diff options
Diffstat (limited to 'include/linux/rcupdate.h')
| -rw-r--r-- | include/linux/rcupdate.h | 370 |
1 files changed, 263 insertions, 107 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 2678a37c3169..08605ce7379d 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -29,16 +29,45 @@ #include <linux/lockdep.h> #include <asm/processor.h> #include <linux/cpumask.h> +#include <linux/context_tracking_irq.h> #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))) +#define USHORT_CMP_GE(a, b) (USHRT_MAX / 2 >= (unsigned short)((a) - (b))) +#define USHORT_CMP_LT(a, b) (USHRT_MAX / 2 < (unsigned short)((a) - (b))) /* Exported common interfaces */ void call_rcu(struct rcu_head *head, rcu_callback_t func); void rcu_barrier_tasks(void); +void rcu_barrier_tasks_rude(void); void synchronize_rcu(void); +struct rcu_gp_oldstate; +unsigned long get_completed_synchronize_rcu(void); +void get_completed_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp); + +// Maximum number of unsigned long values corresponding to +// not-yet-completed RCU grace periods. +#define NUM_ACTIVE_RCU_POLL_OLDSTATE 2 + +/** + * same_state_synchronize_rcu - Are two old-state values identical? + * @oldstate1: First old-state value. + * @oldstate2: Second old-state value. + * + * The two old-state values must have been obtained from either + * get_state_synchronize_rcu(), start_poll_synchronize_rcu(), or + * get_completed_synchronize_rcu(). Returns @true if the two values are + * identical and @false otherwise. This allows structures whose lifetimes + * are tracked by old-state values to push these values to a list header, + * allowing those structures to be slightly smaller. + */ +static inline bool same_state_synchronize_rcu(unsigned long oldstate1, unsigned long oldstate2) +{ + return oldstate1 == oldstate2; +} + #ifdef CONFIG_PREEMPT_RCU void __rcu_read_lock(void); @@ -50,10 +79,16 @@ void __rcu_read_unlock(void); * nesting depth, but makes sense only if CONFIG_PREEMPT_RCU -- in other * types of kernel builds, the rcu_read_lock() nesting depth is unknowable. */ -#define rcu_preempt_depth() (current->rcu_read_lock_nesting) +#define rcu_preempt_depth() READ_ONCE(current->rcu_read_lock_nesting) #else /* #ifdef CONFIG_PREEMPT_RCU */ +#ifdef CONFIG_TINY_RCU +#define rcu_read_unlock_strict() do { } while (0) +#else +void rcu_read_unlock_strict(void); +#endif + static inline void __rcu_read_lock(void) { preempt_disable(); @@ -62,6 +97,8 @@ static inline void __rcu_read_lock(void) static inline void __rcu_read_unlock(void) { preempt_enable(); + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) + rcu_read_unlock_strict(); } static inline int rcu_preempt_depth(void) @@ -73,11 +110,17 @@ static inline int rcu_preempt_depth(void) /* Internal to kernel */ void rcu_init(void); -extern int rcu_scheduler_active __read_mostly; +extern int rcu_scheduler_active; void rcu_sched_clock_irq(int user); void rcu_report_dead(unsigned int cpu); void rcutree_migrate_callbacks(int cpu); +#ifdef CONFIG_TASKS_RCU_GENERIC +void rcu_init_tasks_generic(void); +#else +static inline void rcu_init_tasks_generic(void) { } +#endif + #ifdef CONFIG_RCU_STALL_COMMON void rcu_sysrq_start(void); void rcu_sysrq_end(void); @@ -86,18 +129,22 @@ 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 -void rcu_user_enter(void); -void rcu_user_exit(void); +#if defined(CONFIG_NO_HZ_FULL) && (!defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_TO_GUEST_WORK)) +void rcu_irq_work_resched(void); #else -static inline void rcu_user_enter(void) { } -static inline void rcu_user_exit(void) { } -#endif /* CONFIG_NO_HZ_FULL */ +static