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Message-Id: <20190801181411.96429-3-joel@joelfernandes.org>
Date: Thu, 1 Aug 2019 14:14:04 -0400
From: "Joel Fernandes (Google)" <joel@...lfernandes.org>
To: linux-kernel@...r.kernel.org
Cc: "Joel Fernandes (Google)" <joel@...lfernandes.org>,
"Paul E. McKenney" <paulmck@...ux.ibm.com>, rcu@...r.kernel.org
Subject: [PATCH 2/9] Revert "rcu: Add support for consolidated-RCU reader checking"
This reverts commit 50ad3f1f9b13c8a6f2ae79df4cecb2c21da1c7c8.
---
include/linux/rculist.h | 32 ++++----------------
include/linux/rcupdate.h | 7 -----
kernel/rcu/Kconfig.debug | 11 -------
kernel/rcu/update.c | 65 ++++++++++++++--------------------------
4 files changed, 27 insertions(+), 88 deletions(-)
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 4158b7212936..932296144131 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -40,24 +40,6 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
*/
#define list_next_rcu(list) (*((struct list_head __rcu **)(&(list)->next)))
-/*
- * Check during list traversal that we are within an RCU reader
- */
-
-#define check_arg_count_one(dummy)
-
-#ifdef CONFIG_PROVE_RCU_LIST
-#define __list_check_rcu(dummy, cond, extra...) \
- ({ \
- check_arg_count_one(extra); \
- RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(), \
- "RCU-list traversed in non-reader section!"); \
- })
-#else
-#define __list_check_rcu(dummy, cond, extra...) \
- ({ check_arg_count_one(extra); })
-#endif
-
/*
* Insert a new entry between two known consecutive entries.
*
@@ -361,16 +343,14 @@ static inline void list_splice_tail_init_rcu(struct list_head *list,
* @pos: the type * to use as a loop cursor.
* @head: the head for your list.
* @member: the name of the list_head within the struct.
- * @cond: optional lockdep expression if called from non-RCU protection.
*
* This list-traversal primitive may safely run concurrently with
* the _rcu list-mutation primitives such as list_add_rcu()
* as long as the traversal is guarded by rcu_read_lock().
*/
-#define list_for_each_entry_rcu(pos, head, member, cond...) \
- for (__list_check_rcu(dummy, ## cond, 0), \
- pos = list_entry_rcu((head)->next, typeof(*pos), member); \
- &pos->member != (head); \
+#define list_for_each_entry_rcu(pos, head, member) \
+ for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
+ &pos->member != (head); \
pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
/**
@@ -636,15 +616,13 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
* @pos: the type * to use as a loop cursor.
* @head: the head for your list.
* @member: the name of the hlist_node within the struct.
- * @cond: optional lockdep expression if called from non-RCU protection.
*
* This list-traversal primitive may safely run concurrently with
* the _rcu list-mutation primitives such as hlist_add_head_rcu()
* as long as the traversal is guarded by rcu_read_lock().
*/
-#define hlist_for_each_entry_rcu(pos, head, member, cond...) \
- for (__list_check_rcu(dummy, ## cond, 0), \
- pos = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\
+#define hlist_for_each_entry_rcu(pos, head, member) \
+ for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\
typeof(*(pos)), member); \
pos; \
pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 80d6056f5855..bfcafbc1e301 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -221,7 +221,6 @@ int debug_lockdep_rcu_enabled(void);
int rcu_read_lock_held(void);
int rcu_read_lock_bh_held(void);
int rcu_read_lock_sched_held(void);
-int rcu_read_lock_any_held(void);
#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
@@ -242,12 +241,6 @@ static inline int rcu_read_lock_sched_held(void)
{
return !preemptible();
}
-
-static inline int rcu_read_lock_any_held(void)
-{
- return !preemptible();
-}
-
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
#ifdef CONFIG_PROVE_RCU
diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug
index 4aa02eee8f6c..5ec3ea4028e2 100644
--- a/kernel/rcu/Kconfig.debug
+++ b/kernel/rcu/Kconfig.debug
@@ -8,17 +8,6 @@ menu "RCU Debugging"
config PROVE_RCU
def_bool PROVE_LOCKING
-config PROVE_RCU_LIST
- bool "RCU list lockdep debugging"
- depends on PROVE_RCU && RCU_EXPERT
- default n
- help
- Enable RCU lockdep checking for list usages. By default it is
- turned off since there are several list RCU users that still
- need to be converted to pass a lockdep expression. To prevent
- false-positive splats, we keep it default disabled but once all
- users are converted, we can remove this config option.
-
config TORTURE_TEST
tristate
default n
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index c768f1fd6804..64e9cc8609e7 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -91,30 +91,19 @@ module_param(rcu_normal_after_boot, int, 0);
* Similarly, we avoid claiming an SRCU read lock held if the current
* CPU is offline.
*/
-static bool rcu_read_lock_held_common(bool *ret)
-{
- if (!debug_lockdep_rcu_enabled()) {
- *ret = 1;
- return true;
- }
- if (!rcu_is_watching()) {
- *ret = 0;
- return true;
- }
- if (!rcu_lockdep_current_cpu_online()) {
- *ret = 0;
- return true;
- }
- return false;
-}
-
int rcu_read_lock_sched_held(void)
{
- bool ret;
+ int lockdep_opinion = 0;
- if (rcu_read_lock_held_common(&ret))
- return ret;
- return lock_is_held(&rcu_sched_lock_map) || !preemptible();
+ if (!debug_lockdep_rcu_enabled())
+ return 1;
+ if (!rcu_is_watching())
+ return 0;
+ if (!rcu_lockdep_current_cpu_online())
+ return 0;
+ if (debug_locks)
+ lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
+ return lockdep_opinion || !preemptible();
}
EXPORT_SYMBOL(rcu_read_lock_sched_held);
#endif
@@ -271,10 +260,12 @@ NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled);
*/
int rcu_read_lock_held(void)
{
- bool ret;
-
- if (rcu_read_lock_held_common(&ret))
- return ret;
+ if (!debug_lockdep_rcu_enabled())
+ return 1;
+ if (!rcu_is_watching())
+ return 0;
+ if (!rcu_lockdep_current_cpu_online())
+ return 0;
return lock_is_held(&rcu_lock_map);
}
EXPORT_SYMBOL_GPL(rcu_read_lock_held);
@@ -296,28 +287,16 @@ EXPORT_SYMBOL_GPL(rcu_read_lock_held);
*/
int rcu_read_lock_bh_held(void)
{
- bool ret;
-
- if (rcu_read_lock_held_common(&ret))
- return ret;
+ if (!debug_lockdep_rcu_enabled())
+ return 1;
+ if (!rcu_is_watching())
+ return 0;
+ if (!rcu_lockdep_current_cpu_online())
+ return 0;
return in_softirq() || irqs_disabled();
}
EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
-int rcu_read_lock_any_held(void)
-{
- bool ret;
-
- if (rcu_read_lock_held_common(&ret))
- return ret;
- if (lock_is_held(&rcu_lock_map) ||
- lock_is_held(&rcu_bh_lock_map) ||
- lock_is_held(&rcu_sched_lock_map))
- return 1;
- return !preemptible();
-}
-EXPORT_SYMBOL_GPL(rcu_read_lock_any_held);
-
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
/**
--
2.22.0.770.g0f2c4a37fd-goog
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