diff options
Diffstat (limited to 'include/linux/srcu.h')
| -rw-r--r-- | include/linux/srcu.h | 282 |
1 files changed, 198 insertions, 84 deletions
diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 900b0d5c05f5..81b1938512d5 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -21,12 +21,16 @@ #include <linux/workqueue.h> #include <linux/rcu_segcblist.h> -struct srcu_struct; +context_lock_struct(srcu_struct, __reentrant_ctx_lock); #ifdef CONFIG_DEBUG_LOCK_ALLOC -int __init_srcu_struct(struct srcu_struct *ssp, const char *name, - struct lock_class_key *key); +int __init_srcu_struct(struct srcu_struct *ssp, const char *name, struct lock_class_key *key); +#ifndef CONFIG_TINY_SRCU +int __init_srcu_struct_fast(struct srcu_struct *ssp, const char *name, struct lock_class_key *key); +int __init_srcu_struct_fast_updown(struct srcu_struct *ssp, const char *name, + struct lock_class_key *key); +#endif // #ifndef CONFIG_TINY_SRCU #define init_srcu_struct(ssp) \ ({ \ @@ -35,25 +39,45 @@ int __init_srcu_struct(struct srcu_struct *ssp, const char *name, __init_srcu_struct((ssp), #ssp, &__srcu_key); \ }) +#define init_srcu_struct_fast(ssp) \ +({ \ + static struct lock_class_key __srcu_key; \ + \ + __init_srcu_struct_fast((ssp), #ssp, &__srcu_key); \ +}) + +#define init_srcu_struct_fast_updown(ssp) \ +({ \ + static struct lock_class_key __srcu_key; \ + \ + __init_srcu_struct_fast_updown((ssp), #ssp, &__srcu_key); \ +}) + #define __SRCU_DEP_MAP_INIT(srcu_name) .dep_map = { .name = #srcu_name }, #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ int init_srcu_struct(struct srcu_struct *ssp); +#ifndef CONFIG_TINY_SRCU +int init_srcu_struct_fast(struct srcu_struct *ssp); +int init_srcu_struct_fast_updown(struct srcu_struct *ssp); +#endif // #ifndef CONFIG_TINY_SRCU #define __SRCU_DEP_MAP_INIT(srcu_name) #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ /* Values for SRCU Tree srcu_data ->srcu_reader_flavor, but also used by rcutorture. */ -#define SRCU_READ_FLAVOR_NORMAL 0x1 // srcu_read_lock(). -#define SRCU_READ_FLAVOR_NMI 0x2 // srcu_read_lock_nmisafe(). -#define SRCU_READ_FLAVOR_LITE 0x4 // srcu_read_lock_lite(). -#define SRCU_READ_FLAVOR_FAST 0x8 // srcu_read_lock_fast(). -#define SRCU_READ_FLAVOR_ALL (SRCU_READ_FLAVOR_NORMAL | SRCU_READ_FLAVOR_NMI | \ - SRCU_READ_FLAVOR_LITE | SRCU_READ_FLAVOR_FAST) // All of the above. -#define SRCU_READ_FLAVOR_SLOWGP (SRCU_READ_FLAVOR_LITE | SRCU_READ_FLAVOR_FAST) +#define SRCU_READ_FLAVOR_NORMAL 0x1 // srcu_read_lock(). +#define SRCU_READ_FLAVOR_NMI 0x2 // srcu_read_lock_nmisafe(). +// 0x4 // SRCU-lite is no longer with us. +#define SRCU_READ_FLAVOR_FAST 0x4 // srcu_read_lock_fast(), also NMI-safe. +#define SRCU_READ_FLAVOR_FAST_UPDOWN 0x8 // srcu_read_lock_fast_updown(). +#define SRCU_READ_FLAVOR_ALL (SRCU_READ_FLAVOR_NORMAL | SRCU_READ_FLAVOR_NMI | \ + SRCU_READ_FLAVOR_FAST | SRCU_READ_FLAVOR_FAST_UPDOWN) + // All of the above. +#define SRCU_READ_FLAVOR_SLOWGP (SRCU_READ_FLAVOR_FAST | SRCU_READ_FLAVOR_FAST_UPDOWN) // Flavors requiring synchronize_rcu() // instead of smp_mb(). -void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases(ssp); +void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases_shared(ssp); #ifdef CONFIG_TINY_SRCU #include <linux/srcutiny.h> @@ -107,14 +131,16 @@ static inline bool same_state_synchronize_srcu(unsigned long oldstate1, unsigned } #ifdef CONFIG_NEED_SRCU_NMI_SAFE -int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp); -void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) __releases(ssp); +int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires_shared(ssp); +void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) __releases_shared(ssp); #else static inline int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) + __acquires_shared(ssp) { return __srcu_read_lock(ssp); } static inline void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) + __releases_shared(ssp) { __srcu_read_unlock(ssp, idx); } @@ -186,6 +212,14 @@ static