inline void rcu_irq_work_resched(void) { } +#endif #ifdef CONFIG_RCU_NOCB_CPU void rcu_init_nohz(void); +int rcu_nocb_cpu_offload(int cpu); +int rcu_nocb_cpu_deoffload(int cpu); +void rcu_nocb_flush_deferred_wakeup(void); #else /* #ifdef CONFIG_RCU_NOCB_CPU */ static inline void rcu_init_nohz(void) { } +static inline int rcu_nocb_cpu_offload(int cpu) { return -EINVAL; } +static inline int rcu_nocb_cpu_deoffload(int cpu) { return 0; } +static inline void rcu_nocb_flush_deferred_wakeup(void) { } #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ /** @@ -105,7 +152,7 @@ static inline void rcu_init_nohz(void) { } * @a: Code that RCU needs to pay attention to. * * RCU read-side critical sections are forbidden in the inner idle loop, - * that is, between the rcu_idle_enter() and the rcu_idle_exit() -- RCU + * that is, between the ct_idle_enter() and the ct_idle_exit() -- RCU * will happily ignore any such read-side critical sections. However, * things like powertop need tracepoints in the inner idle loop. * @@ -120,34 +167,78 @@ static inline void rcu_init_nohz(void) { } */ #define RCU_NONIDLE(a) \ do { \ - rcu_irq_enter_irqson(); \ + ct_irq_enter_irqson(); \ do { a; } while (0); \ - rcu_irq_exit_irqson(); \ + ct_irq_exit_irqson(); \ } while (0) /* * Note a quasi-voluntary context switch for RCU-tasks's benefit. * This is a macro rather than an inline function to avoid #include hell. */ -#ifdef CONFIG_TASKS_RCU -#define rcu_tasks_qs(t) \ - do { \ - if (READ_ONCE((t)->rcu_tasks_holdout)) \ - WRITE_ONCE((t)->rcu_tasks_holdout, false); \ +#ifdef CONFIG_TASKS_RCU_GENERIC + +# ifdef CONFIG_TASKS_RCU +# define rcu_tasks_classic_qs(t, preempt) \ + do { \ + if (!(preempt) && READ_ONCE((t)->rcu_tasks_holdout)) \ + WRITE_ONCE((t)->rcu_tasks_holdout, false); \ } while (0) -#define rcu_note_voluntary_context_switch(t) rcu_tasks_qs(t) void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func); void synchronize_rcu_tasks(void); +# else +# define rcu_tasks_classic_qs(t, preempt) do { } while (0) +# define call_rcu_tasks call_rcu +# define synchronize_rcu_tasks synchronize_rcu +# endif + +# ifdef CONFIG_TASKS_TRACE_RCU +// Bits for ->trc_reader_special.b.need_qs field. +#define TRC_NEED_QS 0x1 // Task needs a quiescent state. +#define TRC_NEED_QS_CHECKED 0x2 // Task has been checked for needing quiescent state. + +u8 rcu_trc_cmpxchg_need_qs(struct task_struct *t, u8 old, u8 new); +void rcu_tasks_trace_qs_blkd(struct task_struct *t); + +# define rcu_tasks_trace_qs(t) \ + do { \ + int ___rttq_nesting = READ_ONCE((t)->trc_reader_nesting); \ + \ + if (likely(!READ_ONCE((t)->trc_reader_special.b.need_qs)) && \ + likely(!___rttq_nesting)) { \ + rcu_trc_cmpxchg_need_qs((t), 0, TRC_NEED_QS_CHECKED); \ + } else if (___rttq_nesting && ___rttq_nesting != INT_MIN && \ + !READ_ONCE((t)->trc_reader_special.b.blocked)) { \ + rcu_tasks_trace_qs_blkd(t); \ + } \ + } while (0) +# else +# define rcu_tasks_trace_qs(t) do { } while (0) +# endif + +#define rcu_tasks_qs(t, preempt) \ +do { \ + rcu_tasks_classic_qs((t), (preempt)); \ + rcu_tasks_trace_qs(t); \ +} while (0) + +# ifdef CONFIG_TASKS_RUDE_RCU +void call_rcu_tasks_rude(struct rcu_head *head, rcu_callback_t func); +void synchronize_rcu_tasks_rude(void); +# endif + +#define rcu_note_voluntary_context_switch(t) rcu_tasks_qs(t, false) void exit_tasks_rcu_start(void); void exit_tasks_rcu_finish(void); -#else /* #ifdef CONFIG_TASKS_RCU */ -#define rcu_tasks_qs(t) do { } while (0) +#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */ +#define rcu_tasks_classic_qs(t, preempt) do { } while (0) +#define rcu_tasks_qs(t, preempt) do { } while (0) #define