be tiny, so this commit removes its RCU CPU
stall warning code. After this, there is no longer any need for
rcu_sched_ctrlblk and rcu_bh_ctrlblk to be in tiny_plugin.h, so this
commit also moves them to tiny.c.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/Kconfig | 2 +-
kernel/rcu/tiny.c | 35 +++++-----
kernel/rcu/tiny_plugin.h | 78 ----------------------
.../selftests/rcutorture/configs/rcu/TINY02 | 1 -
4 files changed, 19 insertions(+), 97 deletions(-)
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index 8edff43e8e94..be90c945063f 100644
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -78,7 +78,7 @@ config TASKS_RCU
user-mode execution as quiescent states.
config RCU_STALL_COMMON
- def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
+ def_bool ( TREE_RCU || PREEMPT_RCU )
help
This option enables RCU CPU stall code that is common between
the TINY and TREE variants of RCU. The purpose is to allow
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 595cb1bf944f..f8488965250f 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -38,11 +38,23 @@
#include "rcu.h"
-/* Forward declarations for tiny_plugin.h. */
-struct rcu_ctrlblk;
-static void __call_rcu(struct rcu_head *head,
- rcu_callback_t func,
- struct rcu_ctrlblk *rcp);
+/* Global control variables for rcupdate callback mechanism. */
+struct rcu_ctrlblk {
+ struct rcu_head *rcucblist; /* List of pending callbacks (CBs). */
+ struct rcu_head **donetail; /* ->next pointer of last "done" CB. */
+ struct rcu_head **curtail; /* ->next pointer of last CB. */
+};
+
+/* Definition for rcupdate control block. */
+static struct rcu_ctrlblk rcu_sched_ctrlblk = {
+ .donetail = &rcu_sched_ctrlblk.rcucblist,
+ .curtail = &rcu_sched_ctrlblk.rcucblist,
+};
+
+static struct rcu_ctrlblk rcu_bh_ctrlblk = {
+ .donetail = &rcu_bh_ctrlblk.rcucblist,
+ .curtail = &rcu_bh_ctrlblk.rcucblist,
+};
#include "tiny_plugin.h"
@@ -65,7 +77,6 @@ EXPORT_SYMBOL(rcu_barrier_sched);
*/
static int rcu_qsctr_help(struct rcu_ctrlblk *rcp)
{
- RCU_TRACE(reset_cpu_stall_ticks(rcp);)
if (rcp->donetail != rcp->curtail) {
rcp->donetail = rcp->curtail;
return 1;
@@ -111,7 +122,6 @@ void rcu_bh_qs(void)
*/
void rcu_check_callbacks(int user)
{
- RCU_TRACE(check_cpu_stalls();)
if (user)
rcu_sched_qs();
else if (!in_softirq())
@@ -126,10 +136,8 @@ void rcu_check_callbacks(int user)
*/
static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
{
- const char *rn = NULL;
struct rcu_head *next, *list;
unsigned long flags;
- RCU_TRACE(int cb_count = 0;)
/* Move the ready-to-invoke callbacks to a local list. */
local_irq_save(flags);
@@ -147,18 +155,15 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
local_irq_restore(flags);
/* Invoke the callbacks on the local list. */
- RCU_TRACE(rn = rcp->name;)
while (list) {
next = list->next;
prefetch(next);
debug_rcu_head_unqueue(list);
local_bh_disable();
- __rcu_reclaim(rn, list);
+ __rcu_reclaim("", list);
local_bh_enable();
list = next;
- RCU_TRACE(cb_count++;)
}
- RCU_TRACE(rcu_trace_sub_qlen(rcp, cb_count);)
}
static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
@@ -202,7 +207,6 @@ static void __call_rcu(struct rcu_head *head,
local_irq_save(flags);
*rcp->curtail = head;
rcp->curtail = &head->next;
- RCU_TRACE(rcp->qlen++;)
local_irq_restore(flags);
if (unlikely(is_idle_task(current))) {
@@ -235,8 +239,5 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