inline int srcu_read_lock_held(const struct srcu_struct *ssp) #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +/* + * No-op helper to denote that ssp must be held. Because SRCU-protected pointers + * should still be marked with __rcu_guarded, and we do not want to mark them + * with __guarded_by(ssp) as it would complicate annotations for writers, we + * choose the following strategy: srcu_dereference_check() calls this helper + * that checks that the passed ssp is held, and then fake-acquires 'RCU'. + */ +static inline void __srcu_read_lock_must_hold(const struct srcu_struct *ssp) __must_hold_shared(ssp) { } /** * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing @@ -199,9 +233,15 @@ static inline int srcu_read_lock_held(const struct srcu_struct *ssp) * to 1. The @c argument will normally be a logical expression containing * lockdep_is_held() calls. */ -#define srcu_dereference_check(p, ssp, c) \ - __rcu_dereference_check((p), __UNIQUE_ID(rcu), \ - (c) || srcu_read_lock_held(ssp), __rcu) +#define srcu_dereference_check(p, ssp, c) \ +({ \ + __srcu_read_lock_must_hold(ssp); \ + __acquire_shared_ctx_lock(RCU); \ + __auto_type __v = __rcu_dereference_check((p), __UNIQUE_ID(rcu), \ + (c) || srcu_read_lock_held(ssp), __rcu); \ + __release_shared_ctx_lock(RCU); \ + __v; \ +}) /** * srcu_dereference - fetch SRCU-protected pointer for later dereferencing @@ -244,7 +284,8 @@ static inline int srcu_read_lock_held(const struct srcu_struct *ssp) * invoke srcu_read_unlock() from one task and the matching srcu_read_lock() * from another. */ -static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp) +static inline int srcu_read_lock(struct srcu_struct *ssp) + __acquires_shared(ssp) { int retval; @@ -259,71 +300,111 @@ static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp) * @ssp: srcu_struct in which to register the new reader. * * Enter an SRCU read-side critical section, but for a light-weight - * smp_mb()-free reader. See srcu_read_lock() for more information. - * - * If srcu_read_lock_fast() is ever used on an srcu_struct structure, - * then none of the other flavors may be used, whether before, during, - * or after. Note that grace-period auto-expediting is disabled for _fast - * srcu_struct structures because auto-expedited grace periods invoke - * synchronize_rcu_expedited(), IPIs and all. - * - * Note that srcu_read_lock_fast() can be invoked only from those contexts - * where RCU is watching, that is, from contexts where it would be legal - * to invoke rcu_read_lock(). Otherwise, lockdep will complain. + * smp_mb()-free reader. See srcu_read_lock() for more information. This + * function is NMI-safe, in a manner similar to srcu_read_lock_nmisafe(). + * + * For srcu_read_lock_fast() to be used on an srcu_struct structure, + * that structure must have been defined using either DEFINE_SRCU_FAST() + * or DEFINE_STATIC_SRCU_FAST() on the one hand or initialized with + * init_srcu_struct_fast() on the other. Such an srcu_struct structure + * cannot be passed to any non-fast variant of srcu_read_{,un}lock() or + * srcu_{down,up}_read(). In kernels built with CONFIG_PROVE_RCU=y, + * __srcu_check_read_flavor() will complain bitterly if you ignore this + * restriction. + * + * Grace-period auto-expediting is disabled for SRCU-fast srcu_struct + * structures because SRCU-fast expedited grace periods invoke + * synchronize_rcu_expedited(), IPIs and all. If you need expedited + * SRCU-fast grace periods, use synchronize_srcu_expedited(). + * + * The srcu_read_lock_fast() function can be invoked only from those + * contexts where RCU is watching, that is, from contexts where it would + * be legal to invoke rcu_read_lock(). Otherwise, lockdep will complain. */ -static inline struct srcu_ctr __percpu *srcu_read_lock_fast(struct srcu_struct *ssp) __acquires(ssp) +static inline struct srcu_ctr __percpu *srcu_read_lock_fast(struct srcu_struct *ssp) __acquires_shared(ssp) + __acquires_shared(ssp) { struct srcu_ctr __percpu *retval; - srcu_check_read_flavor_force(ssp, SRCU_READ_FLAVOR_FAST); + RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_fast()."); + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST); retval = __srcu_read_lock_fast(ssp); rcu_try_lock_acquire(&ssp->dep_map); return retval; } /** - * srcu_down_read_fast - register a new reader for an SRCU-protected structure. + * srcu_read_lock_fast_updown - register a new reader for an SRCU-fast-updown structure. * @ssp: srcu_struct in which to register the new reader. * - * Enter a semaphore-like SRCU read-side critical section, but for - * a light-weight smp_mb()-free reader. See srcu_read_lock_fast() and - * srcu_down_read() for more information. - * - * The same srcu_struct may be used concurrently by srcu_down_read_fast() - * and srcu_read_lock_fast(). + * Enter an SRCU read-side critical section, but for a light-weight + * smp_mb()-free reader. See srcu_read_lock() for more information. + * This function is compatible with srcu_down_read_fast(), but is not + * NMI-safe. + * + * For srcu_read_lock_fast_updown() to be used on an srcu_struct + * structure, that structure must have been defined using either + * DEFINE_SRCU_FAST_UPDOWN() or DEFINE_STATIC_SRCU_FAST_UPDOWN() on the one + * hand or initialized with init_srcu_struct_fast_updown() on the other. + * Such an srcu_struct structure cannot be passed to any non-fast-updown + * variant of srcu_read_{,un}lock() or srcu_{down,up}_read(). In kernels + * built with CONFIG_PROVE_RCU=y, __srcu_check_read_flavor() will complain + * bitterly if you ignore this * restriction. + * + * Grace-period auto-expediting is disabled for SRCU-fast-updown + * srcu_struct structures because SRCU-fast-updown expedited grace periods + * invoke synchronize_rcu_expedited(), IPIs and all. If you need expedited + * SRCU-fast-updown grace periods, use synchronize_srcu_expedited(). + * + * The srcu_read_lock_fast_updown() function can be invoked only from + * those contexts where RCU is watching, that is, from contexts where + * it would be legal to invoke rcu_read_lock(). Otherwise, lockdep will + * complain. */ -static inline struct srcu_ctr __percpu *srcu_down_read_fast(struct srcu_struct *ssp) __acquires(ssp) +static inline struct srcu_ctr __percpu *srcu_read_lock_fast_updown(struct srcu_struct *ssp) + __acquires_shared(ssp) { - WARN_ON_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && in_nmi()); - srcu_check_read_flavor_force(ssp, SRCU_READ_FLAVOR_FAST); - return __srcu_read_lock_fast(ssp); + struct srcu_ctr __percpu *retval; + + RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_fast_updown()."); + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST_UPDOWN); + retval = __srcu_read_lock_fast_updown(ssp); + rcu_try_lock_acquire(&ssp->dep_map); + return retval; +} + +/* + * Used by tracing, cannot be traced and cannot call lockdep. + * See srcu_read_lock_fast() for more information. + */ +static inline struct srcu_ctr __percpu *srcu_read_lock_fast_notrace(struct srcu_struct *ssp) + __acquires_shared(ssp) +{ + struct srcu_ctr __percpu *retval; + + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST); + retval = __srcu_read_lock_fast(ssp); + return retval; } /** - * srcu_read_lock_lite - register a new reader for an SRCU-protected structure. + * srcu_down_read_fast - register a new reader for an SRCU-protected structure. * @ssp: srcu_struct in which to register the new reader. * - * Enter an SRCU read-side critical section, but for a light-weight - * smp_mb()-free reader. See srcu_read_lock() for more information. - * - * If srcu_read_lock_lite() is ever used on an srcu_struct structure, - * then none of the other flavors may be used, whether before, during, - * or after. Note that grace-period auto-expediting is disabled for _lite - * srcu_struct structures because auto-expedited grace periods invoke - * synchronize_rcu_expedited(), IPIs and all. + * Enter a semaphore-like SRCU read-side critical section, but for + * a light-weight