rcu_note_voluntary_context_switch(t) do { } while (0) #define call_rcu_tasks call_rcu #define synchronize_rcu_tasks synchronize_rcu static inline void exit_tasks_rcu_start(void) { } static inline void exit_tasks_rcu_finish(void) { } -#endif /* #else #ifdef CONFIG_TASKS_RCU */ +#endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */ /** * cond_resched_tasks_rcu_qs - Report potential quiescent states to RCU @@ -158,7 +249,7 @@ static inline void exit_tasks_rcu_finish(void) { } */ #define cond_resched_tasks_rcu_qs() \ do { \ - rcu_tasks_qs(current); \ + rcu_tasks_qs(current, false); \ cond_resched(); \ } while (0) @@ -201,6 +292,11 @@ bool rcu_lockdep_current_cpu_online(void); static inline bool rcu_lockdep_current_cpu_online(void) { return true; } #endif /* #else #if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PROVE_RCU) */ +extern struct lockdep_map rcu_lock_map; +extern struct lockdep_map rcu_bh_lock_map; +extern struct lockdep_map rcu_sched_lock_map; +extern struct lockdep_map rcu_callback_map; + #ifdef CONFIG_DEBUG_LOCK_ALLOC static inline void rcu_lock_acquire(struct lockdep_map *map) @@ -213,10 +309,6 @@ static inline void rcu_lock_release(struct lockdep_map *map) lock_release(map, _THIS_IP_); } -extern struct lockdep_map rcu_lock_map; -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); @@ -259,8 +351,8 @@ static inline int rcu_read_lock_any_held(void) */ #define RCU_LOCKDEP_WARN(c, s) \ do { \ - static bool __section(.data.unlikely) __warned; \ - if (debug_lockdep_rcu_enabled() && !__warned && (c)) { \ + static bool __section(".data.unlikely") __warned; \ + if ((c) && debug_lockdep_rcu_enabled() && !__warned) { \ __warned = true; \ lockdep_rcu_suspicious(__FILE__, __LINE__, s); \ } \ @@ -279,7 +371,8 @@ static inline void rcu_preempt_sleep_check(void) { } #define rcu_sleep_check() \ do { \ rcu_preempt_sleep_check(); \ - RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map), \ + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) \ + RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map), \ "Illegal context switch in RCU-bh read-side critical section"); \ RCU_LOCKDEP_WARN(lock_is_held(&rcu_sched_lock_map), \ "Illegal context switch in RCU-sched read-side critical section"); \ @@ -287,7 +380,7 @@ static inline void rcu_preempt_sleep_check(void) { } #else /* #ifdef CONFIG_PROVE_RCU */ -#define RCU_LOCKDEP_WARN(c, s) do { } while (0) +#define RCU_LOCKDEP_WARN(c, s) do { } while (0 && (c)) #define rcu_sleep_check() do { } while (0) #endif /* #else #ifdef CONFIG_PROVE_RCU */ @@ -307,32 +400,48 @@ static inline void rcu_preempt_sleep_check(void) { } #define rcu_check_sparse(p, space) #endif /* #else #ifdef __CHECKER__ */ -#define __rcu_access_pointer(p, space) \ +#define __unrcu_pointer(p, local) \ +({ \ + typeof(*p) *local = (typeof(*p) *__force)(p); \ + rcu_check_sparse(p, __rcu); \ + ((typeof(*p) __force __kernel *)(local)); \ +}) +/** + * unrcu_pointer - mark a pointer as not being RCU protected + * @p: pointer needing to lose its __rcu property + * + * Converts @p from an __rcu pointer to a __kernel pointer. + * This allows an __rcu pointer to be used with xchg() and friends. + */ +#define unrcu_pointer(p) __unrcu_pointer(p, __UNIQUE_ID(rcu)) + +#define __rcu_access_pointer(p, local, space) \ ({ \ - typeof(*p) *_________p1 = (typeof(*p) *__force)READ_ONCE(p); \ + typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \ rcu_check_sparse(p, space); \ - ((typeof(*p) __force __kernel *)(_________p1)); \ + ((typeof(*p) __force __kernel *)(local)); \ }) -#define __rcu_dereference_check(p, c, space) \ +#define __rcu_dereference_check(p, local, c, space) \ ({ \ /* Dependency order vs. p above. */ \ - typeof(*p) *________p1 = (typeof(*p) *__force)READ_ONCE(p); \ + typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \ RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_check() usage"); \ rcu_check_sparse(p, space); \ - ((typeof(*p) __force __kernel *)(________p1)); \ + ((typeof(*p) __force __kernel *)(local)); \ }) -#define __rcu_dereference_protected(p, c, space) \ +#define __rcu_dereference_protected(p, local, c, space) \ ({ \ RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_protected() usage"); \ rcu_check_sparse(p, space); \ ((typeof(*p) __force __kernel *)(p)); \ }) -#define rcu_dereference_raw(p) \ +#define __rcu_dereference_raw(p, local) \ ({ \ /* Dependency order vs. p above. */ \ - typeof(p) ________p1 = READ_ONCE(p); \ - ((typeof(*p) __force __kernel *)(________p1)); \ + typeof(p) local = READ_ONCE(p); \ + ((typeof(*p) __force __kernel *)(local)); \ }) +#define rcu_dereference_raw(p) __rcu_dereference_raw(p, __UNIQUE_ID(rcu)) /** * RCU_INITIALIZER() - statically initialize an RCU-protected global variable @@ -411,15 +520,23 @@ do { \ * against NULL. Although rcu_access_pointer() may also be used in cases * where update-side locks prevent the value of the pointer from changing, * you should instead use rcu_dereference_protected() for this use case. + * Within an RCU read-side critical section, there is little reason to + * use rcu_access_pointer(). + * + * It is usually best to test the rcu_access_pointer() return value + * directly in order to avoid accidental dereferences being introduced + * by later inattentive changes. In other words, assigning the + * rcu_access_pointer() return value to a local variable results in an + * accident waiting to happen. * * It is also permissible to use rcu_access_pointer() when read-side - * access to the pointer was removed at least one grace period ago, as - * is the case in the context of the RCU callback that is freeing up - * the data, or after a synchronize_rcu() returns. This can be useful - * when tearing down multi-linked structures after a grace period - * has elapsed. + * access to the pointer was removed at least one grace period ago, as is + * the case in the context of the RCU callback that is freeing up the data, + * or after a synchronize_rcu() returns. This can be useful when tearing + * down multi-linked structures after a grace period has elapsed. However, + * rcu_dereference_protected() is normally preferred for this use case. */ -#define rcu_access_pointer(p) __rcu_access_pointer((p), __rcu) +#define rcu_access_pointer(p) __rcu_access_pointer((p), __UNIQUE_ID(rcu), __rcu) /** * rcu_dereference_check() - rcu_dereference with debug checking @@ -455,17 +572,24 @@ do { \ * annotated as __rcu. */ #define rcu_dereference_check(p, c) \ - __rcu_dereference_check((p), (c) || rcu_read_lock_held(), __rcu) + __rcu_dereference_check((p), __UNIQUE_ID(rcu), \ + (c) || rcu_read_lock_held(), __rcu) /** * rcu_dereference_bh_check() - rcu_dereference_bh with debug checking * @p: The pointer to read, prior to dereferencing * @c: The conditions under which the dereference will take place * - * This is the RCU-bh counterpart to rcu_dereference_check(). + * This is the RCU-bh counterpart to rcu_dereference_check(). However, + * please note that starting in v5.0 kernels, vanilla RCU grace periods + * wait for local_bh_disable() regions of code in addition to regions of + * code demarked by rcu_read_lock() and rcu_read_unlock(). This means + * that synchronize_rcu(), call_rcu, and friends all take not only + * rcu_read_lock() but also