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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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C
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171/* SPDX-License-Identifier: GPL-2.0+ *//* * Sleepable Read-Copy Update mechanism for mutual exclusion, * tiny variant. * * Copyright (C) IBM Corporation, 2017 * * Author: Paul McKenney <paulmck@linux.ibm.com> */
#ifndef _LINUX_SRCU_TINY_H#define _LINUX_SRCU_TINY_H
#include <linux/irq_work_types.h>#include <linux/swait.h>
struct srcu_struct { short srcu_lock_nesting[2]; /* srcu_read_lock() nesting depth. */ u8 srcu_gp_running; /* GP workqueue running? */ u8 srcu_gp_waiting; /* GP waiting for readers? */ unsigned long srcu_idx; /* Current reader array element in bit 0x2. */ unsigned long srcu_idx_max; /* Furthest future srcu_idx request. */ struct swait_queue_head srcu_wq; /* Last srcu_read_unlock() wakes GP. */ struct rcu_head *srcu_cb_head; /* Pending callbacks: Head. */ struct rcu_head **srcu_cb_tail; /* Pending callbacks: Tail. */ struct work_struct srcu_work; /* For driving grace periods. */ struct irq_work srcu_irq_work; /* Defer schedule_work() to irq work. */#ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map;#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */};
void srcu_drive_gp(struct work_struct *wp);void srcu_tiny_irq_work(struct irq_work *irq_work);
#define __SRCU_STRUCT_INIT(name, __ignored, ___ignored, ____ignored) \{ \ .srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq), \ .srcu_cb_tail = &name.srcu_cb_head, \ .srcu_work = __WORK_INITIALIZER(name.srcu_work, srcu_drive_gp), \ .srcu_irq_work = { .func = srcu_tiny_irq_work }, \ __SRCU_DEP_MAP_INIT(name) \}
/* * This odd _STATIC_ arrangement is needed for API compatibility with * Tree SRCU, which needs some per-CPU data. */#define DEFINE_SRCU(name) \ struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name, name)#define DEFINE_STATIC_SRCU(name) \ static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name, name)#define DEFINE_SRCU_FAST(name) DEFINE_SRCU(name)#define DEFINE_STATIC_SRCU_FAST(name) \ static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name, name)#define DEFINE_SRCU_FAST_UPDOWN(name) DEFINE_SRCU(name)#define DEFINE_STATIC_SRCU_FAST_UPDOWN(name) \ static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name, name)
// Dummy structure for srcu_notifier_head.struct srcu_usage { };#define __SRCU_USAGE_INIT(name) { }#define __init_srcu_struct_fast __init_srcu_struct#define __init_srcu_struct_fast_updown __init_srcu_struct#ifndef CONFIG_DEBUG_LOCK_ALLOC#define init_srcu_struct_fast init_srcu_struct#define init_srcu_struct_fast_updown init_srcu_struct#endif // #ifndef CONFIG_DEBUG_LOCK_ALLOC
void synchronize_srcu(struct srcu_struct *ssp);
/* * Counts the new reader in the appropriate per-CPU element of the * srcu_struct. Can be invoked from irq/bh handlers, but the matching * __srcu_read_unlock() must be in the same handler instance. Returns an * index that must be passed to the matching srcu_read_unlock(). */static inline int __srcu_read_lock(struct srcu_struct *ssp) __acquires_shared(ssp){ int idx;
preempt_disable(); // Needed for PREEMPT_LAZY idx = ((READ_ONCE(ssp->srcu_idx) + 1) & 0x2) >> 1; WRITE_ONCE(ssp->srcu_lock_nesting[idx], READ_ONCE(ssp->srcu_lock_nesting[idx]) + 1); preempt_enable(); __acquire_shared(ssp); return idx;}
struct srcu_ctr;
static inline bool __srcu_ptr_to_ctr(struct srcu_struct *ssp, struct srcu_ctr __percpu *scpp){ return (int)(intptr_t)(struct srcu_ctr __force __kernel *)scpp;}
static inline struct srcu_ctr __percpu *__srcu_ctr_to_ptr(struct srcu_struct *ssp, int idx){ return (struct srcu_ctr __percpu *)(intptr_t)idx;}
static inline struct srcu_ctr __percpu *__srcu_read_lock_fast(struct srcu_struct *ssp) __acquires_shared(ssp){ return __srcu_ctr_to_ptr(ssp, __srcu_read_lock(ssp));}
static inline void __srcu_read_unlock_fast(struct srcu_struct *ssp, struct srcu_ctr __percpu *scp) __releases_shared(ssp){ __srcu_read_unlock(ssp, __srcu_ptr_to_ctr(ssp, scp));}
static inline struct srcu_ctr __percpu *__srcu_read_lock_fast_updown(struct srcu_struct *ssp) __acquires_shared(ssp){ return __srcu_ctr_to_ptr(ssp, __srcu_read_lock(ssp));}
static inlinevoid __srcu_read_unlock_fast_updown(struct srcu_struct *ssp, struct srcu_ctr __percpu *scp) __releases_shared(ssp){ __srcu_read_unlock(ssp, __srcu_ptr_to_ctr(ssp, scp));}
static inline void synchronize_srcu_expedited(struct srcu_struct *ssp){ synchronize_srcu(ssp);}
static inline void srcu_barrier(struct srcu_struct *ssp){ synchronize_srcu(ssp);}
static inline void srcu_expedite_current(struct srcu_struct *ssp) { }#define srcu_check_read_flavor(ssp, read_flavor) do { } while (0)
/* Defined here to avoid size increase for non-torture kernels. */static inline void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf){ int idx;
idx = ((data_race(READ_ONCE(ssp->srcu_idx)) + 1) & 0x2) >> 1; pr_alert("%s%s Tiny SRCU per-CPU(idx=%d): (%hd,%hd) gp: %lu->%lu\n", tt, tf, idx, data_race(READ_ONCE(ssp->srcu_lock_nesting[!idx])), data_race(READ_ONCE(ssp->srcu_lock_nesting[idx])), data_race(READ_ONCE(ssp->srcu_idx)), data_race(READ_ONCE(ssp->srcu_idx_max)));}
/** * srcu_readers_active - returns true if there are readers. and false otherwise. * @ssp: which srcu_struct to count active readers (holding srcu_read_lock). * * Note that this is not an atomic primitive, and can therefore suffer * severe errors when invoked on an active srcu_struct. That said, it * can be useful as an error check at cleanup time. */static inline bool srcu_readers_active(struct srcu_struct *ssp){ return READ_ONCE(ssp->srcu_lock_nesting[0]) || READ_ONCE(ssp->srcu_lock_nesting[1]);}
#endif