| /* 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/swait.h> |
| |
| struct srcu_struct { |
| short srcu_lock_nesting[2]; /* srcu_read_lock() nesting depth. */ |
| unsigned short srcu_idx; /* Current reader array element in bit 0x2. */ |
| unsigned short srcu_idx_max; /* Furthest future srcu_idx request. */ |
| u8 srcu_gp_running; /* GP workqueue running? */ |
| u8 srcu_gp_waiting; /* GP waiting for readers? */ |
| 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. */ |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| struct lockdep_map dep_map; |
| #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
| }; |
| |
| void srcu_drive_gp(struct work_struct *wp); |
| |
| #define __SRCU_STRUCT_INIT(name, __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_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) |
| #define DEFINE_STATIC_SRCU(name) \ |
| static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name) |
| |
| 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) |
| { |
| int idx; |
| |
| idx = ((READ_ONCE(ssp->srcu_idx) + 1) & 0x2) >> 1; |
| WRITE_ONCE(ssp->srcu_lock_nesting[idx], ssp->srcu_lock_nesting[idx] + 1); |
| return idx; |
| } |
| |
| 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); |
| } |
| |
| /* 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 = ((READ_ONCE(ssp->srcu_idx) + 1) & 0x2) >> 1; |
| pr_alert("%s%s Tiny SRCU per-CPU(idx=%d): (%hd,%hd)\n", |
| tt, tf, idx, |
| READ_ONCE(ssp->srcu_lock_nesting[!idx]), |
| READ_ONCE(ssp->srcu_lock_nesting[idx])); |
| } |
| |
| #endif |