rcu_read_lock_bh() into account. */ #define rcu_dereference_bh_check(p, c) \ - __rcu_dereference_check((p), (c) || rcu_read_lock_bh_held(), __rcu) + __rcu_dereference_check((p), __UNIQUE_ID(rcu), \ + (c) || rcu_read_lock_bh_held(), __rcu) /** * rcu_dereference_sched_check() - rcu_dereference_sched with debug checking @@ -473,9 +597,15 @@ do { \ * @c: The conditions under which the dereference will take place * * This is the RCU-sched counterpart to rcu_dereference_check(). + * However, please note that starting in v5.0 kernels, vanilla RCU grace + * periods wait for preempt_disable() regions of code in addition to + * regions of code demarked by rcu_read_lock() and rcu_read_unlock(). + * This means that synchronize_rcu(), call_rcu, and friends all take not + * only rcu_read_lock() but also rcu_read_lock_sched() into account. */ #define rcu_dereference_sched_check(p, c) \ - __rcu_dereference_check((p), (c) || rcu_read_lock_sched_held(), \ + __rcu_dereference_check((p), __UNIQUE_ID(rcu), \ + (c) || rcu_read_lock_sched_held(), \ __rcu) /* @@ -485,7 +615,8 @@ do { \ * The no-tracing version of rcu_dereference_raw() must not call * rcu_read_lock_held(). */ -#define rcu_dereference_raw_check(p) __rcu_dereference_check((p), 1, __rcu) +#define rcu_dereference_raw_check(p) \ + __rcu_dereference_check((p), __UNIQUE_ID(rcu), 1, __rcu) /** * rcu_dereference_protected() - fetch RCU pointer when updates prevented @@ -504,7 +635,7 @@ do { \ * but very ugly failures. */ #define rcu_dereference_protected(p, c) \ - __rcu_dereference_protected((p), (c), __rcu) + __rcu_dereference_protected((p), __UNIQUE_ID(rcu), (c), __rcu) /** @@ -564,6 +695,12 @@ do { \ * sections, invocation of the corresponding RCU callback is deferred * until after the all the other CPUs exit their critical sections. * + * In v5.0 and later kernels, synchronize_rcu() and call_rcu() also + * wait for regions of code with preemption disabled, including regions of + * code with interrupts or softirqs disabled. In pre-v5.0 kernels, which + * define synchronize_sched(), only code enclosed within rcu_read_lock() + * and rcu_read_unlock() are guaranteed to be waited for. + * * Note, however, that RCU callbacks are permitted to run concurrently * with new RCU read-side critical sections. One way that this can happen * is via the following sequence of events: (1) CPU 0 enters an RCU @@ -616,33 +753,12 @@ static __always_inline void rcu_read_lock(void) /** * rcu_read_unlock() - marks the end of an RCU read-side critical section. * - * In most situations, rcu_read_unlock() is immune from deadlock. - * However, in kernels built with CONFIG_RCU_BOOST, rcu_read_unlock() - * is responsible for deboosting, which it does via rt_mutex_unlock(). - * Unfortunately, this function acquires the scheduler's runqueue and - * priority-inheritance spinlocks. This means that deadlock could result - * if the caller of rcu_read_unlock() already holds one of these locks or - * any lock that is ever acquired while holding them. - * - * That said, RCU readers are never priority boosted unless they were - * preempted. Therefore, one way to avoid deadlock is to make sure - * that preemption never happens within any RCU read-side critical - * section whose outermost rcu_read_unlock() is called with one of - * rt_mutex_unlock()'s locks held. Such preemption can be avoided in - * a number of ways, for example, by invoking preempt_disable() before - * critical section's outermost rcu_read_lock(). - * - * Given that the set of locks acquired by rt_mutex_unlock() might change - * at any time, a somewhat more future-proofed approach is to make sure - * that that