diff options
Diffstat (limited to 'include/linux/rcupdate.h')
| -rw-r--r-- | include/linux/rcupdate.h | 371 |
1 files changed, 58 insertions, 313 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index e1e5d002fdb9..1a9f70d44af9 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -34,104 +34,15 @@ #define __LINUX_RCUPDATE_H #include <linux/types.h> -#include <linux/cache.h> -#include <linux/spinlock.h> -#include <linux/threads.h> -#include <linux/cpumask.h> -#include <linux/seqlock.h> -#include <linux/lockdep.h> -#include <linux/debugobjects.h> -#include <linux/bug.h> #include <linux/compiler.h> -#include <linux/ktime.h> +#include <linux/atomic.h> #include <linux/irqflags.h> +#include <linux/preempt.h> +#include <linux/bottom_half.h> +#include <linux/lockdep.h> +#include <asm/processor.h> +#include <linux/cpumask.h> -#include <asm/barrier.h> - -#ifndef CONFIG_TINY_RCU -extern int rcu_expedited; /* for sysctl */ -extern int rcu_normal; /* also for sysctl */ -#endif /* #ifndef CONFIG_TINY_RCU */ - -#ifdef CONFIG_TINY_RCU -/* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */ -static inline bool rcu_gp_is_normal(void) /* Internal RCU use. */ -{ - return true; -} -static inline bool rcu_gp_is_expedited(void) /* Internal RCU use. */ -{ - return false; -} - -static inline void rcu_expedite_gp(void) -{ -} - -static inline void rcu_unexpedite_gp(void) -{ -} -#else /* #ifdef CONFIG_TINY_RCU */ -bool rcu_gp_is_normal(void); /* Internal RCU use. */ -bool rcu_gp_is_expedited(void); /* Internal RCU use. */ -void rcu_expedite_gp(void); -void rcu_unexpedite_gp(void); -#endif /* #else #ifdef CONFIG_TINY_RCU */ - -enum rcutorture_type { - RCU_FLAVOR, - RCU_BH_FLAVOR, - RCU_SCHED_FLAVOR, - RCU_TASKS_FLAVOR, - SRCU_FLAVOR, - INVALID_RCU_FLAVOR -}; - -#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) -void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags, - unsigned long *gpnum, unsigned long *completed); -void rcutorture_record_test_transition(void); -void rcutorture_record_progress(unsigned long vernum); -void do_trace_rcu_torture_read(const char *rcutorturename, - struct rcu_head *rhp, - unsigned long secs, - unsigned long c_old, - unsigned long c); -bool rcu_irq_enter_disabled(void); -#else -static inline void rcutorture_get_gp_data(enum rcutorture_type test_type, - int *flags, - unsigned long *gpnum, - unsigned long *completed) -{ - *flags = 0; - *gpnum = 0; - *completed = 0; -} -static inline void rcutorture_record_test_transition(void) -{ -} -static inline void rcutorture_record_progress(unsigned long vernum) -{ -} -static inline bool rcu_irq_enter_disabled(void) -{ - return false; -} -#ifdef CONFIG_RCU_TRACE -void do_trace_rcu_torture_read(const char *rcutorturename, - struct rcu_head *rhp, - unsigned long secs, - unsigned long c_old, - unsigned long c); -#else -#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ - do { } while (0) -#endif -#endif - -#define UINT_CMP_GE(a, b) (UINT_MAX / 2 >= (a) - (b)) -#define UINT_CMP_LT(a, b) (UINT_MAX / 2 < (a) - (b)) #define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b)) #define ULONG_CMP_LT(a, b) (ULONG_MAX / 2 < (a) - (b)) #define ulong2long(a) (*(long *)(&(a))) @@ -139,117 +50,14 @@ void do_trace_rcu_torture_read(const char *rcutorturename, /* Exported common interfaces */ #ifdef CONFIG_PREEMPT_RCU - -/** - * call_rcu() - Queue an RCU callback for invocation after a grace period. - * @head: structure to be used for queueing the RCU updates. - * @func: actual callback function to be invoked after the grace period - * - * The callback function will be invoked some time after a full grace - * period elapses, in other words after all pre-existing RCU read-side - * critical sections have completed. However, the callback function - * might well execute concurrently with RCU read-side critical sections - * that started after call_rcu() was invoked. RCU read-side critical - * sections are delimited by rcu_read_lock() and rcu_read_unlock(), - * and may be nested. - * - * Note that all CPUs must agree that the grace period extended beyond - * all pre-existing RCU read-side critical section. On systems with more - * than one CPU, this means that when "func()" is invoked, each CPU is - * guaranteed to have executed a full memory barrier since the end of its - * last RCU read-side critical section whose beginning preceded the call - * to call_rcu(). It also means that each CPU executing an RCU read-side - * critical section that continues beyond the start of "func()" must have - * executed a memory barrier after the call_rcu() but before the beginning - * of that RCU read-side critical section. Note that these guarantees - * include CPUs that are offline, idle, or executing in user mode, as - * well as CPUs that are executing in the kernel. - * - * Furthermore, if CPU A invoked call_rcu() and CPU B invoked the - * resulting RCU callback function "func()", then both CPU A and CPU B are - * guaranteed to execute a full memory barrier during the time interval - * between the call to call_rcu() and the invocation of "func()" -- even - * if CPU A and CPU B are the same CPU (but again only if the system has - * more than one CPU). - */ -void call_rcu(struct rcu_head *head, - rcu_callback_t func); - +void call_rcu(struct rcu_head *head, rcu_callback_t func); #else /* #ifdef CONFIG_PREEMPT_RCU */ - -/* In classic RCU, call_rcu() is just call_rcu_sched(). */ #define call_rcu call_rcu_sched - #endif /* #else #ifdef CONFIG_PREEMPT_RCU */ -/** - * call_rcu_bh() - Queue an RCU for invocation after a quicker grace period. - * @head: structure to be used for queueing the RCU updates. - * @func: actual callback function to be invoked after the grace period - * - * The callback function will be invoked some time after a full grace - * period elapses, in other words after all currently executing RCU - * read-side critical sections have completed. call_rcu_bh() assumes - * that the read-side critical sections end on completion of a softirq - * handler. This means that read-side critical sections in process - * context must not be interrupted by softirqs. This interface is to be - * used when most of the read-side critical sections are in softirq context. - * RCU read-side critical sections are delimited by : - * - rcu_read_lock() and rcu_read_unlock(), if in interrupt context. - * OR - * - rcu_read_lock_bh() and rcu_read_unlock_bh(), if in process context. - * These may be nested. - * - * See the description of call_rcu() for more detailed information on - * memory ordering guarantees. - */ -void call_rcu_bh(struct rcu_head *head, - rcu_callback_t func); - -/** - * call_rcu_sched() - Queue an RCU for invocation after sched grace period. - * @head: structure to be used for queueing the RCU updates. - * @func: actual callback function to be invoked after the grace period - * - * The callback function will be invoked some time after a full grace - * period elapses, in other words after all currently executing RCU - * read-side critical sections have completed. call_rcu_sched() assumes - * that the read-side critical sections end on enabling of preemption - * or on voluntary preemption. - * RCU read-side critical sections are delimited by : - * - rcu_read_lock_sched() and rcu_read_unlock_sched(), - * OR - * anything that disables preemption. - * These may be nested. - * - * See the description of call_rcu() for more detailed information on - * memory ordering guarantees. - */ -void call_rcu_sched(struct rcu_head *head, - rcu_callback_t func); - +void call_rcu_bh(struct rcu_head *head, rcu_callback_t func); +void call_rcu_sched(struct rcu_head *head, rcu_callback_t func); void synchronize_sched(void); - -/** - * call_rcu_tasks() - Queue an RCU for invocation task-based grace period - * @head: structure to be used for