diff options
| -rw-r--r-- | include/linux/rculist.h | 32 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 7 | ||||
| -rw-r--r-- | kernel/rcu/Kconfig.debug | 11 | ||||
| -rw-r--r-- | kernel/rcu/update.c | 96 |
4 files changed, 108 insertions, 38 deletions
diff --git a/include/linux/rculist.h b/include/linux/rculist.h index 932296144131..4158b7212936 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -41,6 +41,24 @@ 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. * * This is only for internal list manipulation where we know @@ -343,14 +361,16 @@ 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) \ - for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \ - &pos->member != (head); \ +#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); \ pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) /** @@ -616,13 +636,15 @@ 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) \ - for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\ +#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)),\ 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 bfcafbc1e301..80d6056f5855 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -221,6 +221,7 @@ 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 */ @@ -241,6 +242,12 @@ 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 5ec3ea4028e2..4aa02eee8f6c 100644 --- a/kernel/rcu/Kconfig.debug +++ b/kernel/rcu/Kconfig.debug @@ -8,6 +8,17 @@ 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 9dd5aeef6e70..38cbd616b381 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -61,9 +61,15 @@ module_param(rcu_normal_after_boot, int, 0); #ifdef CONFIG_DEBUG_LOCK_ALLOC /** - * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section? + * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section? + * @ret: Best guess answer if lockdep cannot be relied on * - * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an + * Returns true if lockdep must be ignored, in which case *ret contains + * the best guess described below. Otherwise returns false, in which + * case *ret tells the caller nothing and the caller should instead + * consult lockdep. + * + * If CONFIG_DEBUG_LOCK_ALLOC is selected, set *ret to nonzero iff in an * RCU-sched read-side critical section. In absence of * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side * critical section unless it can prove otherwise. Note that disabling @@ -75,30 +81,44 @@ module_param(rcu_normal_after_boot, int, 0); * Check debug_lockdep_rcu_enabled() to prevent false positives during boot * and while lockdep is disabled. * - * Note that if the CPU is in the idle loop from an RCU point of - * view (ie: that we are in the section between rcu_idle_enter() and - * rcu_idle_exit()) then rcu_read_lock_held() returns false even if the CPU - * did an rcu_read_lock(). The reason for this is that RCU ignores CPUs - * that are in such a section, considering these as in extended quiescent - * state, so such a CPU is effectively never in an RCU read-side critical - * section regardless of what RCU primitives it invokes. This state of - * affairs is required --- we need to keep an RCU-free window in idle - * where the CPU may possibly enter into low power mode. This way we can - * notice an extended quiescent state to other CPUs that started a grace - * period. Otherwise we would delay any grace period as long as we run in - * the idle task. + * Note that if the CPU is in the idle loop from an RCU point of view (ie: + * that we are in the section between rcu_idle_enter() and rcu_idle_exit()) + * then rcu_read_lock_held() sets *ret to false even if the CPU did an + * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are + * in such a section, considering these as in extended quiescent state, + * so such a CPU is effectively never in an RCU read-side critical section + * regardless of what RCU primitives it invokes. This state of affairs is + * required --- we need to keep an RCU-free window in idle where the CPU may + * possibly enter into low power mode. This way we can notice an extended + * quiescent state to other CPUs that started a grace period. Otherwise + * we would delay any grace period as long as we run in the idle task. * - * Similarly, we avoid claiming an SRCU read lock held if the current + * Similarly, we avoid claiming an RCU 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) { - if (!debug_lockdep_rcu_enabled()) - return 1; - if (!rcu_is_watching()) - return 0; - if (!rcu_lockdep_current_cpu_online()) - return 0; + bool ret; + + if (rcu_read_lock_held_common(&ret)) + return ret; return lock_is_held(&rcu_sched_lock_map) || !preemptible(); } EXPORT_SYMBOL(rcu_read_lock_sched_held); @@ -257,12 +277,10 @@ NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled); */ int rcu_read_lock_held(void) { - if (!debug_lockdep_rcu_enabled()) - return 1; - if (!rcu_is_watching()) - return 0; - if (!rcu_lockdep_current_cpu_online()) - return 0; + bool ret; + + if (rcu_read_lock_held_common(&ret)) + return ret; return lock_is_held(&rcu_lock_map); } EXPORT_SYMBOL_GPL(rcu_read_lock_held); @@ -284,16 +302,28 @@ EXPORT_SYMBOL_GPL(rcu_read_lock_held); */ int rcu_read_lock_bh_held(void) { - if (!debug_lockdep_rcu_enabled()) - return 1; - if (!rcu_is_watching()) - return 0; - if (!rcu_lockdep_current_cpu_online()) - return 0; + bool ret; + + if (rcu_read_lock_held_common(&ret)) + return ret; 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 */ /** |