smp_mb()-free reader. See srcu_read_lock_fast() and + * srcu_down_read() for more information. * - * Note that srcu_read_lock_lite() can be invoked only from those contexts - * where RCU is watching, that is, from contexts where it would be legal - * to invoke rcu_read_lock(). Otherwise, lockdep will complain. + * The same srcu_struct may be used concurrently by srcu_down_read_fast() + * and srcu_read_lock_fast(). However, the same definition/initialization + * requirements called out for srcu_read_lock_safe() apply. */ -static inline int srcu_read_lock_lite(struct srcu_struct *ssp) __acquires(ssp) +static inline struct srcu_ctr __percpu *srcu_down_read_fast(struct srcu_struct *ssp) __acquires_shared(ssp) { - int retval; - - srcu_check_read_flavor_force(ssp, SRCU_READ_FLAVOR_LITE); - retval = __srcu_read_lock_lite(ssp); - rcu_try_lock_acquire(&ssp->dep_map); - return retval; + WARN_ON_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && in_nmi()); + RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_down_read_fast()."); + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST_UPDOWN); + return __srcu_read_lock_fast_updown(ssp); } /** @@ -337,7 +418,8 @@ static inline int srcu_read_lock_lite(struct srcu_struct *ssp) __acquires(ssp) * then none of the other flavors may be used, whether before, during, * or after. */ -static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp) +static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) + __acquires_shared(ssp) { int retval; @@ -349,7 +431,8 @@ static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp /* Used by tracing, cannot be traced and cannot invoke lockdep. */ static inline notrace int -srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp) +srcu_read_lock_notrace(struct srcu_struct *ssp) + __acquires_shared(ssp) { int retval; @@ -380,7 +463,8 @@ srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp) * which calls to down_read() may be nested. The same srcu_struct may be * used concurrently by srcu_down_read() and srcu_read_lock(). */ -static inline int srcu_down_read(struct srcu_struct *ssp) __acquires(ssp) +static inline int srcu_down_read(struct srcu_struct *ssp) + __acquires_shared(ssp) { WARN_ON_ONCE(in_nmi()); srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL); @@ -395,7 +479,7 @@ static inline int srcu_down_read(struct srcu_struct *ssp) __acquires(ssp) * Exit an SRCU read-side critical section. */ static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx) - __releases(ssp) + __releases_shared(ssp) { WARN_ON_ONCE(idx & ~0x1); srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL); @@ -411,43 +495,57 @@ static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx) * Exit a light-weight SRCU read-side critical section. */ static inline void srcu_read_unlock_fast(struct srcu_struct *ssp, struct srcu_ctr __percpu *scp) - __releases(ssp) + __releases_shared(ssp) { srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST); srcu_lock_release(&ssp->dep_map); __srcu_read_unlock_fast(ssp, scp); + RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_unlock_fast()."); } /** - * srcu_up_read_fast - unregister a old reader from an SRCU-protected structure. + * srcu_read_unlock_fast_updown - unregister a old reader from an SRCU-fast-updown structure. * @ssp: srcu_struct in which to unregister the old reader. - * @scp: return value from corresponding srcu_read_lock_fast(). + * @scp: return value from corresponding srcu_read_lock_fast_updown(). * - * Exit an SRCU read-side critical section, but not necessarily from - * the same context as the maching srcu_down_read_fast(). + * Exit an SRCU-fast-updown read-side critical section. */ -static inline void srcu_up_read_fast(struct srcu_struct *ssp, struct srcu_ctr __percpu *scp) - __releases(ssp) +static inline void +srcu_read_unlock_fast_updown(struct srcu_struct *ssp, struct srcu_ctr __percpu *scp) __releases_shared(ssp) +{ + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST_UPDOWN); + srcu_lock_release(&ssp->dep_map); + __srcu_read_unlock_fast_updown(ssp, scp); + RCU_LOCKDEP_WARN(!rcu_is_watching(), + "RCU must be watching srcu_read_unlock_fast_updown()."); +} + +/* + * Used by tracing, cannot be traced and cannot call lockdep. + * See srcu_read_unlock_fast() for more information. + */ +static inline void srcu_read_unlock_fast_notrace(struct srcu_struct *ssp, + struct srcu_ctr __percpu *scp) __releases_shared(ssp) { - WARN_ON_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && in_nmi()); srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST); __srcu_read_unlock_fast(ssp, scp); } /** - * srcu_read_unlock_lite - unregister a old reader from an SRCU-protected structure. + * srcu_up_read_fast - unregister a old reader from an SRCU-protected structure. * @ssp: srcu_struct in which to unregister the old reader. - * @idx: return value from corresponding srcu_read_lock_lite(). + * @scp: return value from corresponding srcu_read_lock_fast(). * - * Exit a light-weight SRCU read-side critical section. + * Exit an SRCU read-side critical section, but not necessarily from + * the same context as the maching srcu_down_read_fast(). */ -static inline void srcu_read_unlock_lite(struct srcu_struct *ssp, int idx) - __releases(ssp) +static inline void srcu_up_read_fast(struct srcu_struct *ssp, struct srcu_ctr __percpu *scp) + __releases_shared(ssp) { - WARN_ON_ONCE(idx & ~0x1); - srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_LITE); - srcu_lock_release(&ssp->dep_map); - __srcu_read_unlock_lite(ssp, idx); + WARN_ON_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && in_nmi()); + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST_UPDOWN); + __srcu_read_unlock_fast_updown(ssp, scp); + RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_up_read_fast_updown()."); } /** @@ -458,7 +556,7 @@ static inline void srcu_read_unlock_lite(struct srcu_struct *ssp, int idx) * Exit an SRCU read-side critical section, but in an NMI-safe manner. */ static inline void srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) - __releases(ssp) + __releases_shared(ssp) { WARN_ON_ONCE(idx & ~0x1); srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NMI); @@ -468,7 +566,7 @@ static inline void srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) /* Used by tracing, cannot be traced and cannot call lockdep. */ static inline notrace void -srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp) +srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases_shared(ssp) { srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL); __srcu_read_unlock(ssp, idx); @@ -483,7 +581,7 @@ srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp) * the same context as the maching srcu_down_read(). */ static inline void srcu_up_read(struct srcu_struct *ssp, int idx) - __releases(ssp) + __releases_shared(ssp) { WARN_ON_ONCE(idx & ~0x1); WARN_ON_ONCE(in_nmi()); @@ -523,5 +621,21 @@ DEFINE_LOCK_GUARD_1(srcu, struct srcu_struct, _T->idx = srcu_read_lock(_T->lock), srcu_read_unlock(_T->lock, _T->idx), int idx) +DECLARE_LOCK_GUARD_1_ATTRS(srcu, __acquires_shared(_T), __releases_shared(*(struct srcu_struct **)_T)) +#define class_srcu_constructor(_T) WITH_LOCK_GUARD_1_ATTRS(srcu, _T) + +DEFINE_LOCK_GUARD_1(srcu_fast, struct srcu_struct, + _T->scp = srcu_read_lock_fast(_T->lock), + srcu_read_unlock_fast(_T->lock, _T->scp), + struct srcu_ctr __percpu *scp) +DECLARE_LOCK_GUARD_1_ATTRS(srcu_fast, __acquires_shared(_T), __releases_shared(*(struct srcu_struct **)_T)) +#define class_srcu_fast_constructor(_T) WITH_LOCK_GUARD_1_ATTRS(srcu_fast, _T) + +DEFINE_LOCK_GUARD_1(srcu_fast_notrace, struct srcu_struct, + _T->scp = srcu_read_lock_fast_notrace(_T->lock), + srcu_read_unlock_fast_notrace(_T->lock, _T->scp), + struct srcu_ctr __percpu *scp) +DECLARE_LOCK_GUARD_1_ATTRS(srcu_fast_notrace, __acquires_shared(_T), __releases_shared(*(struct srcu_struct **)_T)) +#define class_srcu_fast_notrace_constructor(_T) WITH_LOCK_GUARD_1_ATTRS(srcu_fast_notrace, _T) #endif |