queueing the RCU updates. - * @func: actual callback function to be invoked after the grace period - * - * The callback function will be invoked some time after a full grace - * period elapses, in other words after all currently executing RCU - * read-side critical sections have completed. call_rcu_tasks() assumes - * that the read-side critical sections end at a voluntary context - * switch (not a preemption!), entry into idle, or transition to usermode - * execution. As such, there are no read-side primitives analogous to - * rcu_read_lock() and rcu_read_unlock() because this primitive is intended - * to determine that all tasks have passed through a safe state, not so - * much for data-strcuture synchronization. - * - * See the description of call_rcu() for more detailed information on - * memory ordering guarantees. - */ -void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func); -void synchronize_rcu_tasks(void); void rcu_barrier_tasks(void); #ifdef CONFIG_PREEMPT_RCU @@ -295,28 +103,20 @@ static inline int rcu_preempt_depth(void) /* Internal to kernel */ void rcu_init(void); +extern int rcu_scheduler_active __read_mostly; void rcu_sched_qs(void); void rcu_bh_qs(void); void rcu_check_callbacks(int user); void rcu_report_dead(unsigned int cpu); void rcu_cpu_starting(unsigned int cpu); - -#ifndef CONFIG_TINY_RCU -void rcu_end_inkernel_boot(void); -#else /* #ifndef CONFIG_TINY_RCU */ -static inline void rcu_end_inkernel_boot(void) { } -#endif /* #ifndef CONFIG_TINY_RCU */ +void rcutree_migrate_callbacks(int cpu); #ifdef CONFIG_RCU_STALL_COMMON void rcu_sysrq_start(void); void rcu_sysrq_end(void); #else /* #ifdef CONFIG_RCU_STALL_COMMON */ -static inline void rcu_sysrq_start(void) -{ -} -static inline void rcu_sysrq_end(void) -{ -} +static inline void rcu_sysrq_start(void) { } +static inline void rcu_sysrq_end(void) { } #endif /* #else #ifdef CONFIG_RCU_STALL_COMMON */ #ifdef CONFIG_NO_HZ_FULL @@ -330,9 +130,7 @@ static inline void rcu_user_exit(void) { } #ifdef CONFIG_RCU_NOCB_CPU void rcu_init_nohz(void); #else /* #ifdef CONFIG_RCU_NOCB_CPU */ -static inline void rcu_init_nohz(void) -{ -} +static inline void rcu_init_nohz(void) { } #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ /** @@ -366,8 +164,6 @@ static inline void rcu_init_nohz(void) * macro rather than an inline function to avoid #include hell. */ #ifdef CONFIG_TASKS_RCU -#define TASKS_RCU(x) x -extern struct srcu_struct tasks_rcu_exit_srcu; #define rcu_note_voluntary_context_switch_lite(t) \ do { \ if (READ_ONCE((t)->rcu_tasks_holdout)) \ @@ -378,10 +174,17 @@ extern struct srcu_struct tasks_rcu_exit_srcu; rcu_all_qs(); \ rcu_note_voluntary_context_switch_lite(t); \ } while (0) +void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func); +void synchronize_rcu_tasks(void); +void exit_tasks_rcu_start(void); +void exit_tasks_rcu_finish(void); #else /* #ifdef CONFIG_TASKS_RCU */ -#define TASKS_RCU(x) do { } while (0) #define rcu_note_voluntary_context_switch_lite(t) do { } while (0) #define rcu_note_voluntary_context_switch(t) rcu_all_qs() +#define call_rcu_tasks call_rcu_sched +#define synchronize_rcu_tasks synchronize_sched +static inline void exit_tasks_rcu_start(void) { } +static inline void exit_tasks_rcu_finish(void) { } #endif /* #else #ifdef CONFIG_TASKS_RCU */ /** @@ -397,10 +200,6 @@ do { \ rcu_note_voluntary_context_switch(current); \ } while (0) -#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) || defined(CONFIG_SMP) -bool __rcu_is_watching(void); -#endif /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) || defined(CONFIG_SMP) */ - /* * Infrastructure to implement the synchronize_() primitives in * TREE_RCU and rcu_barrier_() primitives in TINY_RCU. @@ -414,10 +213,6 @@ bool __rcu_is_watching(void); #error "Unknown RCU implementation specified to kernel configuration" #endif -#define RCU_SCHEDULER_INACTIVE 0 -#define RCU_SCHEDULER_INIT 