preemption never happens within any RCU read-side critical - * section whose outermost rcu_read_unlock() is called with irqs disabled. - * This approach relies on the fact that rt_mutex_unlock() currently only - * acquires irq-disabled locks. - * - * The second of these two approaches is best in most situations, - * however, the first approach can also be useful, at least to those - * developers willing to keep abreast of the set of locks acquired by - * rt_mutex_unlock(). + * In almost all situations, rcu_read_unlock() is immune from deadlock. + * In recent kernels that have consolidated synchronize_sched() and + * synchronize_rcu_bh() into synchronize_rcu(), this deadlock immunity + * also extends to the scheduler's runqueue and priority-inheritance + * spinlocks, courtesy of the quiescent-state deferral that is carried + * out when rcu_read_unlock() is invoked with interrupts disabled. * * See rcu_read_lock() for more information. */ @@ -658,9 +774,11 @@ static inline void rcu_read_unlock(void) /** * rcu_read_lock_bh() - mark the beginning of an RCU-bh critical section * - * This is equivalent of rcu_read_lock(), but also disables softirqs. - * Note that anything else that disables softirqs can also serve as - * an RCU read-side critical section. + * This is equivalent to rcu_read_lock(), but also disables softirqs. + * Note that anything else that disables softirqs can also serve as an RCU + * read-side critical section. However, please note that this equivalence + * applies only to v5.0 and later. Before v5.0, rcu_read_lock() and + * rcu_read_lock_bh() were unrelated. * * Note that rcu_read_lock_bh() and the matching rcu_read_unlock_bh() * must occur in the same context, for example, it is illegal to invoke @@ -676,8 +794,8 @@ static inline void rcu_read_lock_bh(void) "rcu_read_lock_bh() used illegally while idle"); } -/* - * rcu_read_unlock_bh - marks the end of a softirq-only RCU critical section +/** + * rcu_read_unlock_bh() - marks the end of a softirq-only RCU critical section * * See rcu_read_lock_bh() for more information. */ @@ -693,9 +811,12 @@ static inline void rcu_read_unlock_bh(void) /** * rcu_read_lock_sched() - mark the beginning of a RCU-sched critical section * - * This is equivalent of rcu_read_lock(), but disables preemption. - * Read-side critical sections can also be introduced by anything else - * that disables preemption, including local_irq_disable() and friends. + * This is equivalent to rcu_read_lock(), but also disables preemption. + * Read-side critical sections can also be introduced by anything else that + * disables preemption, including local_irq_disable() and friends. However, + * please note that the equivalence to rcu_read_lock() applies only to + * v5.0 and later. Before v5.0, rcu_read_lock() and rcu_read_lock_sched() + * were unrelated. * * Note that rcu_read_lock_sched() and the matching rcu_read_unlock_sched() * must occur in the same context, for example, it is illegal to invoke @@ -718,10 +839,10 @@ static inline notrace void rcu_read_lock_sched_notrace(void) __acquire(RCU_SCHED); } -/* - * rcu_read_unlock_sched - marks the end of a RCU-classic critical section +/** + * rcu_read_unlock_sched() - marks the end of a RCU-classic critical section * - * See rcu_read_lock_sched for more information. + * See rcu_read_lock_sched() for more information. */ static inline void rcu_read_unlock_sched(void) { @@ -795,23 +916,15 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) /* * Does the specified offset indicate that the corresponding rcu_head - * structure can be handled by kfree_rcu()? + * structure can be handled by