void __init rcu_init(void)
{
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
- RCU_TRACE(reset_cpu_stall_ticks(&rcu_sched_ctrlblk);)
- RCU_TRACE(reset_cpu_stall_ticks(&rcu_bh_ctrlblk);)
-
rcu_early_boot_tests();
}
diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h
index c642f23f1582..f0a01b2a3062 100644
--- a/kernel/rcu/tiny_plugin.h
+++ b/kernel/rcu/tiny_plugin.h
@@ -22,34 +22,6 @@
* Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
*/
-#include <linux/kthread.h>
-#include <linux/init.h>
-
-/* Global control variables for rcupdate callback mechanism. */
-struct rcu_ctrlblk {
- struct rcu_head *rcucblist; /* List of pending callbacks (CBs). */
- struct rcu_head **donetail; /* ->next pointer of last "done" CB. */
- struct rcu_head **curtail; /* ->next pointer of last CB. */
- RCU_TRACE(long qlen); /* Number of pending CBs. */
- RCU_TRACE(unsigned long gp_start); /* Start time for stalls. */
- RCU_TRACE(unsigned long ticks_this_gp); /* Statistic for stalls. */
- RCU_TRACE(unsigned long jiffies_stall); /* Jiffies at next stall. */
- RCU_TRACE(const char *name); /* Name of RCU type. */
-};
-
-/* Definition for rcupdate control block. */
-static struct rcu_ctrlblk rcu_sched_ctrlblk = {
- .donetail = &rcu_sched_ctrlblk.rcucblist,
- .curtail = &rcu_sched_ctrlblk.rcucblist,
- RCU_TRACE(.name = "rcu_sched")
-};
-
-static struct rcu_ctrlblk rcu_bh_ctrlblk = {
- .donetail = &rcu_bh_ctrlblk.rcucblist,
- .curtail = &rcu_bh_ctrlblk.rcucblist,
- RCU_TRACE(.name = "rcu_bh")
-};
-
#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU)
#include <linux/kernel_stat.h>
@@ -73,53 +45,3 @@ void __init rcu_scheduler_starting(void)
}
#endif /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */
-
-#ifdef CONFIG_RCU_TRACE
-
-static void rcu_trace_sub_qlen(struct rcu_ctrlblk *rcp, int n)
-{
- unsigned long flags;
-
- local_irq_save(flags);
- rcp->qlen -= n;
- local_irq_restore(flags);
-}
-
-static void check_cpu_stall(struct rcu_ctrlblk *rcp)
-{
- unsigned long j;
- unsigned long js;
-
- if (rcu_cpu_stall_suppress)
- return;
- rcp->ticks_this_gp++;
- j = jiffies;
- js = READ_ONCE(rcp->jiffies_stall);
- if (rcp->rcucblist && ULONG_CMP_GE(j, js)) {
- pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n",
- rcp->name, rcp->ticks_this_gp, DYNTICK_TASK_EXIT_IDLE,
- jiffies - rcp->gp_start, rcp->qlen);
- dump_stack();
- WRITE_ONCE(rcp->jiffies_stall,
- jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
- } else if (ULONG_CMP_GE(j, js)) {
- WRITE_ONCE(rcp->jiffies_stall,
- jiffies + rcu_jiffies_till_stall_check());
- }
-}
-
-static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp)
-{
- rcp->ticks_this_gp = 0;
- rcp->gp_start = jiffies;
- WRITE_ONCE(rcp->jiffies_stall,
- jiffies + rcu_jiffies_till_stall_check());
-}
-
-static void check_cpu_stalls(void)
-{
- RCU_TRACE(check_cpu_stall(&rcu_bh_ctrlblk);)
- RCU_TRACE(check_cpu_stall(&rcu_sched_ctrlblk);)
-}
-
-#endif /* #ifdef CONFIG_RCU_TRACE */
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TINY02 b/tools/testing/selftests/rcutorture/configs/rcu/TINY02
index 1f6bebbf5da8..d8674264318d 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TINY02
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TINY02
@@ -6,7 +6,6 @@ CONFIG_PREEMPT=n
CONFIG_HZ_PERIODIC=y
CONFIG_NO_HZ_IDLE=n
CONFIG_NO_HZ_FULL=n
-CONFIG_RCU_TRACE=y
CONFIG_PROVE_LOCKING=y
#CHECK#CONFIG_PROVE_RCU=y
CONFIG_DEBUG_LOCK_ALLOC=y
--
2.5.2