1 -#define RCU_SCHEDULER_RUNNING 2 - /* * init_rcu_head_on_stack()/destroy_rcu_head_on_stack() are needed for dynamic * initialization and destruction of rcu_head on the stack. rcu_head structures @@ -430,30 +225,16 @@ void destroy_rcu_head(struct rcu_head *head); void init_rcu_head_on_stack(struct rcu_head *head); void destroy_rcu_head_on_stack(struct rcu_head *head); #else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ -static inline void init_rcu_head(struct rcu_head *head) -{ -} - -static inline void destroy_rcu_head(struct rcu_head *head) -{ -} - -static inline void init_rcu_head_on_stack(struct rcu_head *head) -{ -} - -static inline void destroy_rcu_head_on_stack(struct rcu_head *head) -{ -} +static inline void init_rcu_head(struct rcu_head *head) { } +static inline void destroy_rcu_head(struct rcu_head *head) { } +static inline void init_rcu_head_on_stack(struct rcu_head *head) { } +static inline void destroy_rcu_head_on_stack(struct rcu_head *head) { } #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ #if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PROVE_RCU) bool rcu_lockdep_current_cpu_online(void); #else /* #if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PROVE_RCU) */ -static inline bool rcu_lockdep_current_cpu_online(void) -{ - return true; -} +static inline bool rcu_lockdep_current_cpu_online(void) { return true; } #endif /* #else #if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PROVE_RCU) */ #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -473,18 +254,8 @@ extern struct lockdep_map rcu_bh_lock_map; extern struct lockdep_map rcu_sched_lock_map; extern struct lockdep_map rcu_callback_map; int debug_lockdep_rcu_enabled(void); - int rcu_read_lock_held(void); int rcu_read_lock_bh_held(void); - -/** - * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section? - * - * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns 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. - */ int rcu_read_lock_sched_held(void); #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ @@ -531,9 +302,7 @@ static inline void rcu_preempt_sleep_check(void) "Illegal context switch in RCU read-side critical section"); } #else /* #ifdef CONFIG_PROVE_RCU */ -static inline void rcu_preempt_sleep_check(void) -{ -} +static inline void rcu_preempt_sleep_check(void) { } #endif /* #else #ifdef CONFIG_PROVE_RCU */ #define rcu_sleep_check() \ @@ -644,6 +413,22 @@ static inline void rcu_preempt_sleep_check(void) }) /** + * rcu_swap_protected() - swap an RCU and a regular pointer + * @rcu_ptr: RCU pointer + * @ptr: regular pointer + * @c: the conditions under which the dereference will take place + * + * Perform swap(@rcu_ptr, @ptr) where @rcu_ptr is an RCU-annotated pointer and + * @c is the argument that is passed to the rcu_dereference_protected() call + * used to read that pointer. + */ +#define rcu_swap_protected(rcu_ptr, ptr, c) do { \ + typeof(ptr) __tmp = rcu_dereference_protected((rcu_ptr), (c)); \ + rcu_assign_pointer((rcu_ptr), (ptr)); \ + (ptr) = __tmp; \ +} while (0) + +/** * rcu_access_pointer() - fetch RCU pointer with no dereferencing * @p: The pointer to read * @@ -738,7 +523,7 @@ static inline void rcu_preempt_sleep_check(void) * Return the value of the specified RCU-protected pointer, but omit * both the smp_read_barrier_depends() and the READ_ONCE(). This * is useful in cases where update-side locks prevent the value of the - * pointer from changing. Please note that this primitive does -not- + * pointer from changing. Please note that this primitive does *not* * prevent the compiler from repeating this reference or combining it * with other references, so it should not be used without protection * of appropriate locks. @@ -783,7 +568,7 @@ static inline void rcu_preempt_sleep_check(void) * is handed off from RCU to some other synchronization mechanism, for * example, reference counting