kvfree_rcu()? */ -#define __is_kfree_rcu_offset(offset) ((offset) < 4096) - -/* - * Helper macro for kfree_rcu() to prevent argument-expansion eyestrain. - */ -#define __kfree_rcu(head, offset) \ - do { \ - BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); \ - kfree_call_rcu(head, (rcu_callback_t)(unsigned long)(offset)); \ - } while (0) +#define __is_kvfree_rcu_offset(offset) ((offset) < 4096) /** * kfree_rcu() - kfree an object after a grace period. - * @ptr: pointer to kfree - * @rhf: the name of the struct rcu_head within the type of @ptr. + * @ptr: pointer to kfree for both single- and double-argument invocations. + * @rhf: the name of the struct rcu_head within the type of @ptr, + * but only for double-argument invocations. * * Many rcu callbacks functions just call kfree() on the base structure. * These functions are trivial, but their size adds up, and furthermore @@ -824,7 +937,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) * Because the functions are not allowed in the low-order 4096 bytes of * kernel virtual memory, offsets up to 4095 bytes can be accommodated. * If the offset is larger than 4095 bytes, a compile-time error will - * be generated in __kfree_rcu(). If this error is triggered, you can + * be generated in kvfree_rcu_arg_2(). If this error is triggered, you can * either fall back to use of call_rcu() or rearrange the structure to * position the rcu_head structure into the first 4096 bytes. * @@ -834,12 +947,55 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) * The BUILD_BUG_ON check must not involve any function calls, hence the * checks are done in macros here. */ -#define kfree_rcu(ptr, rhf) \ +#define kfree_rcu(ptr, rhf...) kvfree_rcu(ptr, ## rhf) + +/** + * kvfree_rcu() - kvfree an object after a grace period. + * + * This macro consists of one or two arguments and it is + * based on whether an object is head-less or not. If it + * has a head then a semantic stays the same as it used + * to be before: + * + * kvfree_rcu(ptr, rhf); + * + * where @ptr is a pointer to kvfree(), @rhf is the name + * of the rcu_head structure within the type of @ptr. + * + * When it comes to head-less variant, only one argument + * is passed and that is just a pointer which has to be + * freed after a grace period. Therefore the semantic is + * + * kvfree_rcu(ptr); + * + * where @ptr is the pointer to be freed by kvfree(). + * + * Please note, head-less way of freeing is permitted to + * use from a context that has to follow might_sleep() + * annotation. Otherwise, please switch and embed the + * rcu_head structure within the type of @ptr. + */ +#define kvfree_rcu(...) KVFREE_GET_MACRO(__VA_ARGS__, \ + kvfree_rcu_arg_2, kvfree_rcu_arg_1)(__VA_ARGS__) + +#define KVFREE_GET_MACRO(_1, _2, NAME, ...) NAME +#define kvfree_rcu_arg_2(ptr, rhf) \ do { \ typeof (ptr) ___p = (ptr); \ \ - if (___p) \ - __kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \ + if (___p) { \ + BUILD_BUG_ON(!__is_kvfree_rcu_offset(offsetof(typeof(*(ptr)), rhf))); \ + kvfree_call_rcu(&((___p)->rhf), (rcu_callback_t)(unsigned long) \ + (offsetof(typeof(*(ptr)), rhf))); \ + } \ +} while (0) + +#define kvfree_rcu_arg_1(ptr) \ +do { \ + typeof(ptr) ___p = (ptr); \ + \ + if (___p) \ + kvfree_call_rcu(NULL, (rcu_callback_t) (___p)); \ } while (0) /* @@ -873,7 +1029,7 @@ static inline void rcu_head_init(struct rcu_head *rhp) } /** - * rcu_head_after_call_rcu - Has this rcu_head been passed to call_rcu()? + * rcu_head_after_call_rcu() - Has this rcu_head been passed to call_rcu()? * @rhp: The rcu_head structure to test. * @f: The function passed to call_rcu() along with @rhp. * |