or locking. In C11, it would map to * kill_dependency(). It could be used as follows: - * + * `` * rcu_read_lock(); * p = rcu_dereference(gp); * long_lived = is_long_lived(p); @@ -794,6 +579,7 @@ static inline void rcu_preempt_sleep_check(void) * p = rcu_pointer_handoff(p); * } * rcu_read_unlock(); + *`` */ #define rcu_pointer_handoff(p) (p) @@ -993,18 +779,21 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) /** * RCU_INIT_POINTER() - initialize an RCU protected pointer + * @p: The pointer to be initialized. + * @v: The value to initialized the pointer to. * * Initialize an RCU-protected pointer in special cases where readers * do not need ordering constraints on the CPU or the compiler. These * special cases are: * - * 1. This use of RCU_INIT_POINTER() is NULLing out the pointer -or- + * 1. This use of RCU_INIT_POINTER() is NULLing out the pointer *or* * 2. The caller has taken whatever steps are required to prevent - * RCU readers from concurrently accessing this pointer -or- + * RCU readers from concurrently accessing this pointer *or* * 3. The referenced data structure has already been exposed to - * readers either at compile time or via rcu_assign_pointer() -and- - * a. You have not made -any- reader-visible changes to - * this structure since then -or- + * readers either at compile time or via rcu_assign_pointer() *and* + * + * a. You have not made *any* reader-visible changes to + * this structure since then *or* * b. It is OK for readers accessing this structure from its * new location to see the old state of the structure. (For * example, the changes were to statistical counters or to @@ -1020,7 +809,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) * by a single external-to-structure RCU-protected pointer, then you may * use RCU_INIT_POINTER() to initialize the internal RCU-protected * pointers, but you must use rcu_assign_pointer() to initialize the - * external-to-structure pointer -after- you have completely initialized + * external-to-structure pointer *after* you have completely initialized * the reader-accessible portions of the linked structure. * * Note that unlike rcu_assign_pointer(), RCU_INIT_POINTER() provides no @@ -1034,6 +823,8 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) /** * RCU_POINTER_INITIALIZER() - statically initialize an RCU protected pointer + * @p: The pointer to be initialized. + * @v: The value to initialized the pointer to. * * GCC-style initialization for an RCU-protected pointer in a structure field. */ @@ -1084,52 +875,6 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) #define kfree_rcu(ptr, rcu_head) \ __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) -#ifdef CONFIG_TINY_RCU -static inline int rcu_needs_cpu(u64 basemono, u64 *nextevt) -{ - *nextevt = KTIME_MAX; - return 0; -} -#endif /* #ifdef CONFIG_TINY_RCU */ - -#if defined(CONFIG_RCU_NOCB_CPU_ALL) -static inline bool rcu_is_nocb_cpu(int cpu) { return true; } -#elif defined(CONFIG_RCU_NOCB_CPU) -bool rcu_is_nocb_cpu(int cpu); -#else -static inline bool rcu_is_nocb_cpu(int cpu) { return false; } -#endif - - -/* Only for use by adaptive-ticks code. */ -#ifdef CONFIG_NO_HZ_FULL_SYSIDLE -bool rcu_sys_is_idle(void); -void rcu_sysidle_force_exit(void); -#else /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */ - -static inline bool rcu_sys_is_idle(void) -{ - return false; -} - -static inline void rcu_sysidle_force_exit(void) -{ -} - -#endif /* #else #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */ - - -/* - * Dump the ftrace buffer, but only one time per callsite per boot. - */ -#define rcu_ftrace_dump(oops_dump_mode) \ -do { \ - static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \ - \ - if (!atomic_read(&___rfd_beenhere) && \ - !atomic_xchg(&___rfd_beenhere, 1)) \ - ftrace_dump(oops_dump_mode); \ -} while (0) /* * Place this after a lock-acquisition primitive to guarantee that |